Rodolfo Dirzo
Associate Dean for Integrative Initiatives in Environmental Justice, Bing Prof in Environmental Science, Professor of Earth System Science and Senior Fellow at the Woods Institute for the Environment
Biology
Web page: https://dirzolab.stanford.edu/
Bio
My scientific work examines the study of species interactions in tropical ecosystems from California, Latin America, and other tropical areas of the world. Recent research highlights the decline of animal life (“defaunation”), and how this affects ecosystem processes/services (e.g. disease regulation). I teach ecology, natural history, conservation biology, and biocultural diversity at undergraduate and graduate levels at Stanford, and conduct science education programs with underserved children in the Bay Area and our study sites. My lab includes undergrads, graduate students, postdocs, and visiting scholars from the US, and many other countries. I have co-authored the new Framework for K-12 Science Education.
Administrative Appointments
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Co-Director, INOGO Program of the Woods Institute for the Environment (2011 - Present)
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Associate Chair for Diversity and Inclusion, School of Earth, Energy and Environment (2020 - Present)
Honors & Awards
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Pew Scholar in Conservation, The Pew Charitable Trust (1992)
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Outstanding Service Award: Teaching, Organization for Tropical Studies (2002)
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Member, Mexican Academy of Sciences (2003)
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Outstanding Researcher, Biology, National University of Mexico (2003)
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Presidential Award in Ecology, Secretary of Environment, Mexico (2003)
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Foreign Associate, US National Academy of Science (2004)
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Foreign Member, American Academy of Arts and Sciences (2004)
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Member, California Academy of Sciences (2008)
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Medal of Honor (Science),, The State Congress, Morelos, Mexico (2015)
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Merit in Ecology (Research), The Ecological Society of Mexico (2015)
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Miriam Arnold Rollan Prize for Community Service, Stanford University (2016)
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Medal Alfonso L. Herrera: Distinguished Scientist, Universidad Autonoma de Puebla, Mexico (2017)
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Medal for Merit in Research and Education, International Association for Tropical Biology (ATBC) (2017)
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President Miguel Aleman Medal for outstanding work in ecology and environmental problems, Mexico City (2017)
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Medal Luis Cifuentes, Mexican Federation of Biologists, Area of Research Puerto Vallarta, Mexico (2020)
Boards, Advisory Committees, Professional Organizations
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Board Member, Turning Green (2021 - Present)
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Board Member, Stop Extinction (2020 - Present)
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Group member, Zoonotic Diseases Working Group of International Union of Biological Sciences (2020 - Present)
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Committee member, Stanford Biology Diversity Equity and Inclusion (2020 - Present)
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Committee member, Stanford Public Art Committee (2019 - Present)
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Board Member, Stanford Breadth Governance Board (2019 - Present)
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Board Member, Biological Sciences Curriculum Studies (2019 - Present)
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Advisory Board, Stanford Bing Over Seas Program (2013 - Present)
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Advisory Committee, Jasper Ridge Biological Preserve (2008 - Present)
Program Affiliations
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Center for Latin American Studies
Professional Education
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B.Sc., University of Morelos, Mexico, Biology (1972)
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M.Sc., University of Wales, Ecology (1977)
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Ph.D., University of Wales, Ecology (1980)
Community and International Work
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Plant-animal interactions, Mexico, Costa Rica, Amazonia
Topic
ecology and evolutionary biology
Partnering Organization(s)
National University of Mexico, Organization for Tropical Studies, Amazonian Institute of Research
Populations Served
USA and LAtin American Students and policy makers
Location
International
Ongoing Project
Yes
Opportunities for Student Involvement
Yes
Current Research and Scholarly Interests
My interests are centered on the study of species interactions, trying to understand how the ecology and evolution of plants is affected by other living organisms, particularly animals (herbivores, pollinators, seed dispersal agents, and seed predators) and pathogens. My work is focused on tropical forest ecosystems, particulalry in Latin America, particularly Mexico, Costa Rica and Amazonia, but I am also conducting similar studies in other ecosystems as well. More recently, I have been conducting research in East Africa (Kenya, Tanzania), looking at how anthropogenic impact affects ecological interactions between plants and animals.
In the field of conservation biology, I am interested in studying the consequences of anthropogenic impact on the disruption of ecological processes and ecosystem services, including the importance of species interactions in human disease regulation.
Finally, I have a major interest in environmental education and sharing of my experiences in ecology and conservation, with the general public and students of all levels.
Projects
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Effect of Herbivores on Plant Diversity, National University of Mexico (UNAM)
This project examines via experimental manipulations and observations, the impact of herbivores on plant community, structure and diversity.
Location
Mexico
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Effects of natural enemies (herbivorous animals and fungi) on the ecology of plants in tropical forest ecosystems, Stanford University, in collaboration with UNAM (Mexico), and other Brazilian institutions
We seek to understand how the plants' natural enemies affect the ecology and evolutionary trajectories of plants in tropical ecosystems in Latin America.
Location
Mexico, Costa Rica, Panama, Brazil.
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Anthropogenic impact on species interactions in tropical and temperate ecosystems, Stanford University
This is a multi-faceted project aimed at understanding how drivers of global environmental change (deforestation, animal over-exploitation [defaunation], invasive species, and the interaction among drivers of global change affect the ecological interactions between species and how this, in turn, threatens ecosystem services.
Location
Mexico, Brazil, Kenya, the Channel Islands (Central Pacific)
Collaborators
- Hillary Young, Professor, University of California Santa Barbara
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Effects of biological enrichment on biodiversity and disease risk in oil palm plantations, Stanford University (Woods Institute)
We are experimentally testing the effects of diversification (plant species enrichment) on the control of disease and productivity of oil palms, as well as on zoonotic disease risks in humans, as part of a larger project (INOGO) that attempts to combine biodiversity conservation with human wellbeing.
Location
OSa Peninsula and Golfito Canton in Costa Rica
Collaborators
- Willliam Durham, Professor, Stanford University
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Effects of defamation on ecosystem processes and services
This research examines how the local loss of animal populations affects ecosystem processes generating a cascade of ecological consequences including degradation or loss of ecosystem services such as disease regulation
Location
Mexico, Kenya, Costa Rica
Collaborators
- Michael Scmidt, Senior Researcher, Mexico's NAtional Commission for Biodiversity
2024-25 Courses
- Conservation Biology: A Latin American Perspective
BIO 144, BIO 234, HUMBIO 112 (Spr) - Ecology and Natural History of Jasper Ridge Biological Preserve
BIO 105A (Win) - Ecology and Natural History of Jasper Ridge Biological Preserve
BIO 105B (Spr) - Ecology and Natural History of Jasper Ridge Biological Preserve
EARTHSYS 105A (Win) - Ecology and Natural History of Jasper Ridge Biological Preserve
EARTHSYS 105B (Spr) - Ornithology
BIO 121, BIO 221 (Spr) - Where the Wild Things Are: The Ecology and Ethics of Conserving Megafauna
BIO 185, DLCL 170, EALC 170, EARTHSYS 170, GLOBAL 170 (Win) -
Independent Studies (13)
- Curricular Practical Training
BIO 292 (Aut, Win, Spr) - Directed Individual Study in Earth Systems
EARTHSYS 297 (Aut, Win, Spr) - Directed Reading in Biology
BIO 198 (Aut, Win, Spr) - Directed Reading in Environment and Resources
ENVRES 398 (Aut, Win, Spr) - Directed Research
EARTHSYS 250 (Aut, Win, Spr) - Directed Research in Environment and Resources
ENVRES 399 (Aut, Win, Spr) - Graduate Research
BIO 300 (Aut, Win, Spr) - Graduate Research
ESS 400 (Aut, Win, Spr) - Honors Program in Earth Systems
EARTHSYS 199 (Aut, Win, Spr) - Out-of-Department Directed Reading
BIO 198X (Aut, Win, Spr) - Senior Honors Thesis
URBANST 199 (Aut, Win, Spr) - Teaching Practicum in Biology
BIO 290 (Aut, Win, Spr) - Undergraduate Research
BIO 199 (Aut, Win, Spr)
- Curricular Practical Training
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Prior Year Courses
2023-24 Courses
- Conservation Biology: A Latin American Perspective
BIO 144, BIO 234, HUMBIO 112 (Spr) - Ecology and Natural History of Jasper Ridge Biological Preserve
BIO 105A (Win) - Ecology and Natural History of Jasper Ridge Biological Preserve
BIO 105B (Spr) - Ecology and Natural History of Jasper Ridge Biological Preserve
EARTHSYS 105A (Win) - Ecology and Natural History of Jasper Ridge Biological Preserve
EARTHSYS 105B (Spr) - Ornithology
BIO 121, BIO 221 (Spr) - Sustainability and Civilization
BIO 35, HISTORY 35, POLISCI 35 (Win) - Where the Wild Things Are: The Ecology and Ethics of Conserving Megafauna
BIO 185, DLCL 170, EALC 170, EARTHSYS 170, GLOBAL 170 (Win)
2022-23 Courses
- Bio-Cultural Diversity and Community-Based Conservation in Oaxaca
OSPGEN 63 (Sum) - Conservation Biology: A Latin American Perspective
BIO 144, BIO 234, HUMBIO 112 (Spr) - Ecology and Natural History of Jasper Ridge Biological Preserve
BIO 105A (Win) - Ecology and Natural History of Jasper Ridge Biological Preserve
BIO 105B (Spr) - Ecology and Natural History of Jasper Ridge Biological Preserve
EARTHSYS 105A (Win) - Ecology and Natural History of Jasper Ridge Biological Preserve
EARTHSYS 105B (Spr) - Global Change in the Antropocene: An Iberoamerican Perspective
OSPMADRD 10 (Aut) - Sustainability and Civilization
BIO 35 (Win)
2021-22 Courses
- Conservation Biology: A Latin American Perspective
BIO 144, BIO 234, HUMBIO 112 (Spr) - Ecology and Natural History of Jasper Ridge Biological Preserve
BIO 105A (Win) - Ecology and Natural History of Jasper Ridge Biological Preserve
BIO 105B (Spr) - Ecology and Natural History of Jasper Ridge Biological Preserve
EARTHSYS 105A (Win) - Ecology and Natural History of Jasper Ridge Biological Preserve
EARTHSYS 105B (Spr) - Global Change in Chile
OSPSANTG 58 (Win) - Ornithology
BIO 121, BIO 221 (Spr) - Spanish in Science/Science in Spanish
BIO 208, EARTHSYS 207, LATINAM 207 (Spr) - Understanding Restoration Ecology from the Lens of Restorative Justice
BIO 106 (Spr)
- Conservation Biology: A Latin American Perspective
Stanford Advisees
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Alexander Basaraba, Adam Spitzig -
Doctoral Dissertation Reader (AC)
Oliver Nguyen -
Doctoral Dissertation Advisor (AC)
Rodrigo Bello Carvalho, TJ Francisco, Luísa Genes, Tenzin Norzin, Chinmay Sonawane -
Master's Program Advisor
Alan Cuevas, Samantha Faul, Matt Murphy, Valeria Paez Pulido, Alexandria Quan, Varun Shirhatti -
Doctoral Dissertation Co-Advisor (AC)
Sergio Sanchez -
Undergraduate Major Advisor
Kimberly Cheung -
Doctoral (Program)
Luísa Genes, Audrey Hsi
Graduate and Fellowship Programs
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Biology (School of Humanities and Sciences) (Phd Program)
All Publications
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Responses of oak seedlings to increased herbivory and drought: a possible trade-off?
Annals of botany
2024
Abstract
Anthropogenic disturbances are causing a co-occurring increase in biotic (ungulate herbivory) and abiotic (drought) stressors, threatening plant reproduction in oak-dominated ecosystems. However, we wonder whether herbivory could compensate for the adverse impact of drought by reducing evapotranspiration. Thus, we investigate the isolated and joint effects of herbivory and drought on oak seedlings of two contrasting Mediterranean species that differ in leaf habit and drought resistance.California oak seedlings from the evergreen, and more drought-resistant, Quercus agrifolia and the deciduous Q. lobata (n=387) were assigned to a fully crossed factorial design with herbivory and drought as stress factors. Seedlings were assigned in a greenhouse to 3-4 clipping levels simulating herbivory and 3-4 watering levels, depending on the species. We measured survival, growth, and leaf attributes (chlorophyll, secondary metabolites, leaf area and weight) once a month (May-Sep) and harvested above- and below-ground biomass at the end of the growing season.For both oak species, simulated herbivory enhanced seedling survival during severe drought or delayed its adverse effects, probably due to reduced transpiration resulting from herbivory-induced leaf area reduction and compensatory root growth. Seedlings from the deciduous, and less drought-resistant species, benefitted from herbivory at lower levels of water stress, suggesting different response across species. We also found complex interactions between herbivory and drought on their impact on leaf attributes. In contrast to chlorophyll content which was not affected by herbivory, anthocyanins increased with herbivory - although water stress reduced differences in anthocyanins due to herbivory.Herbivory seems to facilitate Mediterranean oak seedlings to withstand summer drought, potentially alleviating a key bottleneck in the oak recruitment process. Our study highlights the need to consider ontogenetic stages and species-specific traits in understanding complex relationships between herbivory and drought stressors for the persistence and restoration of multi-species oak savannas.
View details for DOI 10.1093/aob/mcae178
View details for PubMedID 39383257
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Scientists' warning: six key points where biodiversity can improve climate change mitigation
BIOSCIENCE
2024
View details for DOI 10.1093/biosci/biae035
View details for Web of Science ID 001229399300001
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Vulnerability of seedlings to herbivore and pathogen attack: the importance of plant vigor and plant nutritional quality in <i>Hymenaea courbaril</i>
ARTHROPOD-PLANT INTERACTIONS
2024
View details for DOI 10.1007/s11829-024-10067-4
View details for Web of Science ID 001217500100001
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Evaluating stealth health and environmental conservation education among diverse youth in California: moving towards narrowing disparities
JOURNAL OF OUTDOOR AND ENVIRONMENTAL EDUCATION
2024
View details for DOI 10.1007/s42322-024-00169-1
View details for Web of Science ID 001205183500001
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Mycorrhizal type and tree diversity affect foliar elemental pools and stoichiometry.
The New phytologist
2024
Abstract
Species-specific differences in nutrient acquisition strategies allow for complementary use of resources among plants in mixtures, which may be further shaped by mycorrhizal associations. However, empirical evidence of this potential role of mycorrhizae is scarce, particularly for tree communities. We investigated the impact of tree species richness and mycorrhizal types, arbuscular mycorrhizal fungi (AM) and ectomycorrhizal fungi (EM), on above- and belowground carbon (C), nitrogen (N), and phosphorus (P) dynamics. Soil and soil microbial biomass elemental dynamics showed weak responses to tree species richness and none to mycorrhizal type. However, foliar elemental concentrations, stoichiometry, and pools were significantly affected by both treatments. Tree species richness increased foliar C and P pools but not N pools. Additive partitioning analyses showed that net biodiversity effects of foliar C, N, P pools in EM tree communities were driven by selection effects, but in mixtures of both mycorrhizal types by complementarity effects. Furthermore, increased tree species richness reduced soil nitrate availability, over 2 yr. Our results indicate that positive effects of tree diversity on aboveground nutrient storage are mediated by complementary mycorrhizal strategies and highlight the importance of using mixtures composed of tree species with different types of mycorrhizae to achieve more multifunctional afforestation.
View details for DOI 10.1111/nph.19732
View details for PubMedID 38594212
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Habitat protection and removal of encroaching shrubs support the recovery of biodiversity and ecosystem functioning
CONSERVATION SCIENCE AND PRACTICE
2024
View details for DOI 10.1111/csp2.13111
View details for Web of Science ID 001186877400001
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Underlying and proximate drivers of biodiversity changes in Mesoamerican biosphere reserves.
Proceedings of the National Academy of Sciences of the United States of America
2024; 121 (6): e2305944121
Abstract
Protected areas are of paramount relevance to conserving wildlife and ecosystem contributions to people. Yet, their conservation success is increasingly threatened by human activities including habitat loss, climate change, pollution, and species overexploitation. Thus, understanding the underlying and proximate drivers of anthropogenic threats is urgently needed to improve protected areas' effectiveness, especially in the biodiversity-rich tropics. We addressed this issue by analyzing expert-provided data on long-term biodiversity change (last three decades) over 14 biosphere reserves from the Mesoamerican Biodiversity Hotspot. Using multivariate analyses and structural equation modeling, we tested the influence of major socioeconomic drivers (demographic, economic, and political factors), spatial indicators of human activities (agriculture expansion and road extension), and forest landscape modifications (forest loss and isolation) as drivers of biodiversity change. We uncovered a significant proliferation of disturbance-tolerant guilds and the loss or decline of disturbance-sensitive guilds within reserves causing a "winner and loser" species replacement over time. Guild change was directly related to forest spatial changes promoted by the expansion of agriculture and roads within reserves. High human population density and low nonfarming occupation were identified as the main underlying drivers of biodiversity change. Our findings suggest that to mitigate anthropogenic threats to biodiversity within biosphere reserves, fostering human population well-being via sustainable, nonfarming livelihood opportunities around reserves is imperative.
View details for DOI 10.1073/pnas.2305944121
View details for PubMedID 38252845
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Lasting effects of avian-frugivore interactions on seed dispersal and seedling establishment
JOURNAL OF ECOLOGY
2024
View details for DOI 10.1111/1365-2745.14260
View details for Web of Science ID 001146346800001
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Association between anthropization and rodent reservoirs of zoonotic pathogens in Northwestern Mexico.
PloS one
2024; 19 (2): e0298976
Abstract
The world is facing a major pulse of ecological and social changes that may favor the risk of zoonotic outbreaks. Such risk facilitation may occur through the modification of the host's community diversity and structure, leading to an increase in pathogen reservoirs and the contact rate between these reservoirs and humans. Here, we examined whether anthropization alters the relative abundance and richness of zoonotic reservoir and non-reservoir rodents in three Socio-Ecological Systems. We hypothesized that anthropization increases the relative abundance and richness of rodent reservoirs while decreasing non-reservoir species. We first developed an Anthropization index based on 15 quantitative socio-ecological variables classified into five groups: 1) Vegetation type, 2) Urbanization degree, 3) Water quality, 4) Potential contaminant sources, and 5) Others. We then monitored rodent communities in three regions of Northwestern Mexico (Baja California, Chihuahua, and Sonora). A total of 683 rodents of 14 genera and 27 species were captured, nine of which have been identified as reservoirs of zoonotic pathogens (359 individuals, 53%). In all regions, we found that as anthropization increased, the relative abundance of reservoir rodents increased; in contrast, the relative abundance of non-reservoir rodents decreased. In Sonora, reservoir richness increased with increasing anthropization, while in Baja California and Chihuahua non-reservoir richness decreased as anthropization increased. We also found a significant positive relationship between the anthropization degree and the abundance of house mice (Mus musculus) and deer mice (Peromyscus maniculatus), the most abundant reservoir species in the study. These findings support the hypothesis that reservoir species of zoonotic pathogens increase their abundance in disturbed environments, which may increase the risk of pathogen exposure to humans, while anthropization creates an environmental filtering that promotes the local extinction of non-reservoir species.
View details for DOI 10.1371/journal.pone.0298976
View details for PubMedID 38386681
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Mixed population trends inside a California protected area: Evidence from long-term community science monitoring
IBIS
2023
View details for DOI 10.1111/ibi.13280
View details for Web of Science ID 001099825500001
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Explaining variation in plant-herbivore associational effects in a tree biodiversity experiment
JOURNAL OF ECOLOGY
2023
View details for DOI 10.1111/1365-2745.14212
View details for Web of Science ID 001086450800001
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Female philopatry and unsuccessful male dispersal of a top predator in a human-modified landscape revealed by relatedness analysis
EUROPEAN JOURNAL OF WILDLIFE RESEARCH
2023; 69 (5)
View details for DOI 10.1007/s10344-023-01726-7
View details for Web of Science ID 001066500100001
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Tropical Dry Forest Restoration in an Era of Global Change: Ecological and Social Dimensions
SUSTAINABILITY
2023; 15 (4)
View details for DOI 10.3390/su15043052
View details for Web of Science ID 000941231100001
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The Herbaceous Understory Plant Community in the Context of the Overstory: An Overlooked Component of Tropical Diversity
DIVERSITY-BASEL
2022; 14 (10)
View details for DOI 10.3390/d14100800
View details for Web of Science ID 000872770400001
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Modeling multiple ecosystem services and beneficiaries of riparian reforestation in Costa Rica
ECOSYSTEM SERVICES
2022; 57
View details for DOI 10.1016/j.ecoser.2022.101470
View details for Web of Science ID 000862222900005
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Circling the drain: the extinction crisis and the future of humanity.
Philosophical transactions of the Royal Society of London. Series B, Biological sciences
2022; 377 (1857): 20210378
Abstract
Humanity has triggered the sixth mass extinction episode since the beginning of the Phanerozoic. The complexity of this extinction crisis is centred on the intersection of two complex adaptive systems: human culture and ecosystem functioning, although the significance of this intersection is not properly appreciated. Human beings are part of biodiversity and elements in a global ecosystem. Civilization, and perhaps even the fate of our species, is utterly dependent on that ecosystem's proper functioning, which society is increasingly degrading. The crisis seems rooted in three factors. First, relatively few people globally are aware of its existence. Second, most people who are, and even many scientists, assume incorrectly that the problem is primarily one of the disappearance of species, when it is the existential threat of myriad population extinctions. Third, while concerned scientists know there are many individual and collective steps that must be taken to slow population extinction rates, some are not willing to advocate the one fundamental, necessary, 'simple' cure, that is, reducing the scale of the human enterprise. We argue that compassionate shrinkage of the human population by further encouraging lower birth rates while reducing both inequity and aggregate wasteful consumption-that is, an end to growthmania-will be required. This article is part of the theme issue 'Ecological complexity and the biosphere: the next 30 years'.
View details for DOI 10.1098/rstb.2021.0378
View details for PubMedID 35757873
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Broad-scale climate variation drives the dynamics of animal populations: a global multi-taxa analysis.
Biological reviews of the Cambridge Philosophical Society
2022
Abstract
Climate is a major extrinsic factor affecting the population dynamics of many organisms. The Broad-Scale Climate Hypothesis (BSCH) was proposed by Elton to explain the large-scale synchronous population cycles of animals, but the extent of support and whether it differs among taxa and geographical regions is unclear. We reviewed publications examining the relationship between the population dynamics of multiple taxa worldwide and the two most commonly used broad-scale climate indices, El Nino-Southern Oscillation (ENSO) and North Atlantic Oscillation (NAO). Our review and synthesis (based on 561 species from 221 papers) reveals that population changes of mammals, birds and insects are strongly affected by major oceanic shifts or irregular oceanic changes, particularly in ENSO- and NAO-influenced regions (Pacific and Atlantic, respectively), providing clear evidence supporting Elton's BSCH. Mammal and insect populations tended to increase during positive ENSO phases. Bird populations tended to increase in positive NAO phases. Some species showed dual associations with both positive and negative phases of the same climate index (ENSO or NAO). These findings indicate that some taxa or regions are more or less vulnerable to climate fluctuations and that some geographical areas show multiple weather effects related to ENSO or NAO phases. Beyond confirming that animal populations are influenced by broad-scale climate variation, we document extensive patterns of variation among taxa and observe that the direct biotic and abiotic mechanisms for these broad-scale climate factors affecting animal populations are very poorly understood. A practical implication of our research is that changes in ENSO or NAO can be used as early signals for pest management and wildlife conservation. We advocate integrative studies at both broad and local scales to unravel the omnipresent effects of climate on animal populations to help address the challenge of conserving biodiversity in this era of accelerated climate change.
View details for DOI 10.1111/brv.12888
View details for PubMedID 35942895
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Frugivore Population Biomass, but Not Density, Affect Seed Dispersal Interactions in a Hyper-Diverse Frugivory Network
FRONTIERS IN ECOLOGY AND EVOLUTION
2022; 10
View details for DOI 10.3389/fevo.2022.794723
View details for Web of Science ID 000797479000001
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Predator-prey interactions of terrestrial invertebrates are determined by predator body size and species identity.
Ecology
1800: e3634
Abstract
Predator-prey interactions shape ecosystems and can help maintain biodiversity. However, for many of the earth's most biodiverse and abundant organisms, including terrestrial arthropods, these interactions are difficult or impossible to observe directly with traditional approaches. Based on previous theory, it is likely that predator-prey interactions for these organisms are shaped by a combination of predator traits, including body size and species-specific hunting strategies. In this study, we combined diet DNA metabarcoding data of 173 individual invertebrate predators from nine species (a total of 305 individual predator-prey interactions) with an extensive community body size dataset of a well-described invertebrate community to explore how predator traits and identity shape interactions. We found that 1) mean size of prey families in the field usually scaled with predator size, with species-specific variation to a general size scaling relationship (exceptions likely indicating scavenging or feeding on smaller life stages). We also found that 2) although predator hunting traits, including web and venom use, are thought to shape predator-prey interaction outcomes, predator identity more strongly influenced our indirect measure of the relative size of predators and prey (predator:prey size ratios) than either of these hunting traits. Our findings indicate that predator body size and species identity are important in shaping trophic interactions in invertebrate food webs and could help predict how anthropogenic biodiversity change will influence terrestrial invertebrates, the earth's most diverse animal taxonomic group.
View details for DOI 10.1002/ecy.3634
View details for PubMedID 35060625
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Restoration of plant-animal interactions in terrestrial ecosystems
BIOLOGICAL CONSERVATION
2022; 265
View details for DOI 10.1016/j.biocon.2021.109393
View details for Web of Science ID 000729020900004
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On the move: spatial ecology and habitat use of red fox in the Trans-Himalayan cold desert.
PeerJ
2022; 10: e13967
Abstract
Red fox (Vulpes vulpes) is the most widespread wild carnivore globally, occupying diverse habitats. The species is known for its adaptability to survive in dynamic anthropogenic landscapes. Despite being one of the most extensively studied carnivores, there is a dearth of information on red fox from the Trans-Himalayan region. We studied the home range sizes of red fox using the different estimation methods: minimum convex polygon (MCP), kernel density estimator (KDE), local convex hull (LoCoH) and Brownian-bridge movement model (BBMM). We analysed the daily movement and assessed the habitat selection with respect to topographic factors (ruggedness, elevation and slope), environmental factor (distance to water) and anthropogenic factors (distance to road and human settlements). We captured and GPS-collared six red fox individuals (three males and three females) from Chiktan and one female from Hemis National Park, Ladakh, India. The collars were programmed to record GPS fixes every 15-min. The average BBMM home range estimate (95% contour) was 22.40 ± 12.12 SD km2 (range 3.81-32.93 km2) and the average core area (50% contour) was 1.87 ± 0.86 SD km2 (range 0.55-2.69 km2). The estimated average daily movement of red fox was 17.76 ± 8.45 SD km/d (range 10.91-34.22 km/d). Red fox significantly selected lower elevations with less rugged terrain and were positively associated with water. This is the first study in the Trans-Himalayan landscape which aims to understand the daily movement of red fox at a fine temporal scale. Studying the movement and home range sizes helps understand the daily energetics and nutritional requirements of red fox. Movement information of a species is important for the prioritisation of areas for conservation and can aid in understanding ecosystem functioning and landscape management.
View details for DOI 10.7717/peerj.13967
View details for PubMedID 36128190
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Rapid morphological change in a small mammal species after habitat fragmentation over the past half-century
DIVERSITY AND DISTRIBUTIONS
2021
View details for DOI 10.1111/ddi.13437
View details for Web of Science ID 000714254800001
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A review of philopatry and dispersal in felids living in an anthropised worldPalavras-chave
MAMMAL REVIEW
2021
View details for DOI 10.1111/mam.12275
View details for Web of Science ID 000707672300001
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Differences in mutualistic or predatory interactions between tree and rodent species as revealed by using a double-duplex passive integrated transponder tagging technique
ACTA OECOLOGICA-INTERNATIONAL JOURNAL OF ECOLOGY
2021; 112
View details for DOI 10.1016/j.actao.2021.103747
View details for Web of Science ID 000691322300002
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Phenotypic plasticity in plant defense across life stages: Inducibility, transgenerational induction, and transgenerational priming in wild radish.
Proceedings of the National Academy of Sciences of the United States of America
2021; 118 (33)
Abstract
As they develop, many plants deploy shifts in antiherbivore defense allocation due to changing costs and benefits of their defensive traits. Plant defenses are known to be primed or directly induced by herbivore damage within generations and across generations by long-lasting epigenetic mechanisms. However, little is known about the differences between life stages of epigenetically inducible defensive traits across generations. To help fill this knowledge gap, we conducted a multigenerational experiment to determine whether defense induction in wild radish plants was reflected in chromatin modifications (DNA methylation); we then examined differences between seedlings and reproductive plants in current and transgenerational plasticity in chemical (glucosinolates) and physical (trichomes) defenses in this species. Herbivory triggered genome methylation both in targeted plants and their offspring. Within one generation, both defenses were highly inducible at the seedling stage, but only chemical defenses were inducible in reproductive plants. Across generations, herbivory experienced by mother plants caused strong direct induction of physical defenses in their progeny, with effects lasting from seedling to reproductive stages. For chemical defenses, however, this transgenerational induction was evident only in adults. Transgenerational priming was observed in physical and chemical defenses, particularly in adult plants. Our results show that transgenerational plasticity in plant defenses in response to herbivore offense differs for physical and chemical defense and changes across plant life stages.
View details for DOI 10.1073/pnas.2005865118
View details for PubMedID 34389664
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Effects of Domestic and Wild Ungulate Management on Young Oak Size and Architecture
SUSTAINABILITY
2021; 13 (14)
View details for DOI 10.3390/su13147930
View details for Web of Science ID 000677024000001
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Logging drives contrasting animal body-size effects on tropical forest mammal communities
FOREST ECOLOGY AND MANAGEMENT
2021; 481
View details for DOI 10.1016/j.foreco.2020.118700
View details for Web of Science ID 000607186400003
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Jose Mario Molina: Life and legacy of a man who helped to save Earth's ozone layer.
Proceedings of the National Academy of Sciences of the United States of America
2021; 118 (1)
View details for DOI 10.1073/pnas.2023954118
View details for PubMedID 33328336
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Successful neighbour: Interactions of the generalist carnivore red fox with dogs, wolves and humans for continued survival in dynamic anthropogenic landscapes
GLOBAL ECOLOGY AND CONSERVATION
2021; 25
View details for DOI 10.1016/j.gecco.2020.e01446
View details for Web of Science ID 000615947800009
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Human-mediated impacts on biodiversity and the consequences for zoonotic disease spillover.
Current biology : CB
2021; 31 (19): R1342-R1361
Abstract
Human-mediated changes to natural ecosystems have consequences for both ecosystem and human health. Historically, efforts to preserve or restore 'biodiversity' can seem to be in opposition to human interests. However, the integration of biodiversity conservation and public health has gained significant traction in recent years, and new efforts to identify solutions that benefit both environmental and human health are ongoing. At the forefront of these efforts is an attempt to clarify ways in which biodiversity conservation can help reduce the risk of zoonotic spillover of pathogens from wild animals, sparking epidemics and pandemics in humans and livestock. However, our understanding of the mechanisms by which biodiversity change influences the spillover process is incomplete, limiting the application of integrated strategies aimed at achieving positive outcomes for both conservation and disease management. Here, we review the literature, considering a broad scope of biodiversity dimensions, to identify cases where zoonotic pathogen spillover is mechanistically linked to changes in biodiversity. By reframing the discussion around biodiversity and disease using mechanistic evidence - while encompassing multiple aspects of biodiversity including functional diversity, landscape diversity, phenological diversity, and interaction diversity - we work toward general principles that can guide future research and more effectively integrate the related goals of biodiversity conservation and spillover prevention. We conclude by summarizing how these principles could be used to integrate the goal of spillover prevention into ongoing biodiversity conservation initiatives.
View details for DOI 10.1016/j.cub.2021.08.070
View details for PubMedID 34637744
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Transgenerational Plasticity in Flower Color Induced by Caterpillars.
Frontiers in plant science
2021; 12: 617815
Abstract
Variation in flower color due to transgenerational plasticity could stem directly from abiotic or biotic environmental conditions. Finding a link between biotic ecological interactions across generations and plasticity in flower color would indicate that transgenerational effects of ecological interactions, such as herbivory, might be involved in flower color evolution. We conducted controlled experiments across four generations of wild radish (Raphanus sativus, Brassicaceae) plants to explore whether flower color is influenced by herbivory, and to determine whether flower color is associated with transgenerational chromatin modifications. We found transgenerational effects of herbivory on flower color, partly related to chromatin modifications. Given the presence of herbivory in plant populations worldwide, our results are of broad significance and contribute to our understanding of flower color evolution.
View details for DOI 10.3389/fpls.2021.617815
View details for PubMedID 33790921
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TROPICAL RAINFOREST FRAGMENTATION AFFECTS PLANT SPECIES RICHNESS, COMPOSITION AND ABUNDANCE DEPENDING ON PLANT-SIZE CLASS AND LIFE HISTORY
BOTANICAL SCIENCES
2021; 99 (1): 92–103
View details for DOI 10.17129/botsci.2679
View details for Web of Science ID 000604984800008
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Incidence of Galls on Sympatric California Oaks: Ecological and Physiological Perspectives
DIVERSITY-BASEL
2021; 13 (1)
View details for DOI 10.3390/d13010020
View details for Web of Science ID 000610134000001
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Forest fragmentation and defaunation drive an unusual ecological cascade: Predation release, monkey population outburst and plant demographic collapse
BIOLOGICAL CONSERVATION
2020; 252
View details for DOI 10.1016/j.biocon.2020.108852
View details for Web of Science ID 000600455000008
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Matching species traits and microsites improves regeneration in mixed oak woodlands
APPLIED VEGETATION SCIENCE
2020
View details for DOI 10.1111/avsc.12536
View details for Web of Science ID 000581128200001
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Impacts of rodent eradication on seed predation and plant community biomass on a tropical atoll
BIOTROPICA
2020
View details for DOI 10.1111/btp.12864
View details for Web of Science ID 000575511100001
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Biodiversity and ecosystem services in the Campo Rupestre: A road map for the sustainability of the hottest Brazilian biodiversity hotspot
PERSPECTIVES IN ECOLOGY AND CONSERVATION
2020; 18 (4): 213–22
View details for DOI 10.1016/j.pecon.2020.10.004
View details for Web of Science ID 000605436800001
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Are protected populations of two globular cactus species facing a demographic explosion or just a "bonanza" year?
JOURNAL OF ARID ENVIRONMENTS
2020; 179
View details for DOI 10.1016/j.jaridenv.2020.104192
View details for Web of Science ID 000533505000001
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Early plant development depends on embryo damage location: the role of seed size in partial seed predation
OIKOS
2020; 129 (3): 320–30
View details for DOI 10.1111/oik.06912
View details for Web of Science ID 000517172500003
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A field experiment to determine the effect of dry-season irrigation on vegetative and reproductive traits in the wet-deciduous tree Bonellia nervosa
JOURNAL OF TROPICAL ECOLOGY
2020; 36 (1): 29–35
View details for DOI 10.1017/S0266467419000324
View details for Web of Science ID 000503968000004
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Distinct responses of antagonistic and mutualistic networks to agricultural intensification.
Ecology
2020: e03116
Abstract
Species interaction networks, which govern the maintenance of biodiversity and ecosystem processes within ecological communities, are being rapidly altered by anthropogenic activities worldwide. Studies on the response of species interaction networks to anthropogenic disturbance have almost exclusively focused on one interaction type at a time, such as mutualistic or antagonistic interactions, making it challenging to decipher how networks of different interaction types respond to the same anthropogenic disturbance. Moreover, few studies have simultaneously focused on the two main components of network structure: network topology (i.e. architecture) and network ecology (i.e. species identities and interaction turnover), thereby limiting our understanding of the ecological drivers underlying changes in network topology in response to anthropogenic disturbance. Here, we used 16,400 plant-pollinator and plant-herbivore interaction observations from 16 sites along an agricultural intensification gradient to compare changes in network topology and ecology between mutualistic and antagonistic networks. We measured two aspects of network topology - nestedness and modularity - and found that while the mutualistic networks were consistently more nested than antagonistic networks and antagonistic networks were consistently more modular, the rate of change in nestedness and modularity along the gradient was comparable between the two network types. Change in network ecology, however, was distinct between mutualistic and antagonistic networks, with partner switching making a significantly larger contribution to interaction turnover in the mutualistic networks than in the antagonistic networks, while species turnover was a strong contributor to interaction turnover in the antagonistic networks. The ecological and topological changes we observed in the antagonistic and mutualistic networks have different implications for pollinator and herbivore communities in agricultural landscapes, and support the idea that pollinators are more labile in their interaction partner choice whereas herbivores form more reciprocally specialized, and therefore more vulnerable, interactions. Our results also demonstrate that studying both topological and ecological network structure can help to elucidate the effects of anthropogenic disturbance on ecological communities, with applications for conservation and restoration of species interactions and the ecosystem processes they maintain.
View details for DOI 10.1002/ecy.3116
View details for PubMedID 32530504
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Agricultural intensification drives changes in hybrid network robustness by modifying network structure.
Ecology letters
2019
Abstract
Within ecological communities, species engage in myriad interaction types, yet empirical examples of hybrid species interaction networks composed of multiple types of interactions are still scarce. A key knowledge gap is understanding how the structure and stability of such hybrid networks are affected by anthropogenic disturbance. Using 15,169 interaction observations, we constructed 16 hybrid herbivore-plant-pollinator networks along an agricultural intensification gradient to explore changes in network structure and robustness to local extinctions. We found that agricultural intensification led to declines in modularity but increases in nestedness and connectance. Notably, network connectance, a structural feature typically thought to increase robustness, caused declines in hybrid network robustness, but the directionality of changes in robustness along the gradient depended on the order of local species extinctions. Our results not only demonstrate the impacts of anthropogenic disturbance on hybrid network structure, but they also provide unexpected insights into the structure-stability relationship of hybrid networks.
View details for DOI 10.1111/ele.13440
View details for PubMedID 31814265
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Spatio-temporal variation of biotic and abiotic stress agents determines seedling survival in assisted oak regeneration
JOURNAL OF APPLIED ECOLOGY
2019
View details for DOI 10.1111/1365-2664.13500
View details for Web of Science ID 000486931500001
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Host plant phylogeny and abundance predict root-associated fungal community composition and diversity of mutualists and pathogens
JOURNAL OF ECOLOGY
2019; 107 (4): 1557–66
View details for DOI 10.1111/1365-2745.13166
View details for Web of Science ID 000473096200003
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Nurse plant size and biotic stress determine quantity and quality of plant facilitation in oak savannas
FOREST ECOLOGY AND MANAGEMENT
2019; 437: 435–42
View details for DOI 10.1016/j.foreco.2019.02.010
View details for Web of Science ID 000461270600040
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An island of wildlife in a human-dominated landscape: The last fragment of primary forest on the Osa Peninsula's Golfo Dulce coastline, Costa Rica
PLOS ONE
2019; 14 (3)
View details for DOI 10.1371/journal.pone.0214390
View details for Web of Science ID 000462305600054
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Rodent community responses to vegetation and landscape changes in early successional stages of tropical dry forest
FOREST ECOLOGY AND MANAGEMENT
2019; 433: 633–44
View details for DOI 10.1016/j.foreco.2018.11.037
View details for Web of Science ID 000456902500064
- Peláez M, Dirzo R, Fernandes GW, Perea R. 2019. Nurse plant size and biotic stress determine quantity and quality of plant facilitation in oak savannas. Forest Ecology and Management 437: 435-442 Forest Ecology and Management 2019
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An island of wildlife in a human-dominated landscape: The last fragment of primary forest on the Osa Peninsula's Golfo Dulce coastline, Costa Rica.
PloS one
2019; 14 (3): e0214390
Abstract
Habitat loss and fragmentation, together with related edge effects, are the primary cause of global biodiversity decline. Despite a large amount of research quantifying and demonstrating the degree of these effects, particularly in top predators and their prey, most fragmented patches are lost before their conservation value is recognized. This study evaluates terrestrial vertebrates in Playa Sandalo, in the Osa Peninsula of Costa Rica, which represents the last patch of "primary" forest in the most developed part of this region. Our study indicates that the diversity of ground species detected within Playa Sandalo rival other areas under active conservation like Lapa Rios Ecolodge. Historical fragmentation, together with the maintenance of forest cover in isolated conditions, are potentially responsible for the species composition observed within Playa Sandalo; facilitating the development of a prey-predator system including ocelots, medium-size mammals, and birds at the top of the trophic chain. The high diversity of both habitat and vertebrates, its prime location and cultural value, as well as its unique marine importance represent the ideal conditions for conservation. Conservation of Playa Sandalo, and other small tropical forest remnants, might represent the only management option for wildlife conservation within ever growing human-dominated landscapes.
View details for PubMedID 30913255
- López Gutierrez, B., Almeyda Zambrano, A., Almeyda Zambrano, S. Quispe Gil, C.A., Avellan-Arias, E., Mulder, G., Ols, C. Dirzo, R., DeLuycker, A.M., Bohlman, S., Lewis, K., Broadbent, E.N. 2019. An island of wildlife in a human-dimionated landscape on the Osa Peninsula’s Golfo Dulce coastline, Costa Rica. PLoS One. 14(3): e0214390. https://doi.org/10.1371/journal. pone.0214390 PLoS One 2019
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Opening the silvicultural toolbox: A new framework for conserving biodiversity in Chilean timber plantations
FOREST ECOLOGY AND MANAGEMENT
2018; 425: 75–84
View details for DOI 10.1016/j.foreco.2018.05.028
View details for Web of Science ID 000438004500009
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Nature Divided, Scientists United: US-Mexico Border Wall Threatens Biodiversity and Binational Conservation
BIOSCIENCE
2018; 68 (10): 740–43
View details for DOI 10.1093/biosci/biy063
View details for Web of Science ID 000455168100003
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Invasive rat eradication strongly impacts plant recruitment on a tropical atoll
PLOS ONE
2018; 13 (7): e0200743
Abstract
Rat eradication has become a common conservation intervention in island ecosystems and its effectiveness in protecting native vertebrates is increasingly well documented. Yet, the impacts of rat eradication on plant communities remain poorly understood. Here we compare native and non-native tree and palm seedling abundance before and after eradication of invasive rats (Rattus rattus) from Palmyra Atoll, Line Islands, Central Pacific Ocean. Overall, seedling recruitment increased for five of the six native trees species examined. While pre-eradication monitoring found no seedlings of Pisonia grandis, a dominant tree species that is important throughout the Pacific region, post-eradication monitoring documented a notable recruitment event immediately following eradication, with up to 688 individual P. grandis seedlings per 100m2 recorded one month post-eradication. Two other locally rare native trees with no observed recruitment in pre-eradication surveys had recruitment post-rat eradication. However, we also found, by five years post-eradication, a 13-fold increase in recruitment of the naturalized and range-expanding coconut palm Cocos nucifera. Our results emphasize the strong effects that a rat eradication can have on tree recruitment with expected long-term effects on canopy composition. Rat eradication released non-native C. nucifera, likely with long-term implications for community composition, potentially necessitating future management interventions. Eradication, nevertheless, greatly benefitted recruitment of native tree species. If this pattern persists over time, we expect long-term benefits for flora and fauna dependent on these native species.
View details for PubMedID 30016347
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Assessing sustainability in North America's ecosystems using criticality and information theory
PLOS ONE
2018; 13 (7): e0200382
Abstract
Sustainability is a key concept in economic and policy debates. Nevertheless, it is usually treated only in a qualitative way and has eluded quantitative analysis. Here, we propose a sustainability index based on the premise that sustainable systems do not lose or gain Fisher Information over time. We test this approach using time series data from the AmeriFlux network that measures ecosystem respiration, water and energy fluxes in order to elucidate two key sustainability features: ecosystem health and stability. A novel definition of ecosystem health is developed based on the concept of criticality, which implies that if a system's fluctuations are scale invariant then the system is in a balance between robustness and adaptability. We define ecosystem stability by taking an information theory approach that measures its entropy and Fisher information. Analysis of the Ameriflux consortium big data set of ecosystem respiration time series is contrasted with land condition data. In general we find a good agreement between the sustainability index and land condition data. However, we acknowledge that the results are a preliminary test of the approach and further verification will require a multi-signal analysis. For example, high values of the sustainability index for some croplands are counter-intuitive and we interpret these results as ecosystems maintained in artificial health due to continuous human-induced inflows of matter and energy in the form of soil nutrients and control of competition, pests and disease.
View details for PubMedID 30011317
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Community composition and diversity of Neotropical root-associated fungi in common and rare trees
BIOTROPICA
2018; 50 (4): 694–703
View details for DOI 10.1111/btp.12553
View details for Web of Science ID 000437264200017
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Embryo size as a tolerance trait against seed predation: Contribution of embryo-damaged seeds to plant regeneration
PERSPECTIVES IN PLANT ECOLOGY EVOLUTION AND SYSTEMATICS
2018; 31: 7–16
View details for DOI 10.1016/j.ppees.2017.12.001
View details for Web of Science ID 000426206600002
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Cumulative effects of transgenerational induction on plant palatability to generalist and specialist herbivores
WEB ECOLOGY
2018; 18 (1): 41–46
View details for DOI 10.5194/we-18-41-2018
View details for Web of Science ID 000427964100001
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Anthropogenic food subsidies change the pattern of red fox diet and occurrence across Trans-Himalayas, India
JOURNAL OF ARID ENVIRONMENTS
2018; 150: 15–20
View details for DOI 10.1016/j.jaridenv.2017.12.011
View details for Web of Science ID 000424718100003
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Changes in livestock footprint and tree layer coverage in Mediterranean dehesas: a six-decade study based on remote sensing
INTERNATIONAL JOURNAL OF REMOTE SENSING
2018; 39 (14): 4727–43
View details for DOI 10.1080/01431161.2017.1365391
View details for Web of Science ID 000441646800010
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Differential tree recruitment in California oak savannas: Are evergreen oaks replacing deciduous oaks?
FOREST ECOLOGY AND MANAGEMENT
2017; 399: 1-8
View details for DOI 10.1016/j.foreco.2017.05.018
View details for Web of Science ID 000404195800001
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Biological annihilation via the ongoing sixth mass extinction signaled by vertebrate population losses and declines
PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA
2017; 114 (30): E6089–E6096
Abstract
The population extinction pulse we describe here shows, from a quantitative viewpoint, that Earth's sixth mass extinction is more severe than perceived when looking exclusively at species extinctions. Therefore, humanity needs to address anthropogenic population extirpation and decimation immediately. That conclusion is based on analyses of the numbers and degrees of range contraction (indicative of population shrinkage and/or population extinctions according to the International Union for Conservation of Nature) using a sample of 27,600 vertebrate species, and on a more detailed analysis documenting the population extinctions between 1900 and 2015 in 177 mammal species. We find that the rate of population loss in terrestrial vertebrates is extremely high-even in "species of low concern." In our sample, comprising nearly half of known vertebrate species, 32% (8,851/27,600) are decreasing; that is, they have decreased in population size and range. In the 177 mammals for which we have detailed data, all have lost 30% or more of their geographic ranges and more than 40% of the species have experienced severe population declines (>80% range shrinkage). Our data indicate that beyond global species extinctions Earth is experiencing a huge episode of population declines and extirpations, which will have negative cascading consequences on ecosystem functioning and services vital to sustaining civilization. We describe this as a "biological annihilation" to highlight the current magnitude of Earth's ongoing sixth major extinction event.
View details for PubMedID 28696295
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Interacting effects of land use and climate on rodent-borne pathogens in central Kenya
PHILOSOPHICAL TRANSACTIONS OF THE ROYAL SOCIETY B-BIOLOGICAL SCIENCES
2017; 372 (1722)
Abstract
Understanding the effects of anthropogenic disturbance on zoonotic disease risk is both a critical conservation objective and a public health priority. Here, we evaluate the effects of multiple forms of anthropogenic disturbance across a precipitation gradient on the abundance of pathogen-infected small mammal hosts in a multi-host, multi-pathogen system in central Kenya. Our results suggest that conversion to cropland and wildlife loss alone drive systematic increases in rodent-borne pathogen prevalence, but that pastoral conversion has no such systematic effects. The effects are most likely explained both by changes in total small mammal abundance, and by changes in relative abundance of a few high-competence species, although changes in vector assemblages may also be involved. Several pathogens responded to interactions between disturbance type and climatic conditions, suggesting the potential for synergistic effects of anthropogenic disturbance and climate change on the distribution of disease risk. Overall, these results indicate that conservation can be an effective tool for reducing abundance of rodent-borne pathogens in some contexts (e.g. wildlife loss alone); however, given the strong variation in effects across disturbance types, pathogen taxa and environmental conditions, the use of conservation as public health interventions will need to be carefully tailored to specific pathogens and human contexts.This article is part of the themed issue 'Conservation, biodiversity and infectious disease: scientific evidence and policy implications'.
View details for DOI 10.1098/rstb.2016.0116
View details for Web of Science ID 000399956400001
View details for PubMedID 28438909
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Forest conversion to cattle ranching differentially affects taxonomic and functional groups of Neotropical bats
BIOLOGICAL CONSERVATION
2017; 210: 343-348
View details for DOI 10.1016/j.biocon.2017.04.021
View details for Web of Science ID 000405881600038
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Cascading community and ecosystem consequences of introduced coconut palms (Cocos nucifera) in tropical islands
CANADIAN JOURNAL OF ZOOLOGY
2017; 95 (3): 139-148
View details for DOI 10.1139/cjz-2016-0107
View details for Web of Science ID 000398092400001
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Conserving the World's Megafauna and Biodiversity: The Fierce Urgency of Now
BIOSCIENCE
2017; 67 (3): 197-200
View details for Web of Science ID 000397164000003
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Merging paleobiology with conservation biology to guide the future of terrestrial ecosystems
SCIENCE
2017; 355 (6325): 594-?
Abstract
Conservation of species and ecosystems is increasingly difficult because anthropogenic impacts are pervasive and accelerating. Under this rapid global change, maximizing conservation success requires a paradigm shift from maintaining ecosystems in idealized past states toward facilitating their adaptive and functional capacities, even as species ebb and flow individually. Developing effective strategies under this new paradigm will require deeper understanding of the long-term dynamics that govern ecosystem persistence and reconciliation of conflicts among approaches to conserving historical versus novel ecosystems. Integrating emerging information from conservation biology, paleobiology, and the Earth sciences is an important step forward on the path to success. Maintaining nature in all its aspects will also entail immediately addressing the overarching threats of growing human population, overconsumption, pollution, and climate change.
View details for DOI 10.1126/science.aah4787
View details for PubMedID 28183912
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Species traits and interaction rules shape a species-rich seed-dispersal interaction network.
Ecology and evolution
2017; 7 (12): 4496–4506
Abstract
Species phenotypic traits affect the interaction patterns and the organization of seed-dispersal interaction networks. Understanding the relationship between species characteristics and network structure help us understand the assembly of natural communities and how communities function. Here, we examine how species traits may affect the rules leading to patterns of interaction among plants and fruit-eating vertebrates. We study a species-rich seed-dispersal system using a model selection approach to examine whether the rules underlying network structure are driven by constraints in fruit resource exploitation, by preferential consumption of fruits by the frugivores, or by a combination of both. We performed analyses for the whole system and for bird and mammal assemblages separately, and identified the animal and plant characteristics shaping interaction rules. The structure of the analyzed interaction network was better explained by constraints in resource exploitation in the case of birds and by preferential consumption of fruits with specific traits for mammals. These contrasting results when looking at bird-plant and mammal-plant interactions suggest that the same type of interaction is organized by different processes depending on the assemblage we focus on. Size-related restrictions of the interacting species (both for mammals and birds) were the most important factors driving the interaction rules. Our results suggest that the structure of seed-dispersal interaction networks can be explained using species traits and interaction rules related to simple ecological mechanisms.
View details for PubMedID 28649359
View details for PubMedCentralID PMC5478084
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Promoting the Educational Success of Children and Youth Learning English Promising Futures Summary
PROMOTING THE EDUCATIONAL SUCCESS OF CHILDREN AND YOUTH LEARNING ENGLISH: PROMISING FUTURES
2017: 1-+
Abstract
Amyloid plaques and neurofibrillary tangles (NFTs) in the brain are the neuropathological hallmarks of Alzheimer's disease (AD). Amyloid plaques are composed of β-amyloid peptides (Aβ), while NFTs contain hyperphosphorylated tau proteins. Patients with familial AD who have mutations in the amyloid precursor protein (APP) gene have either increased production of Aβ or generate more aggregation-prone forms of Aβ. The findings of familial AD mutations in the APP gene suggest that Aβ plays a central role in the pathophysiology of AD. Aβ42, composed of 42 amino acid residues, aggregates readily and is considered to form amyloid plaque. However, the processes of plaque formation are still not well known. It is generally thought that Aβ is secreted into the extracellular space and aggregates to form amyloid plaques. Aβ as extracellular aggregates and amyloid plaques are thought to be toxic to the surrounding neurons. The intraneuronal accumulation of Aβ has more recently been demonstrated and is reported to be involved in synaptic dysfunction, cognitive impairment, and the formation of amyloid plaques in AD. We herein provide an overview of the process of the intraneuronal accumulation of Aβ and plaque formation, and discuss its implications for the pathology, early diagnosis, and therapy of AD.
View details for Web of Science ID 000458481500001
View details for PubMedID 28261941
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Dual Language Learners and English Learners with Disabilities
PROMOTING THE EDUCATIONAL SUCCESS OF CHILDREN AND YOUTH LEARNING ENGLISH: PROMISING FUTURES
2017: 351–400
View details for Web of Science ID 000458481500011
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Policy Context
PROMOTING THE EDUCATIONAL SUCCESS OF CHILDREN AND YOUTH LEARNING ENGLISH: PROMISING FUTURES
2017: 37–61
View details for Web of Science ID 000458481500003
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The Development of English Language Proficiency in Grades K-12
PROMOTING THE EDUCATIONAL SUCCESS OF CHILDREN AND YOUTH LEARNING ENGLISH: PROMISING FUTURES
2017: 215–52
View details for Web of Science ID 000458481500007
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Promising and Effective Practices for Specific Populations of English Learners Grades Pre-K to 12
PROMOTING THE EDUCATIONAL SUCCESS OF CHILDREN AND YOUTH LEARNING ENGLISH: PROMISING FUTURES
2017: 337–50
View details for Web of Science ID 000458481500010
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Promising and Effective Practices in Assessment of Dual Language Learners' and English Learners' Educational Progress
PROMOTING THE EDUCATIONAL SUCCESS OF CHILDREN AND YOUTH LEARNING ENGLISH: PROMISING FUTURES
2017: 401–30
View details for Web of Science ID 000458481500012
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Promising and Effective Early Care and Education Practices and Home Visiting Programs for Dual Language Learners
PROMOTING THE EDUCATIONAL SUCCESS OF CHILDREN AND YOUTH LEARNING ENGLISH: PROMISING FUTURES
2017: 165–213
View details for Web of Science ID 000458481500006
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Recommendations for Policy, Practice, and Research
PROMOTING THE EDUCATIONAL SUCCESS OF CHILDREN AND YOUTH LEARNING ENGLISH: PROMISING FUTURES
2017: 471–85
View details for Web of Science ID 000458481500014
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Promoting the Educational Success of Children and Youth Learning English Promising Futures Introduction
PROMOTING THE EDUCATIONAL SUCCESS OF CHILDREN AND YOUTH LEARNING ENGLISH: PROMISING FUTURES
2017: 15–35
View details for Web of Science ID 000458481500002
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Programs for English Learners in Grades Pre-K to 12
PROMOTING THE EDUCATIONAL SUCCESS OF CHILDREN AND YOUTH LEARNING ENGLISH: PROMISING FUTURES
2017: 253–89
View details for Web of Science ID 000458481500008
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Promising and Effective Practices for English Learners in Grades Pre-K to 12
PROMOTING THE EDUCATIONAL SUCCESS OF CHILDREN AND YOUTH LEARNING ENGLISH: PROMISING FUTURES
2017: 291–335
View details for Web of Science ID 000458481500009
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Dual Language Learners: Capacities and Influences on Language Development
PROMOTING THE EDUCATIONAL SUCCESS OF CHILDREN AND YOUTH LEARNING ENGLISH: PROMISING FUTURES
2017: 107–63
View details for Web of Science ID 000458481500005
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Building the Workforce to Educate English Learners
PROMOTING THE EDUCATIONAL SUCCESS OF CHILDREN AND YOUTH LEARNING ENGLISH: PROMISING FUTURES
2017: 431–69
View details for Web of Science ID 000458481500013
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The Demography of the English Learner Population
PROMOTING THE EDUCATIONAL SUCCESS OF CHILDREN AND YOUTH LEARNING ENGLISH: PROMISING FUTURES
2017: 63–105
View details for Web of Science ID 000458481500004
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Patterns of orchid bee species diversity and turnover among forested plateaus of central Amazonia.
PloS one
2017; 12 (4): e0175884
Abstract
The knowledge of spatial pattern and geographic beta-diversity is of great importance for biodiversity conservation and interpreting ecological information. Tropical forests, especially the Amazon Rainforest, are well known for their high species richness and low similarity in species composition between sites, both at local and regional scales. We aimed to determine the effect and relative importance of area, isolation and climate on species richness and turnover in orchid bee assemblages among plateaus in central Brazilian Amazonia. Variance partitioning techniques were applied to assess the relative effects of spatial and environmental variables on bee species richness, phylogeny and composition. We hypothesized that greater abundance and richness of orchid bees would be found on larger plateaus, with a set of core species occurring on all of them. We also hypothesized that smaller plateaus would possess lower phylogenetic diversity. We found 55 bee species distributed along the nine sampling sites (plateaus) with 17 of them being singletons. There was a significant decrease in species richness with decreasing size of plateaus, and a significant decrease in the similarity in species composition with greater distance and climatic variation among sampling sites. Phylogenetic diversity varied among the sampling sites but was directly related to species richness. Although not significantly related to plateau area, smaller or larger PDFaith were observed in the smallest and the largest plateaus, respectively.
View details for PubMedID 28410432
View details for PubMedCentralID PMC5391963
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Saving the World's Terrestrial Megafauna
BIOSCIENCE
2016; 66 (10): 807-812
View details for DOI 10.1093/biosci/biw092
View details for Web of Science ID 000386485900003
View details for PubMedCentralID PMC5421308
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Saving the World's Terrestrial Megafauna.
Bioscience
2016; 66 (10): 807-812
View details for DOI 10.1093/biosci/biw092
View details for PubMedID 28533560
View details for PubMedCentralID PMC5421308
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Bushmeat hunting and extinction risk to the world's mammals
ROYAL SOCIETY OPEN SCIENCE
2016; 3 (10)
Abstract
Terrestrial mammals are experiencing a massive collapse in their population sizes and geographical ranges around the world, but many of the drivers, patterns and consequences of this decline remain poorly understood. Here we provide an analysis showing that bushmeat hunting for mostly food and medicinal products is driving a global crisis whereby 301 terrestrial mammal species are threatened with extinction. Nearly all of these threatened species occur in developing countries where major coexisting threats include deforestation, agricultural expansion, human encroachment and competition with livestock. The unrelenting decline of mammals suggests many vital ecological and socio-economic services that these species provide will be lost, potentially changing ecosystems irrevocably. We discuss options and current obstacles to achieving effective conservation, alongside consequences of failure to stem such anthropogenic mammalian extirpation. We propose a multi-pronged conservation strategy to help save threatened mammals from immediate extinction and avoid a collapse of food security for hundreds of millions of people.
View details for DOI 10.1098/rsos.160498
View details for Web of Science ID 000389241700035
View details for PubMedID 27853564
View details for PubMedCentralID PMC5098989
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Scattered trees and livestock grazing as keystones organisms for sustainable use and conservation of Mediterranean dehesas
JOURNAL FOR NATURE CONSERVATION
2016; 33: 58-67
View details for DOI 10.1016/j.jnc.2016.07.003
View details for Web of Science ID 000382125000007
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Post-dispersal seed recovery by animals: is it a plant- or an animal-driven process?
OIKOS
2016; 125 (8): 1203-1210
View details for DOI 10.1111/oik.02556
View details for Web of Science ID 000381207200015
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Deep into the mud: ecological and socio-economic impacts of the dam breach in Mariana, Brazil
NATUREZA & CONSERVACAO
2016; 14 (2): 35-45
View details for DOI 10.1016/j.ncon.2016.10.003
View details for Web of Science ID 000389961800001
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Afforestation of savannas: an impending ecological disaster
NATUREZA & CONSERVACAO
2016; 14 (2): 146-151
View details for DOI 10.1016/j.ncon.2016.08.002
View details for Web of Science ID 000389961800016
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Anthropogenic disturbances jeopardize biodiversity conservation within tropical rainforest reserves
PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA
2016; 113 (19): 5323-5328
Abstract
Anthropogenic disturbances affecting tropical forest reserves have been documented, but their ecological long-term cumulative effects are poorly understood. Habitat fragmentation and defaunation are two major anthropogenic threats to the integrity of tropical reserves. Based on a long-term (four decades) study, we document how these disturbances synergistically disrupt ecological processes and imperil biodiversity conservation and ecosystem functioning at Los Tuxtlas, the northernmost tropical rainforest reserve in the Americas. Deforestation around this reserve has reduced the reserve to a medium-sized fragment (640 ha), leading to an increased frequency of canopy-gap formation. In addition, hunting and habitat loss have caused the decline or local extinction of medium and large herbivores. Combining empirical, experimental, and modeling approaches, we support the hypothesis that such disturbances produced a demographic explosion of the long-lived (≈120 y old, maximum height of 7 m) understory palm Astrocaryum mexicanum, whose population has increased from 1,243-4,058 adult individuals per hectare in only 39 y (annual growth rate of ca 3%). Faster gap formation increased understory light availability, enhancing seed production and the growth of immature palms, whereas release from mammalian herbivory and trampling increased survival of seedlings and juveniles. In turn, the palm's demographic explosion was followed by a reduction of tree species diversity, changing forest composition, altering the relative contribution of trees to forest biomass, and disrupting litterfall dynamics. We highlight how indirect anthropogenic disturbances (e.g., palm proliferation) on otherwise protected areas threaten tropical conservation, a phenomenon that is currently eroding the planet's richest repositories of biodiversity.
View details for DOI 10.1073/pnas.1602893113
View details for Web of Science ID 000375478800062
View details for PubMedID 27071122
View details for PubMedCentralID PMC4868451
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Large wildlife removal drives immune defence increases in rodents
FUNCTIONAL ECOLOGY
2016; 30 (5): 799-807
View details for DOI 10.1111/1365-2435.12542
View details for Web of Science ID 000375941800014
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Does tropical forest fragmentation affect plant anti-herbivore defensive and nutritional traits?
JOURNAL OF TROPICAL ECOLOGY
2016; 32: 162-164
View details for DOI 10.1017/S0266467416000031
View details for Web of Science ID 000372522500008
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Livestock vs. wild ungulate management in the conservation of Mediterranean dehesas: Implications for oak regeneration
FOREST ECOLOGY AND MANAGEMENT
2016; 362: 99-106
View details for DOI 10.1016/j.foreco.2015.12.002
View details for Web of Science ID 000369556700011
- Does tropical forest fragmentation affect plant anti-herbivore defensive and nutritional traits? Journal of Tropical Ecology 2016; 32: 162-164
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Response: Commentary: Anthropogenic disturbances jeopardize biodiversity conservation within tropical rainforest reserves
FRONTIERS IN ECOLOGY AND EVOLUTION
2016; 4
View details for DOI 10.3389/fevo.2016.00108
View details for Web of Science ID 000517761700108
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Patterns, Causes, and Consequences of Anthropocene Defaunation
ANNUAL REVIEW OF ECOLOGY, EVOLUTION, AND SYSTEMATICS, VOL 47
2016; 47: 333-358
View details for DOI 10.1146/annurev-ecolsys-112414-054142
View details for Web of Science ID 000389576500015
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Hemiparasite-host plant interactions in a fragmented landscape assessed via imaging spectroscopy and LiDAR
ECOLOGICAL APPLICATIONS
2016; 26 (1): 55-66
Abstract
Species interactions are susceptible to anthropogenic changes in ecosystems, but this has been poorly investigated in a spatially explicit manner in the case of plant parasitism, such as the omnipresent hemiparasitic mistletoe-host plant interactions. Analyzing such interactions at a large spatial scale may advance our understanding of parasitism patterns over complex landscapes. Combining high-resolution airborne imaging spectroscopy and LiDAR, we studied hemiparasite incidence within and among tree host stands to examine the prevalence and spatial distribution of hemiparasite load in ecosystems. Specifically, we aimed to assess: (1) detection accuracy of mistletoes on their oak hosts; (2) hemiparasitism prevalence within host tree canopies depending on tree height, and (3) spatial variation in hemiparasitism across fragmented woodlands, in a low-diversity mediterranean oak woodland in California, USA. We identified mistletoe infestations with 55-96% accuracy, and detected significant differences in remote-sensed spectra between oak trees with and without mistletoe infestation. We also found that host canopy height had little influence on infestation degree, whereas landscape-level variation showed consistent; non-random patterns: isolated host trees had twice the infestation load than did trees located at the core of forest fragments. Overall, we found that canopy exposure (i.e., lower canopy density or proximity to forest edge) is more important than canopy height for mistletoe infestation, and that by changing landscape structure, parasitic prevalence increased with woodland fragmentation. We conclude that reducing fragmentation in oak woodlands will minimize anthropogenic impact on mistletoe infestation at the landscape level. We argue that advanced remote sensing technology can provide baselines to quantitatively analyze and monitor parasite-host trajectories in light of global environmental change, and that this is a promising approach to be further tested in other temperate and tropical forests.
View details for DOI 10.1890/14.2429
View details for Web of Science ID 000369511000006
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Genetics-based interactions among plants, pathogens, and herbivores define arthropod community structure
ECOLOGY
2015; 96 (7): 1974-1984
Abstract
Plant resistance to pathogens or insect herbivores is common, but its potential for indirectly influencing plant-associated communities is poorly known. Here, we test whether pathogens' indirect effects on arthropod communities and herbivory depend on plant resistance to pathogens and/or herbivores, and address the overarching interacting foundation species hypothesis that genetics-based interactions among a few highly interactive species can structure a much larger community. In a manipulative field experiment using replicated genotypes of two Populus species and their interspecific hybrids, we found that genetic variation in plant resistance to both pathogens and insect herbivores modulated the strength of pathogens' indirect effects on arthropod communities and insect herbivory. First, due in part to the pathogens' differential impacts on leaf biomass among the two Populus species and the hybrids, the pathogen most strongly impacted arthropod community composition, richness, and abundance on the pathogen-susceptible tree species. Second, we found similar patterns comparing pathogen-susceptible and pathogen-resistant genotypes within species. Third, within a plant species, pathogens caused a fivefold greater reduction in herbivory on insect-herbivore-susceptible plant genotypes than on herbivore-resistant genotypes, demonstrating that the pathogen-herbivore interaction is genotype dependent. We conclude that interactions among plants, pathogens, and herbivores can structure multitrophic communities, supporting the interacting foundation species hypothesis. Because these interactions are genetically based, evolutionary changes in genetic resistance could result in ecological changes in associated communities, which may in turn feed back to affect plant fitness.
View details for DOI 10.1890/13-2031.1
View details for Web of Science ID 000357525800024
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Genetics-based interactions among plants, pathogens, and herbivores define arthropod community structure.
Ecology
2015; 96 (7): 1974-1984
Abstract
Plant resistance to pathogens or insect herbivores is common, but its potential for indirectly influencing plant-associated communities is poorly known. Here, we test whether pathogens' indirect effects on arthropod communities and herbivory depend on plant resistance to pathogens and/or herbivores, and address the overarching interacting foundation species hypothesis that genetics-based interactions among a few highly interactive species can structure a much larger community. In a manipulative field experiment using replicated genotypes of two Populus species and their interspecific hybrids, we found that genetic variation in plant resistance to both pathogens and insect herbivores modulated the strength of pathogens' indirect effects on arthropod communities and insect herbivory. First, due in part to the pathogens' differential impacts on leaf biomass among the two Populus species and the hybrids, the pathogen most strongly impacted arthropod community composition, richness, and abundance on the pathogen-susceptible tree species. Second, we found similar patterns comparing pathogen-susceptible and pathogen-resistant genotypes within species. Third, within a plant species, pathogens caused a fivefold greater reduction in herbivory on insect-herbivore-susceptible plant genotypes than on herbivore-resistant genotypes, demonstrating that the pathogen-herbivore interaction is genotype dependent. We conclude that interactions among plants, pathogens, and herbivores can structure multitrophic communities, supporting the interacting foundation species hypothesis. Because these interactions are genetically based, evolutionary changes in genetic resistance could result in ecological changes in associated communities, which may in turn feed back to affect plant fitness.
View details for PubMedID 26378319
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Drivers of Intensity and Prevalence of Flea Parasitism on Small Mammals in East African Savanna Ecosystems.
journal of parasitology
2015; 101 (3): 327-335
Abstract
The relative importance of environmental factors and host factors in explaining variation in prevalence and intensity of flea parasitism in small mammal communities is poorly established. We examined these relationships in an East African savanna landscape, considering multiple host levels: across individuals within a local population, across populations within species, and across species within a landscape. We sampled fleas from 2,672 small mammals of 27 species. This included a total of 8,283 fleas, with 5 genera and 12 species identified. Across individual hosts within a site, both rodent body mass and season affected total intensity of flea infestation, although the explanatory power of these factors was generally modest (<10%). Across host populations in the landscape, we found consistently positive effects of host density and negative effects of vegetation cover on the intensity of flea infestation. Other factors explored (host diversity, annual rainfall, anthropogenic disturbance, and soil properties) tended to have lower and less consistent explanatory power. Across host species in the landscape, we found that host body mass was strongly positively correlated with both prevalence and intensity of flea parasitism, while average robustness of a host species to disturbance was not correlated with flea parasitism. Cumulatively, these results provide insight into the intricate roles of both host and environmental factors in explaining complex patterns of flea parasitism across landscape mosaics.
View details for DOI 10.1645/14-684.1
View details for PubMedID 25634599
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DRIVERS OF INTENSITY AND PREVALENCE OF FLEA PARASITISM ON SMALL MAMMALS IN EAST AFRICAN SAVANNA ECOSYSTEMS
JOURNAL OF PARASITOLOGY
2015; 101 (3): 327-335
Abstract
The relative importance of environmental factors and host factors in explaining variation in prevalence and intensity of flea parasitism in small mammal communities is poorly established. We examined these relationships in an East African savanna landscape, considering multiple host levels: across individuals within a local population, across populations within species, and across species within a landscape. We sampled fleas from 2,672 small mammals of 27 species. This included a total of 8,283 fleas, with 5 genera and 12 species identified. Across individual hosts within a site, both rodent body mass and season affected total intensity of flea infestation, although the explanatory power of these factors was generally modest (<10%). Across host populations in the landscape, we found consistently positive effects of host density and negative effects of vegetation cover on the intensity of flea infestation. Other factors explored (host diversity, annual rainfall, anthropogenic disturbance, and soil properties) tended to have lower and less consistent explanatory power. Across host species in the landscape, we found that host body mass was strongly positively correlated with both prevalence and intensity of flea parasitism, while average robustness of a host species to disturbance was not correlated with flea parasitism. Cumulatively, these results provide insight into the intricate roles of both host and environmental factors in explaining complex patterns of flea parasitism across landscape mosaics.
View details for DOI 10.1645/14-684.1
View details for Web of Science ID 000356539600009
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Collapse of the world's largest herbivores.
Science advances
2015; 1 (4)
Abstract
Large wild herbivores are crucial to ecosystems and human societies. We highlight the 74 largest terrestrial herbivore species on Earth (body mass ≥100 kg), the threats they face, their important and often overlooked ecosystem effects, and the conservation efforts needed to save them and their predators from extinction. Large herbivores are generally facing dramatic population declines and range contractions, such that ~60% are threatened with extinction. Nearly all threatened species are in developing countries, where major threats include hunting, land-use change, and resource depression by livestock. Loss of large herbivores can have cascading effects on other species including large carnivores, scavengers, mesoherbivores, small mammals, and ecological processes involving vegetation, hydrology, nutrient cycling, and fire regimes. The rate of large herbivore decline suggests that ever-larger swaths of the world will soon lack many of the vital ecological services these animals provide, resulting in enormous ecological and social costs.
View details for DOI 10.1126/sciadv.1400103
View details for PubMedID 26601172
View details for PubMedCentralID PMC4640652
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Effects of Land Use on Plague (Yersinia pestis) Activity in Rodents in Tanzania
AMERICAN JOURNAL OF TROPICAL MEDICINE AND HYGIENE
2015; 92 (4): 776-783
Abstract
Understanding the effects of land-use change on zoonotic disease risk is a pressing global health concern. Here, we compare prevalence of Yersinia pestis, the etiologic agent of plague, in rodents across two land-use types-agricultural and conserved-in northern Tanzania. Estimated abundance of seropositive rodents nearly doubled in agricultural sites compared with conserved sites. This relationship between land-use type and abundance of seropositive rodents is likely mediated by changes in rodent and flea community composition, particularly via an increase in the abundance of the commensal species, Mastomys natalensis, in agricultural habitats. There was mixed support for rodent species diversity negatively impacting Y. pestis seroprevalence. Together, these results suggest that land-use change could affect the risk of local transmission of plague, and raise critical questions about transmission dynamics at the interface of conserved and agricultural habitats. These findings emphasize the importance of understanding disease ecology in the context of rapidly proceeding landscape change.
View details for DOI 10.4269/ajtmh.14-0504
View details for Web of Science ID 000352828200018
View details for PubMedID 25711606
View details for PubMedCentralID PMC4385772
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Tropical Forest Fragmentation Affects Floral Visitors but Not the Structure of Individual-Based Palm-Pollinator Networks
PLOS ONE
2015; 10 (3)
Abstract
Despite increasing knowledge about the effects of habitat loss on pollinators in natural landscapes, information is very limited regarding the underlying mechanisms of forest fragmentation affecting plant-pollinator interactions in such landscapes. Here, we used a network approach to describe the effects of forest fragmentation on the patterns of interactions involving the understory dominant palm Astrocaryum mexicanum (Arecaceae) and its floral visitors (including both effective and non-effective pollinators) at the individual level in a Mexican tropical rainforest landscape. Specifically, we asked: (i) Does fragment size affect the structure of individual-based plant-pollinator networks? (ii) Does the core of highly interacting visitor species change along the fragmentation size gradient? (iii) Does forest fragment size influence the abundance of effective pollinators of A. mexicanum? We found that fragment size did not affect the topological structure of the individual-based palm-pollinator network. Furthermore, while the composition of peripheral non-effective pollinators changed depending on fragment size, effective core generalist species of pollinators remained stable. We also observed that both abundance and variance of effective pollinators of male and female flowers of A. mexicanum increased with forest fragment size. These findings indicate that the presence of effective pollinators in the core of all forest fragments could keep the network structure stable along the gradient of forest fragmentation. In addition, pollination of A. mexicanum could be more effective in larger fragments, since the greater abundance of pollinators in these fragments may increase the amount of pollen and diversity of pollen donors between flowers of individual plants. Given the prevalence of fragmentation in tropical ecosystems, our results indicate that the current patterns of land use will have consequences on the underlying mechanisms of pollination in remnant forests.
View details for DOI 10.1371/journal.pone.0121275
View details for Web of Science ID 000352084800039
View details for PubMedID 25826702
View details for PubMedCentralID PMC4380365
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RELEVANT ASPECTS ABOUT THE NATURAL HISTORY OF STRANGLER HEMIEPIPHYTE PLANTS
INTERCIENCIA
2015; 40 (3): 190-197
View details for Web of Science ID 000351892000007
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Context-dependent effects of large-wildlife declines on small-mammal communities in central Kenya.
Ecological applications
2015; 25 (2): 348-360
Abstract
Many species of large wildlife have declined drastically worldwide. These reductions often lead to profound shifts in the ecology of entire communities and ecosystems. However, the effects of these large-wildlife declines on other taxa likely hinge upon both underlying abiotic properties of these systems and on the types of secondary anthropogenic changes associated with wildlife loss, making impacts difficult to predict. To better understand how these important contextual factors determine the consequences of large-wildlife declines on other animals in a community, we examined the effects of three common forms of large-wildlife loss (removal without replacement [using fences], removal followed by replacement with domestic stock, and removal accompanied by crop agricultural use) on small-mammal abundance, diversity, and community composition, in landscapes that varied in several abiotic attributes (rainfall, soil fertility, land-use intensity) in central Kenya. We found that small-mammal communities were indeed heavily impacted by all forms of large-wildlife decline, showing, on average: (1) higher densities, (2) lower species richness per site, and (3) different species assemblages in sites from which large wildlife were removed. However, the nature and magnitude of these effects were strongly context dependent. Rainfall, type of land-use change, and the interaction of these two factors were key predictors of both the magnitude and type of responses of small mammals. The strongest effects, particularly abundance responses, tended to be observed in low-rainfall areas. Whereas isolated wildlife removal primarily led to increased small-mammal abundance, wildlife removal associated with secondary uses (agriculture, domestic stock) had much more variable effects on abundance and stronger impacts on diversity and composition. Collectively, these results (1) highlight the importance of context in determining the impacts of large-wildlife decline on small-mammal communities, (2) emphasize the challenges in extrapolating results from controlled experimental studies to predict the effects of wildlife declines that are accompanied by secondary land-uses, and (3) suggest that, because of the context-dependent nature of the responses to large-wildlife decline, large-wildlife status alone cannot be reliably used to predict small-mammal community changes.
View details for PubMedID 26263659
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Context-dependent effects of large-wildlife declines on small-mammal communities in central Kenya
ECOLOGICAL APPLICATIONS
2015; 25 (2): 348-360
Abstract
Many species of large wildlife have declined drastically worldwide. These reductions often lead to profound shifts in the ecology of entire communities and ecosystems. However, the effects of these large-wildlife declines on other taxa likely hinge upon both underlying abiotic properties of these systems and on the types of secondary anthropogenic changes associated with wildlife loss, making impacts difficult to predict. To better understand how these important contextual factors determine the consequences of large-wildlife declines on other animals in a community, we examined the effects of three common forms of large-wildlife loss (removal without replacement [using fences], removal followed by replacement with domestic stock, and removal accompanied by crop agricultural use) on small-mammal abundance, diversity, and community composition, in landscapes that varied in several abiotic attributes (rainfall, soil fertility, land-use intensity) in central Kenya. We found that small-mammal communities were indeed heavily impacted by all forms of large-wildlife decline, showing, on average: (1) higher densities, (2) lower species richness per site, and (3) different species assemblages in sites from which large wildlife were removed. However, the nature and magnitude of these effects were strongly context dependent. Rainfall, type of land-use change, and the interaction of these two factors were key predictors of both the magnitude and type of responses of small mammals. The strongest effects, particularly abundance responses, tended to be observed in low-rainfall areas. Whereas isolated wildlife removal primarily led to increased small-mammal abundance, wildlife removal associated with secondary uses (agriculture, domestic stock) had much more variable effects on abundance and stronger impacts on diversity and composition. Collectively, these results (1) highlight the importance of context in determining the impacts of large-wildlife decline on small-mammal communities, (2) emphasize the challenges in extrapolating results from controlled experimental studies to predict the effects of wildlife declines that are accompanied by secondary land-uses, and (3) suggest that, because of the context-dependent nature of the responses to large-wildlife decline, large-wildlife status alone cannot be reliably used to predict small-mammal community changes.
View details for DOI 10.1890/14-0995.1
View details for Web of Science ID 000350556400004
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Experimental defaunation of terrestrial mammalian herbivores alters tropical rainforest understorey diversity.
Proceedings. Biological sciences / The Royal Society
2015; 282 (1800)
Abstract
It has been suggested that tropical defaunation may unleash community-wide cascading effects, leading to reductions in plant diversity. However, experimental evidence establishing cause-effect relationships thereof is poor. Through a 5 year exclosure experiment, we tested the hypothesis that mammalian defaunation affects tree seedling/sapling community dynamics leading to reductions in understorey plant diversity. We established plot triplets (n = 25) representing three defaunation contexts: terrestrial-mammal exclosure (TE), medium/large mammal exclosure (PE) and open access controls (C). Seedlings/saplings 30-100 cm tall were marked and identified within each of these plots and re-censused three times to record survival and recruitment. In the periods 2010-2011 and 2011-2013, survival was greater in PE than in C plots and recruitment was higher in TE plots than in C plots. Overall, seedling density increased by 61% in TE plots and 23% in PE plots, whereas it decreased by 5% in C plots. Common species highly consumed by mammals (e.g. Brosimum alicastrum and Ampelocera hottlei) increased in their abundance in TE plots. Rarefaction curves showed that species diversity decreased in TE plots from 2008 to 2013, whereas it remained similar for C plots. Given the prevalence of tropical defaunation, we posit this is an anthropogenic effect threatening the maintenance of tropical forest diversity.
View details for DOI 10.1098/rspb.2014.2580
View details for PubMedID 25540281
View details for PubMedCentralID PMC4298212
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Strategic Actions to Value, Conserve, and Restore the Natural Capital of Megadiversity Countries: The Case of Mexico
BIOSCIENCE
2015; 65 (2): 164-173
Abstract
Decisionmakers need updated, scientifically sound and relevant information to implement appropriate policy measures and make innovative commitments to halt biodiversity loss and improve human well-being. Here, we present a recent science-based synthesis on the biodiversity and ecosystem services of Mexico, intended to be a tool for policymakers. We describe the methodological approach used to undertake such an assessment and highlight the major findings. Organized into five volumes and originally written in Spanish (Capital Natural de México), it summarizes the available knowledge on the components, structure, and functioning of the biodiversity of Mexico; the threats and trajectories of anthropogenic impact, together with its conservation status; and the policies, institutions, and instruments available for its sustainable management. We stress the lessons learned that can be useful for similar exercises in other megadiverse developing countries and identify major gaps and strategic actions to conserve the natural capital in light of the challenges of the Anthropocene.
View details for DOI 10.1093/biosci/biu195
View details for Web of Science ID 000348973600011
View details for PubMedCentralID PMC4778169
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Strategic Actions to Value, Conserve, and Restore the Natural Capital of Megadiversity Countries: The Case of Mexico.
Bioscience
2015; 65 (2): 164-173
Abstract
Decisionmakers need updated, scientifically sound and relevant information to implement appropriate policy measures and make innovative commitments to halt biodiversity loss and improve human well-being. Here, we present a recent science-based synthesis on the biodiversity and ecosystem services of Mexico, intended to be a tool for policymakers. We describe the methodological approach used to undertake such an assessment and highlight the major findings. Organized into five volumes and originally written in Spanish (Capital Natural de México), it summarizes the available knowledge on the components, structure, and functioning of the biodiversity of Mexico; the threats and trajectories of anthropogenic impact, together with its conservation status; and the policies, institutions, and instruments available for its sustainable management. We stress the lessons learned that can be useful for similar exercises in other megadiverse developing countries and identify major gaps and strategic actions to conserve the natural capital in light of the challenges of the Anthropocene.
View details for DOI 10.1093/biosci/biu195
View details for PubMedID 26955077
View details for PubMedCentralID PMC4778169
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Habitat Heterogeneity Affects Plant and Arthropod Species Diversity and Turnover in Traditional Cornfields.
PloS one
2015; 10 (7): e0128950
Abstract
The expansion of the agricultural frontier by the clearing of remnant forests has led to human-dominated landscape mosaics. Previous studies have evaluated the effect of these landscape mosaics on arthropod diversity at local spatial scales in temperate and tropical regions, but little is known about fragmentation effects in crop systems, such as the complex tropical traditional crop systems that maintain a high diversity of weeds and arthropods in low-Andean regions. To understand the factors that influence patterns of diversity in human-dominated landscapes, we investigate the effect of land use types on plant and arthropod diversity in traditionally managed cornfields, via surveys of plants and arthropods in twelve traditional cornfields in the Colombian Andes. We estimated alpha and beta diversity to analyze changes in diversity related to land uses within a radius of 100 m to 1 km around each cornfield. We observed that forests influenced alpha diversity of plants, but not of arthropods. Agricultural lands had a positive relationship with plants and herbivores, but a negative relationship with predators. Pastures positively influenced the diversity of plants and arthropods. In addition, forest cover seemed to influence changes in plant species composition and species turnover of herbivore communities among cornfields. The dominant plant species varied among fields, resulting in high differentiation of plant communities. Predator communities also exhibited high turnover among cornfields, but differences in composition arose mainly among rare species. The crop system evaluated in this study represents a widespread situation in the tropics, therefore, our results can be of broad significance. Our findings suggest that traditional agriculture may not homogenize biological communities, but instead could maintain the regional pool of species through high beta diversity.
View details for PubMedID 26197473
View details for PubMedCentralID PMC4510542
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Long-term vegetation changes in a temperate forest impacted by climate change
ECOSPHERE
2014; 5 (10)
View details for DOI 10.1890/ES14-00225.1
View details for Web of Science ID 000345097200013
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Differentiating genetic and environmental drivers of plant-pathogen community interactions
JOURNAL OF ECOLOGY
2014; 102 (5): 1300-1309
View details for DOI 10.1111/1365-2745.12270
View details for Web of Science ID 000340681300020
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Reconstructing past ecological networks: the reconfiguration of seed-dispersal interactions after megafaunal extinction.
Oecologia
2014; 175 (4): 1247-1256
Abstract
The late Quaternary megafaunal extinction impacted ecological communities worldwide, and affected key ecological processes such as seed dispersal. The traits of several species of large-seeded plants are thought to have evolved in response to interactions with extinct megafauna, but how these extinctions affected the organization of interactions in seed-dispersal systems is poorly understood. Here, we combined ecological and paleontological data and network analyses to investigate how the structure of a species-rich seed-dispersal network could have changed from the Pleistocene to the present and examine the possible consequences of such changes. Our results indicate that the seed-dispersal network was organized into modules across the different time periods but has been reconfigured in different ways over time. The episode of megafaunal extinction and the arrival of humans changed how seed dispersers were distributed among network modules. However, the recent introduction of livestock into the seed-dispersal system partially restored the original network organization by strengthening the modular configuration. Moreover, after megafaunal extinctions, introduced species and some smaller native mammals became key components for the structure of the seed-dispersal network. We hypothesize that such changes in network structure affected both animal and plant assemblages, potentially contributing to the shaping of modern ecological communities. The ongoing extinction of key large vertebrates will lead to a variety of context-dependent rearranged ecological networks, most certainly affecting ecological and evolutionary processes.
View details for DOI 10.1007/s00442-014-2971-1
View details for PubMedID 24865393
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Translating science for decision makers to help navigate the Anthropocene
ANTHROPOCENE REVIEW
2014; 1 (2): 160-170
View details for DOI 10.1177/2053019614533670
View details for Web of Science ID 000447102300006
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Defaunation in the Anthropocene
SCIENCE
2014; 345 (6195): 401-406
Abstract
We live amid a global wave of anthropogenically driven biodiversity loss: species and population extirpations and, critically, declines in local species abundance. Particularly, human impacts on animal biodiversity are an under-recognized form of global environmental change. Among terrestrial vertebrates, 322 species have become extinct since 1500, and populations of the remaining species show 25% average decline in abundance. Invertebrate patterns are equally dire: 67% of monitored populations show 45% mean abundance decline. Such animal declines will cascade onto ecosystem functioning and human well-being. Much remains unknown about this "Anthropocene defaunation"; these knowledge gaps hinder our capacity to predict and limit defaunation impacts. Clearly, however, defaunation is both a pervasive component of the planet's sixth mass extinction and also a major driver of global ecological change.
View details for DOI 10.1126/science.1251817
View details for Web of Science ID 000339655100031
View details for PubMedID 25061202
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Declines in large wildlife increase landscape-level prevalence of rodent-borne disease in Africa
PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA
2014; 111 (19): 7036-7041
Abstract
Populations of large wildlife are declining on local and global scales. The impacts of this pulse of size-selective defaunation include cascading changes to smaller animals, particularly rodents, and alteration of many ecosystem processes and services, potentially involving changes to prevalence and transmission of zoonotic disease. Understanding linkages between biodiversity loss and zoonotic disease is important for both public health and nature conservation programs, and has been a source of much recent scientific debate. In the case of rodent-borne zoonoses, there is strong conceptual support, but limited empirical evidence, for the hypothesis that defaunation, the loss of large wildlife, increases zoonotic disease risk by directly or indirectly releasing controls on rodent density. We tested this hypothesis by experimentally excluding large wildlife from a savanna ecosystem in East Africa, and examining changes in prevalence and abundance of Bartonella spp. infection in rodents and their flea vectors. We found no effect of wildlife removal on per capita prevalence of Bartonella infection in either rodents or fleas. However, because rodent and, consequently, flea abundance doubled following experimental defaunation, the density of infected hosts and infected fleas was roughly twofold higher in sites where large wildlife was absent. Thus, defaunation represents an elevated risk in Bartonella transmission to humans (bartonellosis). Our results (i) provide experimental evidence of large wildlife defaunation increasing landscape-level disease prevalence, (ii) highlight the importance of susceptible host regulation pathways and host/vector density responses in biodiversity-disease relationships, and (iii) suggest that rodent-borne disease responses to large wildlife loss may represent an important context where this relationship is largely negative.
View details for DOI 10.1073/pnas.1404958111
View details for Web of Science ID 000335798000068
View details for PubMedID 24778215
View details for PubMedCentralID PMC4024866
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Differential plant damage due to litterfall in palm-dominated forest stands in a Central Pacific atoll
JOURNAL OF TROPICAL ECOLOGY
2014; 30: 231-236
View details for DOI 10.1017/S026646741400008X
View details for Web of Science ID 000337762600006
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Introducing the Scientific Consensus on Maintaining Humanity's Life Support Systems in the 21 st Century: Information for Policy Makers
ANTHROPOCENE REVIEW
2014; 1 (1): 78–109
View details for DOI 10.1177/2053019613516290
View details for Web of Science ID 000447092100009
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Integrating stand and soil properties to understand foliar nutrient dynamics during forest succession following slash-and-burn agriculture in the Bolivian Amazon.
PloS one
2014; 9 (2)
Abstract
Secondary forests cover large areas of the tropics and play an important role in the global carbon cycle. During secondary forest succession, simultaneous changes occur among stand structural attributes, soil properties, and species composition. Most studies classify tree species into categories based on their regeneration requirements. We use a high-resolution secondary forest chronosequence to assign trees to a continuous gradient in species successional status assigned according to their distribution across the chronosequence. Species successional status, not stand age or differences in stand structure or soil properties, was found to be the best predictor of leaf trait variation. Foliar δ(13)C had a significant positive relationship with species successional status, indicating changes in foliar physiology related to growth and competitive strategy, but was not correlated with stand age, whereas soil δ(13)C dynamics were largely constrained by plant species composition. Foliar δ(15)N had a significant negative correlation with both stand age and species successional status, - most likely resulting from a large initial biomass-burning enrichment in soil (15)N and (13)C and not closure of the nitrogen cycle. Foliar %C was neither correlated with stand age nor species successional status but was found to display significant phylogenetic signal. Results from this study are relevant to understanding the dynamics of tree species growth and competition during forest succession and highlight possibilities of, and potentially confounding signals affecting, the utility of leaf traits to understand community and species dynamics during secondary forest succession.
View details for DOI 10.1371/journal.pone.0086042
View details for PubMedID 24516525
View details for PubMedCentralID PMC3917844
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Effects of cattle management on oak regeneration in northern californian mediterranean oak woodlands.
PloS one
2014; 9 (8)
Abstract
Oak woodlands of Mediterranean ecosystems, a major component of biodiversity hotspots in Europe and North America, have undergone significant land-use change in recent centuries, including an increase in grazing intensity due to the widespread presence of cattle. Simultaneously, a decrease in oak regeneration has been observed, suggesting a link between cattle grazing intensity and limited oak regeneration. In this study we examined the effect of cattle grazing on coast live oak (Quercus agrifolia Née) regeneration in San Francisco Bay Area, California. We studied seedling, sapling and adult density of coast live oak as well as vertebrate herbivory at 8 independent sites under two grazing conditions: with cattle and wildlife presence (n = 4) and only with wildlife (n = 4). The specific questions we addressed are: i) to what extent cattle management practices affect oak density, and ii) what is the effect of rangeland management on herbivory and size of young oak plants. In areas with cattle present, we found a 50% reduction in young oak density, and plant size was smaller, suggesting that survival and growth young plants in those areas are significantly limited. In addition, the presence of cattle raised the probability and intensity of herbivory (a 1.5 and 1.8-fold difference, respectively). These results strongly suggest that the presence of cattle significantly reduced the success of young Q. agrifolia through elevated herbivory. Given the potential impact of reduced recruitment on adult populations, modifying rangeland management practices to reduce cattle grazing pressure seems to be an important intervention to maintain Mediterranean oak woodlands.
View details for DOI 10.1371/journal.pone.0105472
View details for PubMedID 25126939
View details for PubMedCentralID PMC4134313
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Integrating Stand and Soil Properties to Understand Foliar Nutrient Dynamics during Forest Succession Following Slash-and-Burn Agriculture in the Bolivian Amazon.
PloS one
2014; 9 (2): e86042
Abstract
Secondary forests cover large areas of the tropics and play an important role in the global carbon cycle. During secondary forest succession, simultaneous changes occur among stand structural attributes, soil properties, and species composition. Most studies classify tree species into categories based on their regeneration requirements. We use a high-resolution secondary forest chronosequence to assign trees to a continuous gradient in species successional status assigned according to their distribution across the chronosequence. Species successional status, not stand age or differences in stand structure or soil properties, was found to be the best predictor of leaf trait variation. Foliar δ(13)C had a significant positive relationship with species successional status, indicating changes in foliar physiology related to growth and competitive strategy, but was not correlated with stand age, whereas soil δ(13)C dynamics were largely constrained by plant species composition. Foliar δ(15)N had a significant negative correlation with both stand age and species successional status, - most likely resulting from a large initial biomass-burning enrichment in soil (15)N and (13)C and not closure of the nitrogen cycle. Foliar %C was neither correlated with stand age nor species successional status but was found to display significant phylogenetic signal. Results from this study are relevant to understanding the dynamics of tree species growth and competition during forest succession and highlight possibilities of, and potentially confounding signals affecting, the utility of leaf traits to understand community and species dynamics during secondary forest succession.
View details for DOI 10.1371/journal.pone.0086042
View details for PubMedID 24516525
View details for PubMedCentralID PMC3917844
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Water stress strengthens mutualism among ants, trees, and scale insects.
PLoS biology
2013; 11 (11)
Abstract
Abiotic environmental variables strongly affect the outcomes of species interactions. For example, mutualistic interactions between species are often stronger when resources are limited. The effect might be indirect: water stress on plants can lead to carbon stress, which could alter carbon-mediated plant mutualisms. In mutualistic ant-plant symbioses, plants host ant colonies that defend them against herbivores. Here we show that the partners' investments in a widespread ant-plant symbiosis increase with water stress across 26 sites along a Mesoamerican precipitation gradient. At lower precipitation levels, Cordia alliodora trees invest more carbon in Azteca ants via phloem-feeding scale insects that provide the ants with sugars, and the ants provide better defense of the carbon-producing leaves. Under water stress, the trees have smaller carbon pools. A model of the carbon trade-offs for the mutualistic partners shows that the observed strategies can arise from the carbon costs of rare but extreme events of herbivory in the rainy season. Thus, water limitation, together with the risk of herbivory, increases the strength of a carbon-based mutualism.
View details for DOI 10.1371/journal.pbio.1001705
View details for PubMedID 24223521
View details for PubMedCentralID PMC3818173
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Richness and Abundance of Ichneumonidae in a Fragmented Tropical Rain Forest
NEOTROPICAL ENTOMOLOGY
2013; 42 (5): 458-465
View details for DOI 10.1007/s13744-013-0143-3
View details for Web of Science ID 000324640300003
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Consumer preference for seeds and seedlings of rare species impacts tree diversity at multiple scales
OECOLOGIA
2013; 172 (3): 857-867
Abstract
Positive density-dependent seed and seedling predation, where herbivores selectively eat seeds or seedlings of common species, is thought to play a major role in creating and maintaining plant community diversity. However, many herbivores and seed predators are known to exhibit preferences for rare foods, which could lead to negative density-dependent predation. In this study, we first demonstrate the occurrence of increased predation of locally rare tree species by a widespread group of insular seed and seedling predators, land crabs. We then build computer simulations based on these empirical data to examine the effects of such predation on diversity patterns. Simulations show that herbivore preferences for locally rare species are likely to drive scale-dependent effects on plant community diversity: at small scales these foraging patterns decrease plant community diversity via the selective consumption of rare plant species, while at the landscape level they should increase diversity, at least for short periods, by promoting clustered local dominance of a variety of species. Finally, we compared observed patterns of plant diversity at the site to those obtained via computer simulations, and found that diversity patterns generated under simulations were highly consistent with observed diversity patterns. We posit that preference for rare species by herbivores may be prevalent in low- or moderate-diversity systems, and that these effects may help explain diversity patterns across different spatial scales in such ecosystems.
View details for DOI 10.1007/s00442-012-2542-2
View details for Web of Science ID 000320409100021
View details for PubMedID 23229391
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Effects of mammalian herbivore declines on plant communities: observations and experiments in an African savanna.
The Journal of ecology
2013; 101 (4): 1030-1041
Abstract
1. Herbivores influence the structure and composition of terrestrial plant communities. However, responses of plant communities to herbivory are variable and depend on environmental conditions, herbivore identity and herbivore abundance. As anthropogenic impacts continue to drive large declines in wild herbivores, understanding the context dependence of herbivore impacts on plant communities becomes increasingly important. 2. Exclosure experiments are frequently used to assess how ecosystems reorganize in the face of large wild herbivore defaunation. Yet in many landscapes, declines in large wildlife are often accompanied by other anthropogenic activities, especially land conversion to livestock production. In such cases, exclosure experiments may not reflect typical outcomes of human-driven extirpations of wild herbivores. 3. Here, we examine how plant community responses to changes in the identity and abundance of large herbivores interact with abiotic factors (rainfall and soil properties). We also explore how effects of wild herbivores on plant communities differ between large-scale herbivore exclosures and landscape sites where anthropogenic activity has caused wildlife declines, often accompanied by livestock increases. 4. Abiotic context modulated the responses of plant communities to herbivore declines with stronger effect sizes in lower-productivity environments. Also, shifts in plant community structure, composition and species richness following wildlife declines differed considerably between exclosure experiments and landscape sites in which wild herbivores had declined and were often replaced by livestock. Plant communities in low wildlife landscape sites were distinct in both composition and physical structure from both exclosure and control sites in experiments. The power of environmental (soil and rainfall) gradients in influencing plant response to herbivores was also greatly dampened or absent in the landscape sites. One likely explanation for these observed differences is the compensatory effect of livestock associated with the depression or extirpation of wildlife. 5.Synthesis. Our results emphasize the importance of abiotic environmental heterogeneity in modulating the effects of mammalian herbivory on plant communities and the importance of such covariation in understanding effects of wild herbivore declines. They also suggest caution when extrapolating results from exclosure experiments to predict the consequences of defaunation as it proceeds in the Anthropocene.
View details for DOI 10.1111/1365-2745.12096
View details for PubMedID 24014216
View details for PubMedCentralID PMC3758959
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Effects of mammalian herbivore declines on plant communities: observations and experiments in an African savanna
JOURNAL OF ECOLOGY
2013; 101 (4): 1030-1041
Abstract
1. Herbivores influence the structure and composition of terrestrial plant communities. However, responses of plant communities to herbivory are variable and depend on environmental conditions, herbivore identity and herbivore abundance. As anthropogenic impacts continue to drive large declines in wild herbivores, understanding the context dependence of herbivore impacts on plant communities becomes increasingly important. 2. Exclosure experiments are frequently used to assess how ecosystems reorganize in the face of large wild herbivore defaunation. Yet in many landscapes, declines in large wildlife are often accompanied by other anthropogenic activities, especially land conversion to livestock production. In such cases, exclosure experiments may not reflect typical outcomes of human-driven extirpations of wild herbivores. 3. Here, we examine how plant community responses to changes in the identity and abundance of large herbivores interact with abiotic factors (rainfall and soil properties). We also explore how effects of wild herbivores on plant communities differ between large-scale herbivore exclosures and landscape sites where anthropogenic activity has caused wildlife declines, often accompanied by livestock increases. 4. Abiotic context modulated the responses of plant communities to herbivore declines with stronger effect sizes in lower-productivity environments. Also, shifts in plant community structure, composition and species richness following wildlife declines differed considerably between exclosure experiments and landscape sites in which wild herbivores had declined and were often replaced by livestock. Plant communities in low wildlife landscape sites were distinct in both composition and physical structure from both exclosure and control sites in experiments. The power of environmental (soil and rainfall) gradients in influencing plant response to herbivores was also greatly dampened or absent in the landscape sites. One likely explanation for these observed differences is the compensatory effect of livestock associated with the depression or extirpation of wildlife. 5.Synthesis. Our results emphasize the importance of abiotic environmental heterogeneity in modulating the effects of mammalian herbivory on plant communities and the importance of such covariation in understanding effects of wild herbivore declines. They also suggest caution when extrapolating results from exclosure experiments to predict the consequences of defaunation as it proceeds in the Anthropocene.
View details for DOI 10.1111/1365-2745.12096
View details for Web of Science ID 000320938100020
View details for PubMedCentralID PMC3758959
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Genetic basis of pathogen community structure for foundation tree species in a common garden and in the wild
JOURNAL OF ECOLOGY
2013; 101 (4): 867-877
View details for DOI 10.1111/1365-2745.12112
View details for Web of Science ID 000320938100004
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Ecological and evolutionary consequences of living in a defaunated world
BIOLOGICAL CONSERVATION
2013; 163: 1-6
View details for DOI 10.1016/j.biocon.2013.04.020
View details for Web of Science ID 000321724400001
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Effects of grasses on sapling establishment and the role of transplanted saplings on the light environment of pastures: implications for tropical forest restoration
APPLIED VEGETATION SCIENCE
2013; 16 (2): 296-304
View details for DOI 10.1111/j.1654-109X.2012.01217.x
View details for Web of Science ID 000315690500014
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The roles of productivity and ecosystem size in determining food chain length in tropical terrestrial ecosystems
ECOLOGY
2013; 94 (3): 692-701
Abstract
Many different drivers, including productivity, ecosystem size, and disturbance, have been considered to explain natural variation in the length of food chains. Much remains unknown about the role of these various drivers in determining food chain length, and particularly about the mechanisms by which they may operate in terrestrial ecosystems, which have quite different ecological constraints than aquatic environments, where most food chain length studies have been thus far conducted. In this study, we tested the relative importance of ecosystem size and productivity in influencing food chain length in a terrestrial setting. We determined that (1) there is no effect of ecosystem size or productive space on food chain length; (2) rather, food chain length increases strongly and linearly with productivity; and (3) the observed changes in food chain length are likely achieved through a combination of changes in predator size, predator behavior, and consumer diversity along gradients in productivity. These results lend new insight into the mechanisms by which productivity can drive changes in food chain length, point to potential for systematic differences in the drivers of food web structure between terrestrial and aquatic systems, and challenge us to consider how ecological context may control the drivers that shape food chain length.
View details for Web of Science ID 000317044300016
View details for PubMedID 23687895
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Plant defense, herbivory, and the growth of Cordia alliodora trees and their symbiotic Azteca ant colonies
OECOLOGIA
2012; 170 (3): 677-685
Abstract
The effects of herbivory on plant fitness are integrated over a plant's lifetime, mediated by ontogenetic changes in plant defense, tolerance, and herbivore pressure. In symbiotic ant-plant mutualisms, plants provide nesting space and food for ants, and ants defend plants against herbivores. The benefit to the plant of sustaining the growth of symbiotic ant colonies depends on whether defense by the growing ant colony outpaces the plant's growth in defendable area and associated herbivore pressure. These relationships were investigated in the symbiotic mutualism between Cordia alliodora trees and Azteca pittieri ants in a Mexican tropical dry forest. As ant colonies grew, worker production remained constant relative to ant-colony size. As trees grew, leaf production increased relative to tree size. Moreover, larger trees hosted lower densities of ants, suggesting that ant-colony growth did not keep pace with tree growth. On leaves with ants experimentally excluded, herbivory per unit leaf area increased exponentially with tree size, indicating that larger trees experienced higher herbivore pressure per leaf area than smaller trees. Even with ant defense, herbivory increased with tree size. Therefore, although larger trees had larger ant colonies, ant density was lower in larger trees, and the ant colonies did not provide sufficient defense to compensate for the higher herbivore pressure in larger trees. These results suggest that in this system the tree can decrease herbivory by promoting ant-colony growth, i.e., sustaining space and food investment in ants, as long as the tree continues to grow.
View details for DOI 10.1007/s00442-012-2340-x
View details for Web of Science ID 000309866200009
View details for PubMedID 22562422
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Averting biodiversity collapse in tropical forest protected areas
NATURE
2012; 489 (7415): 290-?
Abstract
The rapid disruption of tropical forests probably imperils global biodiversity more than any other contemporary phenomenon. With deforestation advancing quickly, protected areas are increasingly becoming final refuges for threatened species and natural ecosystem processes. However, many protected areas in the tropics are themselves vulnerable to human encroachment and other environmental stresses. As pressures mount, it is vital to know whether existing reserves can sustain their biodiversity. A critical constraint in addressing this question has been that data describing a broad array of biodiversity groups have been unavailable for a sufficiently large and representative sample of reserves. Here we present a uniquely comprehensive data set on changes over the past 20 to 30 years in 31 functional groups of species and 21 potential drivers of environmental change, for 60 protected areas stratified across the world’s major tropical regions. Our analysis reveals great variation in reserve ‘health’: about half of all reserves have been effective or performed passably, but the rest are experiencing an erosion of biodiversity that is often alarmingly widespread taxonomically and functionally. Habitat disruption, hunting and forest-product exploitation were the strongest predictors of declining reserve health. Crucially, environmental changes immediately outside reserves seemed nearly as important as those inside in determining their ecological fate, with changes inside reserves strongly mirroring those occurring around them. These findings suggest that tropical protected areas are often intimately linked ecologically to their surrounding habitats, and that a failure to stem broad-scale loss and degradation of such habitats could sharply increase the likelihood of serious biodiversity declines.
View details for DOI 10.1038/nature11318
View details for Web of Science ID 000308635900041
View details for PubMedID 22832582
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Effects of Spatial Subsidies and Habitat Structure on the Foraging Ecology and Size of Geckos
PLOS ONE
2012; 7 (8)
Abstract
While it is well established that ecosystem subsidies--the addition of energy, nutrients, or materials across ecosystem boundaries--can affect consumer abundance, there is less information available on how subsidy levels may affect consumer diet, body condition, trophic position, and resource partitioning among consumer species. There is also little information on whether changes in vegetation structure commonly associated with spatial variation in subsidies may play an important role in driving consumer responses to subsidies. To address these knowledge gaps, we studied changes in abundance, diet, trophic position, size, and body condition of two congeneric gecko species (Lepidodactylus spp.) that coexist in palm dominated and native (hereafter dicot dominated) forests across the Central Pacific. These forests differ strongly both in the amount of marine subsidies that they receive from seabird guano and carcasses, and in the physical structure of the habitat. Contrary to other studies, we found that subsidy level had no impact on the abundance of either gecko species; it also did not have any apparent effects on resource partitioning between species. However, it did affect body size, dietary composition, and trophic position of both species. Geckos in subsidized, dicot forests were larger, had higher body condition and more diverse diets, and occupied a much higher trophic position than geckos found in palm dominated, low subsidy level forests. Both direct variation in subsidy levels and associated changes in habitat structure appear to play a role in driving these responses. These results suggest that variation in subsidy levels may drive important behavioral responses in predators, even when their numerical response is limited. Strong changes in trophic position of consumers also suggest that subsidies may drive increasingly complex food webs, with longer overall food chain length.
View details for DOI 10.1371/journal.pone.0041364
View details for PubMedID 22899995
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Diversification and phylogeographic structure in widespread Azteca plant-ants from the northern Neotropics
MOLECULAR ECOLOGY
2012; 21 (14): 3576-3592
Abstract
The Neotropical myrmecophytic tree Cordia alliodora hosts symbiotic Azteca ants in most of its widespread range. The taxonomy of the genus Azteca is notoriously difficult, which has frequently obscured species identity in ecological studies. We used sequence data from one mitochondrial and four nuclear loci to infer phylogenetic relationships, patterns of geographic distribution, and timing of diversification for 182 colonies of five C. alliodora-dwelling Azteca species from Mexico to Colombia. All morphological species were recovered as monophyletic, but we identified at least five distinct genetic lineages within the most abundant and specialized species, Azteca pittieri. Mitochondrial and nuclear data were concordant at the species level, but not within species. Divergence time analyses estimated that C. alliodora-dwelling Azteca shared a common ancestor approximately 10-22million years ago, prior to the proposed arrival of the host tree in Middle America. Diversification in A. pittieri occurred in the Pleistocene and was not correlated with geographic distance, which suggests limited historical gene flow among geographically restricted populations. This contrasts with the previously reported lack of phylogeographic structure at this spatial scale in the host tree. Climatic niches, and particularly precipitation-related variables, did not overlap between the sites occupied by northern and southern lineages of A. pittieri. Together, these results suggest that restricted gene flow among ant populations may facilitate local adaptation to environmental heterogeneity. Differences in population structure between the ants and their host trees may profoundly affect the evolutionary dynamics of this widespread ant-plant mutualism.
View details for DOI 10.1111/j.1365-294X.2012.05618.x
View details for Web of Science ID 000306087100017
View details for PubMedID 22646059
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From wing to wing: the persistence of long ecological interaction chains in less-disturbed ecosystems
SCIENTIFIC REPORTS
2012; 2
Abstract
Human impact on biodiversity usually is measured by reduction in species abundance or richness. Just as important, but much more difficult to discern, is the anthropogenic elimination of ecological interactions. Here we report on the persistence of a long ecological interaction chain linking diverse food webs and habitats in the near-pristine portions of a remote Pacific atoll. Using biogeochemical assays, animal tracking, and field surveys we show that seabirds roosting on native trees fertilize soils, increasing coastal nutrients and the abundance of plankton, thus attracting manta rays to native forest coastlines. Partnered observations conducted in regions of this atoll where native trees have been replaced by human propagated palms reveal that this complex interaction chain linking trees to mantas readily breaks down. Taken together these findings provide a compelling example of how anthropogenic disturbance may be contributing to widespread reductions in ecological interaction chain length, thereby isolating and simplifying ecosystems.
View details for DOI 10.1038/srep00409
View details for Web of Science ID 000304393800001
View details for PubMedID 22624091
View details for PubMedCentralID PMC3354671
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The effect of land use change and ecotourism on biodiversity: a case study of Manuel Antonio, Costa Rica, from 1985 to 2008
LANDSCAPE ECOLOGY
2012; 27 (5): 731-744
View details for DOI 10.1007/s10980-012-9722-7
View details for Web of Science ID 000303056100009
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Consequences of Fragmentation of Tropical Moist Forest for Birds and Their Role in Predation of Herbivorous Insects
BIOTROPICA
2012; 44 (2): 228-236
View details for DOI 10.1111/j.1744-7429.2011.00795.x
View details for Web of Science ID 000300941200012
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Intersexual comparison of DNA content by flow cytometry, and chromosome number in four dioecious Chamaedorea palms from Mexico
CARYOLOGIA
2012; 65 (4): 263-270
View details for DOI 10.1080/00087114.2012.752910
View details for Web of Science ID 000314971800003
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HYBRIDIZATION AMONG DOMINANT TREE SPECIES CORRELATES POSITIVELY WITH UNDERSTORY PLANT DIVERSITY
AMERICAN JOURNAL OF BOTANY
2011; 98 (10): 1623-1632
Abstract
Elucidating the factors that determine the abundance and distribution of species remains a central goal of ecology. It is well recognized that genetic differences among individual species can affect the distribution and species interactions of dependent taxa, but the ecological effects of genetic differences on taxa of the same trophic level remain much less understood. Our goal was to test the hypothesis that differences between related overstory tree species and their hybrids can influence the understory plant community in wild settings.We conducted vegetation surveys in a riparian community with the overstory dominated by Populus fremontii, P. angustifolia, and their natural hybrids (referred to as cross types) along the Weber River in north central Utah, USA. Understory diversity and community composition, as well as edaphic properties, were compared under individual trees.Diversity metrics differ under the three different tree cross types such that a greater species richness, diversity, and cover of understory plants exist under the hybrids compared with either of the parental taxa (30-54%, 40-48%, and 35-74% greater, respectively). The community composition of the understory also varied by cross type, whereby additional understory plant species cluster with hybrids, not with parental species.Genetic composition dictated by hybridization in the overstory can play a role in structuring the associated understory plants in natural communities-where a hybridized overstory correlates with a species-rich understory-and thus can have cascading effects on community members of the same trophic level. The underlying mechanism requires further investigation.
View details for DOI 10.3732/ajb.1100137
View details for Web of Science ID 000295888800018
View details for PubMedID 21960550
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Jaguars, tapirs, and lessons in conservation ecology
FRONTIERS IN ECOLOGY AND THE ENVIRONMENT
2011; 9 (8): 470-471
View details for DOI 10.1890/1540-9295-9.8.470
View details for Web of Science ID 000295910900022
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Analysis of a hyper-diverse seed dispersal network: modularity and underlying mechanisms
ECOLOGY LETTERS
2011; 14 (8): 773-781
Abstract
Mutualistic interactions involving pollination and ant-plant mutualistic networks typically feature tightly linked species grouped in modules. However, such modularity is infrequent in seed dispersal networks, presumably because research on those networks predominantly includes a single taxonomic animal group (e.g. birds). Herein, for the first time, we examine the pattern of interaction in a network that includes multiple taxonomic groups of seed dispersers, and the mechanisms underlying modularity. We found that the network was nested and modular, with five distinguishable modules. Our examination of the mechanisms underlying such modularity showed that plant and animal trait values were associated with specific modules but phylogenetic effect was limited. Thus, the pattern of interaction in this network is only partially explained by shared evolutionary history. We conclude that the observed modularity emerged by a combination of phylogenetic history and trait convergence of phylogenetically unrelated species, shaped by interactions with particular types of dispersal agents.
View details for DOI 10.1111/j.1461-0248.2011.01639.x
View details for Web of Science ID 000292864400007
View details for PubMedID 21699640
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Differential diameter-size effects of forest management on tree species richness and community structure: implications for conservation
BIODIVERSITY AND CONSERVATION
2011; 20 (7): 1571-1585
View details for DOI 10.1007/s10531-011-0046-8
View details for Web of Science ID 000290726200014
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Distinct Leaf-trait Syndromes of Evergreen and Deciduous Trees in a Seasonally Dry Tropical Forest
BIOTROPICA
2011; 43 (3): 299-308
View details for DOI 10.1111/j.1744-7429.2010.00697.x
View details for Web of Science ID 000289902000005
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A Novel Method to Improve Individual Animal Identification Based on Camera-Trapping Data
JOURNAL OF WILDLIFE MANAGEMENT
2011; 75 (4): 973-979
View details for DOI 10.1002/jwmg.120
View details for Web of Science ID 000291818100025
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DIFFERENTIAL RESPONSES TO GUANO FERTILIZATION AMONG TROPICAL TREE SPECIES WITH VARYING FUNCTIONAL TRAITS
AMERICAN JOURNAL OF BOTANY
2011; 98 (2): 207-214
Abstract
Seabirds often cause significant changes to soil properties, and seabird-dominated systems often host unique plant communities. This study experimentally (1) examined species-specific responses to seabird guano gradients, (2) considered the role that differential functional traits among species play in altering plant response to guano, and (3) investigated the implications of seabird guano on range-expanding species.Using a greenhouse fertilization experiment, we examined how guano fertilization affects the growth and functional traits of four tree species dominant in the Pacific Islands: Cocos nucifera, Pisonia grandis, Scaevola sericea, and Tournefortia argentea. In these systems, seabirds are frequently found in association with three of these four species; the remaining species, C. nucifera, is a recently proliferating species commonly found in the region but rarely associated with seabirds.We determined that responses to guano addition differed significantly between species in ways that were consistent with predictions based on differing functional traits among species. Notably, we demonstrated that C. nucifera showed no growth responses to guano additions, whereas all seabird-associated plants showed strong responses.These results provide experimental evidence of differential species response to guano additions, suggesting that differences in species functional traits may contribute to changes in plant communities in seabird-dominated areas, with seabird-associated species garnering performance advantages in these high-nutrient environments. Among these species, results also suggest that C. nucifera may have a competitive advantage in low-nutrient environments, providing an unusual example of how a range-expanding plant species can profit from low-nutrient environments.
View details for DOI 10.3732/ajb.1000159
View details for Web of Science ID 000286884500015
View details for PubMedID 21613110
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Indirect benefits of symbiotic coccoids for an ant-defended myrmecophytic tree
ECOLOGY
2011; 92 (1): 37-46
Abstract
The net benefits of mutualism depend directly on the costs and effectiveness of mutualistic services and indirectly on the interactions that affect those services. We examined interactions among Cordia alliodora myrmecophytic trees, their symbiotic ants Azteca pittieri, coccoid hemipterans, and foliar herbivores in two Neotropical dry forests. The tree makes two investments in symbiotic ants: it supplies nesting space, as domatia, and it provides phloem to coccoids, which then produce honeydew that is consumed by ants. Although higher densities of coccoids should have higher direct costs for trees, we asked whether higher densities of coccoids can also have higher indirect benefits for trees by increasing the effectiveness of ant defense against foliar herbivores. We found that trees benefited from ant defense against herbivores. Ants defended trees effectively only when colonies reached high densities within trees, and ant and coccoid densities within trees were strongly positively correlated. The benefits of reduced foliar herbivory by larger ant colonies were therefore indirectly controlled by the number of coccoids. Coccoid honeydew supply also affected per capita ant aggression against tree herbivores. Ants experimentally fed a carbohydrate-rich diet, analogous to sugar obtained from coccoids, were more aggressive against caterpillars per capita than ants fed a carbohydrate-poor diet. Ant defense was more effective on more valuable and vulnerable young leaves than on older leaves. Young domatia, associated with young leaves, contained higher coccoid densities than older domatia, which suggests that coccoids may also drive spatially favorable ant defense of the tree. If higher investments by one mutualistic partner are tied to higher benefits received from the other, there may be positive feedback between partners that will stabilize the mutualism. These results suggest that higher investment by trees in coccoids leads to more effective defense by ants against the tree's foliar herbivores.
View details for Web of Science ID 000289552200006
View details for PubMedID 21560674
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Influence of Tree Ontogeny on Plant-Herbivore Interactions
SIZE- AND AGE-RELATED CHANGES IN TREE STRUCTURE AND FUNCTION
2011; 4: 193-214
View details for DOI 10.1007/978-94-007-1242-3_7
View details for Web of Science ID 000293799600007
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Effects of forest fragmentation on assemblages of pollinators and floral visitors to male- and female-phase inflorescences of Astrocaryum mexicanum (Arecaceae) in a Mexican rain forest
JOURNAL OF TROPICAL ECOLOGY
2011; 27: 25-33
View details for DOI 10.1017/S0266467410000556
View details for Web of Science ID 000285722500003
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The coconut palm, Cocos nucifera, impacts forest composition and soil characteristics at Palmyra Atoll, Central Pacific
JOURNAL OF VEGETATION SCIENCE
2010; 21 (6): 1058-1068
View details for DOI 10.1111/j.1654-1103.2010.01219.x
View details for Web of Science ID 000283600000006
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Plant stages with biotic, indirect defences are more palatable and suffer less herbivory than their undefended counterparts
BIOLOGICAL JOURNAL OF THE LINNEAN SOCIETY
2010; 101 (3): 536-543
View details for DOI 10.1111/j.1095-8312.2010.01521.x
View details for Web of Science ID 000283081700003
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IN MEMORY OF PAUL S. MARTIN (August 22nd 1928 - September 13th 2010), has works published, American geoscientist
CIENCIAUAT
2010; 5 (2): 8
View details for Web of Science ID 000215585500001
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Delineation of biogeomorphic land units across a tropical natural and humanized terrain in Los Tuxtlas, Veracruz, Mexico
GEOMORPHOLOGY
2010; 121 (3-4): 245-256
View details for DOI 10.1016/j.geomorph.2010.04.019
View details for Web of Science ID 000280915400009
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Experimental defoliation affects male but not female reproductive performance of the tropical monoecious plant Croton suberosus (Euphorbiaceae)
ANNALS OF BOTANY
2010; 106 (2): 359-369
Abstract
Monoecious plants have the capacity to allocate resources separately to male and female functions more easily than hermaphrodites. This can be advantageous against environmental stresses such as leaf herbivory. However, studies showing effects of herbivory on male and female functions and on the interaction with the plant's pollinators are limited, particularly in tropical plants. Here, the effects of experimental defoliation were examined in the monoecious shrub Croton suberosus (Euphorbiaceae), a wasp-pollinated species from a Mexican tropical dry forest.Three defoliation treatments were applied: 0 % (control), 25 % (low) or 75 % (high) of plant leaf area removed. Vegetative (production of new leaves) and reproductive (pistillate and staminate flower production, pollen viability, nectar production, fruit set, and seed set) performance variables, and the abundance and activity of floral visitors were examined.Defoliated plants overcompensated for tissue loss by producing more new leaves than control plants. Production of staminate flowers gradually decreased with increasing defoliation and the floral sex ratio (staminate : pistillate flowers) was drastically reduced in high-defoliation plants. In contrast, female reproductive performance (pistillate flower production, fruit set and seed set) and pollinator visitation and abundance were not impacted by defoliation.The asymmetrical effects of defoliation on male and female traits of C. suberosus may be due to the temporal and spatial flexibility in the allocation of resources deployed by monoecious plants. We posit that this helps to maintain the plant's pollination success in the face of leaf herbivory stress.
View details for DOI 10.1093/aob/mcq117
View details for Web of Science ID 000280264400012
View details for PubMedID 20519239
View details for PubMedCentralID PMC2908170
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K-12 science education and "broader impacts"
FRONTIERS IN ECOLOGY AND THE ENVIRONMENT
2010; 8 (4): 217-218
View details for Web of Science ID 000277450500022
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A REASSESSMENT OF THE FUNCTION OF FLORAL NECTAR IN CROTON SUBEROSUS (EUPHORBIACEAE): A REWARD FOR PLANT DEFENDERS AND POLLINATORS
AMERICAN JOURNAL OF BOTANY
2010; 97 (4): 672-679
Abstract
Typically, plant-pollinator interactions are recognized as mutualistic relationships. Flower visitors, however, can potentially play multiple roles. The floral nectar in Croton suberosus has been proposed to operate as a reward for predators, especially the wasp Polistes instabilis (Vespidae), which kills herbivorous insects, while the plant has been thought to be mainly wind-pollinated. In this study, we reassessed the pollination mode of C. suberosus and the possible role of its flower visitors. Pollinator exclusion experiments demonstrated that C. suberosus should be considered a strictly entomophilous species. Inflorescences of C. suberosus were visited by a diverse entomofauna involving 28 taxa belonging to six orders; however, wasps and bees were the only visitors that carried C. suberosus pollen. The visitation rate of wasps was approximately four times that of bees. This observation, combined with the fact that the small size of bees makes effective contact of their bodies with the stigma difficult, strongly suggests that large wasps are responsible for most of the effective pollination of C. suberosus. Among the wasp visitors, P. instabilis seems to be one of the most important. These findings expose an unusual plant-insect interaction, in which the plant provides nectar and wasps pollinate and defend the plant.
View details for DOI 10.3732/ajb.0900259
View details for Web of Science ID 000276045500014
View details for PubMedID 21622429
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Sex-Related Differences in Reproductive Allocation, Growth, Defense and Herbivory in Three Dioecious Neotropical Palms
PLOS ONE
2010; 5 (3)
Abstract
Frequently, in dioecious plants, female plants allocate more resources to reproduction than male plants. Therefore it is expected that asymmetrical allocation to reproduction may lead to a reproduction-growth tradeoff, whereby female plants grow less than male plants, but invest more in defenses and thus experience lower herbivory than male plants.We tested these expectations by comparing resource allocation to reproduction, growth and defense and its consequences on herbivory in three sympatric dioecious Chamaedorea palms (C. alternans, C. pinnatifrons and C. ernesti-augusti) using a pair-wise design (replicated male/female neighboring plants) in a Mexican tropical rain forest. Our findings support the predictions. Biomass allocation to reproduction in C. pinnatifrons was 3-times higher in female than male plants, consistent with what is known in C. alternans and C. ernesti-augusti. Growth (height and leaf production rate and biomass production) was higher in male plants of all three species. Female plants of the three species had traits that suggest greater investment in defense, as they had 4-16% tougher leaves, and 8-18% higher total phenolic compounds concentration. Accordingly, female plants sustained 53-78% lower standing herbivory and 49-87% lower herbivory rates than male plants.Our results suggests that resource allocation to reproduction in the studied palms is more costly to female plants and this leads to predictable intersexual differences in growth, defense and herbivory. We conclude that resource allocation to reproduction in plants can have important consequences that influence their interaction with herbivores. Since herbivory is recognized as an important selective force in plants, these results are of significance to our understanding of plant defense evolution.
View details for DOI 10.1371/journal.pone.0009824
View details for Web of Science ID 000275894400024
View details for PubMedID 20352113
View details for PubMedCentralID PMC2843723
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Importance of the lilac-crowned parrot in pre-dispersal seed predation of Astronium graveolens in a Mexican tropical dry forest
JOURNAL OF TROPICAL ECOLOGY
2010; 26: 227-236
View details for DOI 10.1017/S0266467409990447
View details for Web of Science ID 000274986000010
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Plants cause ecosystem nutrient depletion via the interruption of bird-derived spatial subsidies
PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA
2010; 107 (5): 2072-2077
Abstract
Plant introductions and subsequent community shifts are known to affect nutrient cycling, but most such studies have focused on nutrient enrichment effects. The nature of plant-driven nutrient depletions and the mechanisms by which these might occur are relatively poorly understood. In this study we demonstrate that the proliferation of the commonly introduced coconut palm, Cocos nucifera, interrupts the flow of allochthonous marine subsidies to terrestrial ecosystems via an indirect effect: impact on birds. Birds avoid nesting or roosting in C. nucifera, thus reducing the critical nutrient inputs they bring from the marine environment. These decreases in marine subsidies then lead to reductions in available soil nutrients, decreases in leaf nutrient quality, diminished leaf palatability, and reduced herbivory. This nutrient depletion pathway contrasts the more typical patterns of nutrient enrichment that follow plant species introductions. Research on the effects of spatial subsidy disruptions on ecosystems has not yet examined interruptions driven by changes within the recipient community, such as plant community shifts. The ubiquity of coconut palm introductions across the tropics and subtropics makes these observations particularly noteworthy. Equally important, the case of C. nucifera provides a strong demonstration of how plant community changes can dramatically impact the supply of allochthonous nutrients and thereby reshape energy flow in ecosystems.
View details for DOI 10.1073/pnas.0914169107
View details for Web of Science ID 000274296300049
View details for PubMedID 20133852
View details for PubMedCentralID PMC2836700
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Insect herbivory declines with forest fragmentation and covaries with plant regeneration mode: evidence from a Mexican tropical rain forest
OIKOS
2010; 119 (2): 317-325
View details for DOI 10.1111/j.1600-0706.2009.17614.x
View details for Web of Science ID 000275557500014
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Niche partitioning among and within sympatric tropical seabirds revealed by stable isotope analysis
MARINE ECOLOGY PROGRESS SERIES
2010; 416: 285-294
View details for DOI 10.3354/meps08756
View details for Web of Science ID 000283446400023
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Resource partitioning by species but not sex in sympatric boobies in the central Pacific Ocean
MARINE ECOLOGY PROGRESS SERIES
2010; 403: 291-301
View details for DOI 10.3354/meps08478
View details for Web of Science ID 000276799000024
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Prevalence of Tree Regeneration by Sprouting and Seeding Along a Rainfall Gradient in Hawai'i
BIOTROPICA
2010; 42 (1): 80-86
View details for DOI 10.1111/j.1744-7429.2009.00540.x
View details for Web of Science ID 000273301100012
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Indirect effects of timber extraction on plant recruitment and diversity via reductions in abundance of frugivorous spider monkeys
JOURNAL OF TROPICAL ECOLOGY
2010; 26: 45-52
View details for DOI 10.1017/S0266467409990307
View details for Web of Science ID 000273149300005
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SEED REMOVAL, HERBIVORIA AND RECRUITMENT OF BROSIMUM ALICASTRUM PLANTS (MORACEAE) IN CONTRASTING SITES WITH FOREST MANAGEMENT, QUINTANA ROO, MEXICO
BOLETIN DE LA SOCIEDAD BOTANICA DE MEXICO
2009; 85: 51-58
View details for Web of Science ID 000273192600005
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SEED TOLERANCE TO PREDATION: EVIDENCE FROM THE TOXIC SEEDS OF THE BUCKEYE TREE (AESCULUS CALIFORNICA; SAPINDACEAE)
AMERICAN JOURNAL OF BOTANY
2009; 96 (7): 1255-1261
Abstract
Tolerance, the capacity of plants to withstand attack by animals, as opposed to resistance, has been poorly examined in the context of seed predation. We investigated the role that the seed mass of the large-seeded endemic tree Aesculus californica plays as a tolerance trait to rodent attack by comparing, under greenhouse conditions, patterns of germination, and subsequent seedling growth, of seeds with a wide range of natural damage. Germination percentage was reduced by 50% and time to germination by 64% in attacked compared to intact seeds, and germination probability was negatively correlated with damage. Seedlings that emerged from intact seeds were taller and bore more leaves than those from damaged seeds. This species' large seed mass favors tolerance to damage because heavily damaged seeds are able to germinate and produce seedlings. This finding is significant given that seeds of this species are known to contain chemical compounds toxic to vertebrates, a resistance trait. We posit that this combination of tolerance and resistance traits might be a particularly effective antipredation strategy when seeds are exposed to a variety of vertebrate predators.
View details for DOI 10.3732/ajb.0800297
View details for Web of Science ID 000267870800005
View details for PubMedID 21628274
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Morphological variation in the flowers of Jacaratia mexicana A. DC. (Caricaceae), a subdioecious tree
PLANT BIOLOGY
2009; 11 (3): 417-424
Abstract
The Caricaceae is a small family of tropical trees and herbs in which most species are dioecious. In the present study, we extend our previous work on dioecy in the Caricaceae, characterising the morphological variation in sexual expression in flowers of the dioecious tree Jacaratia mexicana. We found that, in J. mexicana, female plants produce only pistillate flowers, while male plants are sexually variable and can bear three different types of flowers: staminate, pistillate and perfect. To characterise the distinct types of flowers, we measured 26 morphological variables. Our results indicate that: (i) pistillate flowers from male trees carry healthy-looking ovules and are morphologically similar, although smaller than, pistillate flowers on female plants; (ii) staminate flowers have a rudimentary, non-functional pistil and are the only flowers capable of producing nectar; and (iii) perfect flowers produce healthy-looking ovules and pollen, but have smaller ovaries than pistillate flowers and fewer anthers than staminate flowers, and do not produce nectar. The restriction of sexual variation to male trees is consistent with the evolutionary path of dioecy from hermaphrodite ancestors through the initial invasion of male-sterile plants and a subsequent gradual reduction in female fertility in cosexual individuals (gynodioecy pathway), but further work is needed to confirm this hypothesis.
View details for DOI 10.1111/j.1438-8677.2008.00154.x
View details for Web of Science ID 000265015300015
View details for PubMedID 19470112
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2008 ATBC Honorary Fellows Prof. Ernesto Medina
BIOTROPICA
2009; 41 (1): 137-138
View details for Web of Science ID 000261961100019
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Effects of fragmentation on pollinator abundance and fruit set of an abundant understory palm in a Mexican tropical forest
BIOLOGICAL CONSERVATION
2008; 141 (2): 375-384
View details for DOI 10.1016/j.biocon.2007.09.014
View details for Web of Science ID 000254599900005
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Effects of Amazonian forest fragmentation on the interaction between plants, insect herbivores, and their natural enemies
JOURNAL OF TROPICAL ECOLOGY
2008; 24: 57-64
View details for DOI 10.1017/S0266467407004592
View details for Web of Science ID 000252822200007
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Seed-size variation determines interspecific differential predation by mammals in a neotropical rain forest
OIKOS
2007; 116 (11): 1841-1852
View details for DOI 10.1111/j.2007.0030-1299.15878.x
View details for Web of Science ID 000251278700007
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The plight of large animals in tropical forests and the consequences for plant regeneration
Annual Meeting of the Association-for-Tropical-Biology-and-Conservation
WILEY-BLACKWELL. 2007: 289–91
View details for DOI 10.1111/j.1744-7429.2007.00293.x
View details for Web of Science ID 000245939300001
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Size-related differential seed predation in a heavily defaunated neotropical rain forest
Annual Meeting of the Association-for-Tropical-Biology-and-Conservation
WILEY-BLACKWELL. 2007: 355–62
View details for DOI 10.1111/j.1744-7429.2007.00274.x
View details for Web of Science ID 000245939300008
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Ontogenetic switches from plant resistance to tolerance: minimizing costs with age?
ECOLOGY LETTERS
2007; 10 (3): 177-187
Abstract
Changes in herbivory and resource availability during a plant's development should promote ontogenetic shifts in resistance and tolerance, if the costs and benefits of these basic strategies also change as plants develop. We proposed and tested a general model to detect the expression of ontogenetic tradeoffs for these two alternative anti-herbivory strategies in Raphanus sativus. We found that ontogenetic trajectories occur in both resistance and tolerance but in opposite directions. The juvenile stage was more resistant but less tolerant than the reproductive stage. The ontogenetic switch from resistance to tolerance was consistent with the greater vulnerability of young plants to leaf damage and with the costs of resistance and tolerance found at each stage. We posit that the ontogenetic perspective presented here will be helpful in resolving the current debate on the existence and detection of a general resistance-tolerance tradeoff.
View details for DOI 10.1111/j.1461-0248.2006.01012.x
View details for Web of Science ID 000244227800003
View details for PubMedID 17305801
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Floristic diversity of sabal palmetto woodland: an endemic and endangered vegetation type from Mexico
BIODIVERSITY AND CONSERVATION
2007; 16 (3): 807-825
View details for DOI 10.1007/s10531-005-6228-5
View details for Web of Science ID 000244684700015
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Variation in sexual expression in Jacaratia mexicana (Caricaceae) in southern Mexico: Frequency and relative seed performance of fruit-producing males
BIOTROPICA
2007; 39 (1): 79-86
View details for DOI 10.1111/j.1744-7429.2006.00230.x
View details for Web of Science ID 000243294500011
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Biased seed rain in forest edges: Evidence from the Brazilian Atlantic forest
BIOLOGICAL CONSERVATION
2006; 132 (1): 50-60
View details for DOI 10.1016/j.biocon.2006.03.015
View details for Web of Science ID 000240273500006
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The evolution of ecology in Mexico: facing challenges and preparing for the future
FRONTIERS IN ECOLOGY AND THE ENVIRONMENT
2006; 4 (5): 259-267
View details for Web of Science ID 000238085500025
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An endangered oasis of aquatic microbial biodiversity in the Chihuahuan desert
PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA
2006; 103 (17): 6565-6570
Abstract
The Cuatro Cienegas basin in the Chihuahuan desert is a system of springs, streams, and pools. These ecosystems support >70 endemic species and abundant living stromatolites and other microbial communities, representing a desert oasis of high biodiversity. Here, we combine data from molecular microbiology and geology to document the microbial biodiversity of this unique environment. Ten water samples from locations within the Cuatro Cienegas basin and two neighboring valleys as well as three samples of wet sediments were analyzed. The phylogeny of prokaryotic populations in the samples was determined by characterizing cultured organisms and by PCR amplification and sequencing of 16S rRNA genes from total community DNA. The composition of microbial communities was also assessed by determining profiles of terminal restriction site polymorphisms of 16S rRNA genes in total community DNA. There were 250 different phylotypes among the 350 cultivated strains. Ninety-eight partial 16S rRNA gene sequences were obtained and classified. The clones represented 38 unique phylotypes from ten major lineages of Bacteria and one of Archaea. Unexpectedly, 50% of the phylotypes were most closely related to marine taxa, even though these environments have not been in contact with the ocean for tens of millions of years. Furthermore, terminal restriction site polymorphism profiles and geological data suggest that the aquatic ecosystems of Cuatro Cienegas are hydrologically interconnected with adjacent valleys recently targeted for agricultural intensification. The findings underscore the conservation value of desert aquatic ecosystems and the urgent need for study and preservation of freshwater microbial communities.
View details for DOI 10.1073/pnas.0601434103
View details for Web of Science ID 000237151000028
View details for PubMedID 16618921
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Simulated seed predation reveals a variety of germination responses of neotropical rain forest species
AMERICAN JOURNAL OF BOTANY
2006; 93 (3): 369-376
Abstract
Seed predation, an omnipresent phenomenon in tropical rain forests, is an important determinant of plant recruitment and forest regeneration. Although seed predation destroys large amounts of the seed crop of numerous tropical species, in many cases individual seed damage is only partial. The extent to which partial seed predation affects the recruitment of new individuals in the population depends on the type and magnitude of alteration of the germination behavior of the damaged seeds. We analyzed the germination dynamics of 11 tropical woody species subject to increasing levels of simulated seed predation (0-10% seed mass removal). Germination response to seed damage varied considerably among species but could be grouped into four distinct types: (1) complete inability to germinate under damage ≥1%, (2) no effect on germination dynamics, (3) reduced germination with increasing damage, and (4) reduced final germination but faster germination with increasing damage. We conclude that partial seed predation is often nonlethal and argue that different responses to predation may represent different proximal mechanisms for coping with partial damage, with potential to shape, in the long run, morphological and physiological adaptations in tropical, large-seeded species.
View details for Web of Science ID 000235986100006
View details for PubMedID 21646197
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Biodiversity science evolves
SCIENCE
2005; 310 (5750): 943
View details for DOI 10.1126/science.1119958
View details for Web of Science ID 000233343400001
View details for PubMedID 16284147
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A quantitative analysis of forest fragmentation in Los Tuxtlas, southeast Mexico: patterns and implications for conservation
REVISTA CHILENA DE HISTORIA NATURAL
2005; 78 (3): 451-467
View details for Web of Science ID 000232544500008
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Diversitas and the challenge of Latin American biodiversity conservation
INTERCIENCIA
2005; 30 (8): 450-450
View details for Web of Science ID 000231542300001
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Post-classification digital change detection analysis of a temperate forest in the southwest basin of Mexico City, in a 16-year span
3rd International Workshop on the Analysis of Multi-Temporal Remote Sensing Images
IEEE. 2005: 81–84
View details for Web of Science ID 000231288600018
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Myrmecophily: Plants with their own army
INTERCIENCIA
2004; 29 (12): 673-?
View details for Web of Science ID 000226353300004
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Diversity of gall-inducing insects in a Mexican tropical dry forest: the importance of plant species richness, life-forms, host plant age and plant density
JOURNAL OF ECOLOGY
2004; 92 (4): 707-716
View details for Web of Science ID 000222869400014
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Intraspecific variation in growth, defense and herbivory in Dialium guianense (Caesalpiniaceae) mediated by edaphic heterogeneity
PLANT ECOLOGY
2004; 175 (1): 59-69
View details for Web of Science ID 000226444000005
- Global state of biodiversity and loss Annual Review of Environment and Natural Resources 2003; 28: 137-167
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Global state of biodiversity and loss
ANNUAL REVIEW OF ENVIRONMENT AND RESOURCES
2003; 28: 137-167
View details for DOI 10.1146/annurev.energy.28.050302.105532
View details for Web of Science ID 000220102700005
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Does ontogeny cause changes in the defensive strategies of the myrmecophyte Cecropia peltata?
PLANT ECOLOGY
2003; 169 (1): 35-41
View details for Web of Science ID 000186132100003
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Genetic divergence among Mexican populations of red mangrove (Rhizophora mangle): geographic and historic effects
EVOLUTIONARY ECOLOGY RESEARCH
2002; 4 (7): 1049-1064
View details for Web of Science ID 000178941700008
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The causes of land-use and land-cover change: moving beyond the myths
GLOBAL ENVIRONMENTAL CHANGE-HUMAN AND POLICY DIMENSIONS
2001; 11 (4): 261-269
View details for Web of Science ID 000172796700002
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Biodiversity - Global biodiversity scenarios for the year 2100
SCIENCE
2000; 287 (5459): 1770-1774
Abstract
Scenarios of changes in biodiversity for the year 2100 can now be developed based on scenarios of changes in atmospheric carbon dioxide, climate, vegetation, and land use and the known sensitivity of biodiversity to these changes. This study identified a ranking of the importance of drivers of change, a ranking of the biomes with respect to expected changes, and the major sources of uncertainties. For terrestrial ecosystems, land-use change probably will have the largest effect, followed by climate change, nitrogen deposition, biotic exchange, and elevated carbon dioxide concentration. For freshwater ecosystems, biotic exchange is much more important. Mediterranean climate and grassland ecosystems likely will experience the greatest proportional change in biodiversity because of the substantial influence of all drivers of biodiversity change. Northern temperate ecosystems are estimated to experience the least biodiversity change because major land-use change has already occurred. Plausible changes in biodiversity in other biomes depend on interactions among the causes of biodiversity change. These interactions represent one of the largest uncertainties in projections of future biodiversity change.
View details for Web of Science ID 000085775300030
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Global biodiversity scenarios for the year 2100.
Science
2000; 287 (5459): 1770-1774
Abstract
Scenarios of changes in biodiversity for the year 2100 can now be developed based on scenarios of changes in atmospheric carbon dioxide, climate, vegetation, and land use and the known sensitivity of biodiversity to these changes. This study identified a ranking of the importance of drivers of change, a ranking of the biomes with respect to expected changes, and the major sources of uncertainties. For terrestrial ecosystems, land-use change probably will have the largest effect, followed by climate change, nitrogen deposition, biotic exchange, and elevated carbon dioxide concentration. For freshwater ecosystems, biotic exchange is much more important. Mediterranean climate and grassland ecosystems likely will experience the greatest proportional change in biodiversity because of the substantial influence of all drivers of biodiversity change. Northern temperate ecosystems are estimated to experience the least biodiversity change because major land-use change has already occurred. Plausible changes in biodiversity in other biomes depend on interactions among the causes of biodiversity change. These interactions represent one of the largest uncertainties in projections of future biodiversity change.
View details for PubMedID 10710299
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Deforestation in Lacandonia (southeast Mexico): evidence for the declaration of the northernmost tropical hot-spot
BIODIVERSITY AND CONSERVATION
1999; 8 (12): 1621-1641
View details for Web of Science ID 000084982500003
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Consumption of macro-fungi by invertebrates in a Mexican tropical cloud forest: do fruit body characteristics matter?
JOURNAL OF TROPICAL ECOLOGY
1999; 15: 603-617
View details for Web of Science ID 000083517900004
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Ecological science and the human predicament
SCIENCE
1998; 282 (5390): 879-879
View details for Web of Science ID 000076727300020
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Flower morphometry of Rhizophora mangle (Rhizophoraceae): Geographical variation in Mexican populations
AMERICAN JOURNAL OF BOTANY
1998; 85 (5): 637-643
Abstract
We explored the patterns of intra- and interpopulation variation in flower morphology of the red mangrove, Rhizophora mangle. Twelve populations in Mexico were studied: five from the Gulf of Mexico and the Caribbean Sea, and seven from the Pacific Coast. Six metric floral attributes were measured from a sample of 1370 flowers. Significant differences among populations were found for all six attributes. Because floral attributes were all correlated, scores derived from principal factor analysis were used to describe the variation in flower morphology. Two factors explained essentially all of the variance in flower morphology. Corolla and calyx size had a strong effect on factor 1, while gynoecium size had the higher effect on factor 2. Nested analyses of variance on the scores from both factors revealed significant differences among coasts, among populations within coasts, and among plants within populations. Nonetheless, this variation cannot be explained as a result of clinal variation, as indicated by a series of regression analyses. Cluster analysis (UPGMA) showed that a population from the Pacific coast was clustered together with those of the Atlantic, and the arrangement of populations within each coast showed no evident geographical pattern. We propose that frequent events of extinction and recolonization by a few individuals, followed by selfing, may produce differentiation among populations of red mangrove.
View details for Web of Science ID 000073708300004
View details for PubMedID 21715293
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A rapid method for the assessment of the macromycota. The fungal community of an evergreen cloud forest as an example
CANADIAN JOURNAL OF BOTANY-REVUE CANADIENNE DE BOTANIQUE
1998; 76 (4): 596-601
View details for Web of Science ID 000075420600005
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Mating system consequences on resistance to herbivory and life history traits in Datura stramonium
AMERICAN JOURNAL OF BOTANY
1996; 83 (8): 1041-1049
View details for Web of Science ID A1996VD02500010
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The role of an avian nectar robber and of Hummingbird pollinators in the reproduction of two plant species
FUNCTIONAL ECOLOGY
1996; 10 (1): 119-127
View details for Web of Science ID A1996UF09000013
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WITHIN-YEAR AND AMONG-YEAR VARIATION IN THE LEVELS OF HERBIVORY ON THE FOLIAGE OF TREES FROM A MEXICAN TROPICAL DECIDUOUS FOREST
BIOTROPICA
1995; 27 (1): 78-86
View details for Web of Science ID A1995QT58400009
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RAINFALL AND FLOWERING SYNCHRONY IN A TROPICAL SHRUB - VARIABLE SELECTION ON THE FLOWERING TIME OF ERYTHROXYLUM HAVANENSE
EVOLUTIONARY ECOLOGY
1995; 9 (2): 204-216
View details for Web of Science ID A1995QM67900007
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EFFECTS OF DEFOLIATION ON ERYTHROXYLUM HAVANENSE, A TROPICAL PROLEPTIC SPECIES
ECOLOGY
1994; 75 (7): 1896-1902
View details for Web of Science ID A1994PK12900004
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EVOLUTIONARY ECOLOGY OF DATURA-STRAMONIUM L IN CENTRAL MEXICO - NATURAL-SELECTION FOR RESISTANCE TO HERBIVOROUS INSECTS
EVOLUTION
1994; 48 (2): 423-436
View details for Web of Science ID A1994PQ53900014
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EFFECTS OF DEFOLIATION ON THE SAPLINGS OF A GAP-COLONIZING NEOTROPICAL TREE
JOURNAL OF VEGETATION SCIENCE
1991; 2 (4): 459-464
View details for Web of Science ID A1991GR11600004
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ON THE FUNCTION OF FLORAL NECTAR IN CROTON-SUBEROSUS (EUPHORBIACEAE)
OIKOS
1989; 56 (1): 109-114
View details for Web of Science ID A1989AQ56300012
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LEAF SURVIVAL IN RELATION TO HERBIVORY IN 2 TROPICAL PIONEER SPECIES
OIKOS
1989; 55 (1): 71-74
View details for Web of Science ID A1989AA59600010
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WITHIN-GAP SPATIAL HETEROGENEITY AND SEEDLING PERFORMANCE IN A MEXICAN TROPICAL FOREST
OIKOS
1988; 51 (3): 274-284
View details for Web of Science ID A1988M692300004
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SOME IMPORTANT PROBLEMS IN THE STUDY OF HERBIVORE-PLANT INTERACTIONS IN TROPICAL FORESTS
REVISTA DE BIOLOGIA TROPICAL
1987; 35: 207-211
View details for Web of Science ID A1987Q502100019