My scientific work examines the study of species interactions in tropical ecosystems from Latin America and Africa. Recent research highlights the decline of animal life (“defaunation”), and how this affects ecosystem processes/services. I teach ecology, natural history, and conservation science at undergraduate and postgraduate levels at Stanford, and conducts science education programs with underserved children in the Bay Area and in Mexico. My lab includes undergrads, graduate students, postdocs and visiting scholars from US, Latin America and Spain. I have coauthored the new Framework for K-12 Science Education.

Academic Appointments

Administrative Appointments

  • Director, Center for Latin American Studies (2010 - 2016)
  • Co-Director, INOGO Program of the Woods Institute for the Environment (2011 - Present)

Honors & Awards

  • Pew Scholar in Conservation, The Pew Charitable Trust (1992)
  • Outstanding Service Award: Teaching, Organization for Tropical Studies (2002)
  • Member, Mexican Academy of Sciences (2003)
  • Outstanding Researcher, Biology, National University of Mexico (2003)
  • Presidential Award in Ecology, Secretary of Environment, Mexico (2003)
  • Foreign Associate, US National Academy of Science (2004)
  • Foreign Member, American Academy of Arts and Sciences (2004)
  • Member, California Academy of Sciences (2008)
  • Medal of Honor (Science),, The State Congress, Morelos, Mexico (2015)
  • Merit in Ecology (Research), The Ecological Society of Mexico (2015)

Program Affiliations

  • Center for Latin American Studies

Professional Education

  • B.Sc., University of Morelos, Mexico, Biology (1972)
  • M.Sc., University of Wales, Ecology (1977)
  • Ph.D., University of Wales, Ecology (1980)

Community and International Work

  • Plant-animal interactions, Mexico, Costa Rica, Amazonia


    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



    Ongoing Project


    Opportunities for Student Involvement


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.


  • 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.



  • 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.


    Mexico, Costa Rica, Panama, Brazil.

  • 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.


    Mexico, Brazil, Kenya, the Channel Islands (Central Pacific)


    • Hillary Young, Professor, University of California Santa Barbara
  • 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.


    OSa Peninsula and Golfito Canton in Costa Rica


    • Willliam Durham, Professor, Stanford University

2016-17 Courses

Stanford Advisees

Graduate and Fellowship Programs

  • Biology (School of Humanities and Sciences) (Phd Program)

All Publications

  • Scattered trees and livestock grazing as keystones organisms for sustainable use and conservation of Mediterranean dehesas JOURNAL FOR NATURE CONSERVATION Lopez-Sanchez, A., Miguel, A. S., Dirzo, R., Roig, S. 2016; 33: 58-67
  • Anthropogenic disturbances jeopardize biodiversity conservation within tropical rainforest reserves PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA Martinez-Ramos, M., Ortiz-Rodriguez, I. A., Pinero, D., Dirzo, R., Sarukhan, J. 2016; 113 (19): 5323-5328


    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

  • Large wildlife removal drives immune defence increases in rodents FUNCTIONAL ECOLOGY Young, H. S., Dirzo, R., Helgen, K. M., McCauley, D. J., Nunn, C. L., Snyder, P., Veblen, K. E., Zhao, S., Ezenwa, V. O. 2016; 30 (5): 799-807
  • Does tropical forest fragmentation affect plant anti-herbivore defensive and nutritional traits? JOURNAL OF TROPICAL ECOLOGY Ruiz-Guerra, B., Guevara, R., Velazquez-Rosas, N., Dirzo, R. 2016; 32: 162-164
  • Livestock vs. wild ungulate management in the conservation of Mediterranean dehesas: Implications for oak regeneration FOREST ECOLOGY AND MANAGEMENT Lopez-Sanchez, A., Perea, R., Dirzo, R., Roig, S. 2016; 362: 99-106
  • Hemiparasite-host plant interactions in a fragmented landscape assessed via imaging spectroscopy and LiDAR ECOLOGICAL APPLICATIONS Barbosa, J. M., Sebastian-Gonzalez, E., Asner, G. P., Knapp, D. E., Anderson, C., Martin, R. E., Dirzo, R. 2016; 26 (1): 55-66

    View details for DOI 10.1890/14.2429

    View details for Web of Science ID 000369511000006

  • Does tropical forest fragmentation affect plant anti-herbivore defensive and nutritional traits? Journal of Tropical Ecology Ruiz-Guerra, B., Guevara, R., Velazquez-Rosas, N., Dirzo, R. 2016; 32: 162-164
  • Genetics-based interactions among plants, pathogens, and herbivores define arthropod community structure ECOLOGY Busby, P. E., Lamit, L. J., Keith, A. R., Newcombe, G., Gehring, C. A., Whitham, T. G., Dirzo, R. 2015; 96 (7): 1974-1984

    View details for DOI 10.1890/13-2031.1

    View details for Web of Science ID 000357525800024

  • Genetics-based interactions among plants, pathogens, and herbivores define arthropod community structure. Ecology Busby, P. E., Lamit, L. J., Keith, A. R., Newcombe, G., Gehring, C. A., Whitham, T. G., Dirzo, R. 2015; 96 (7): 1974-1984


    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

  • Drivers of Intensity and Prevalence of Flea Parasitism on Small Mammals in East African Savanna Ecosystems. journal of parasitology Young, H. S., Dirzo, R., McCauley, D. J., Agwanda, B., Cattaneo, L., Dittmar, K., Eckerlin, R. P., Fleischer, R. C., Helgen, L. E., Hintz, A., Montinieri, J., Zhao, S., Helgen, K. M. 2015; 101 (3): 327-335


    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

  • DRIVERS OF INTENSITY AND PREVALENCE OF FLEA PARASITISM ON SMALL MAMMALS IN EAST AFRICAN SAVANNA ECOSYSTEMS JOURNAL OF PARASITOLOGY Young, H. S., Dirzo, R., McCauley, D. J., Agwanda, B., Cattaneo, L., Dittmarjj, K., Eckerlin, R. P., Fleischer, R. C., Helgen, L. E., Hintz, A., Montinieri, J., Zhao, S., Helgen, K. M. 2015; 101 (3): 327-335

    View details for DOI 10.1645/14-684.1

    View details for Web of Science ID 000356539600009

  • Collapse of the world's largest herbivores. Science advances Ripple, W. J., Newsome, T. M., Wolf, C., Dirzo, R., Everatt, K. T., Galetti, M., Hayward, M. W., Kerley, G. I., Levi, T., Lindsey, P. A., Macdonald, D. W., Malhi, Y., Painter, L. E., Sandom, C. J., Terborgh, J., Van Valkenburgh, B. 2015; 1 (4)


    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

  • Effects of Land Use on Plague (Yersinia pestis) Activity in Rodents in Tanzania AMERICAN JOURNAL OF TROPICAL MEDICINE AND HYGIENE McCauley, D. J., Salkeld, D. J., Young, H. S., Makundi, R., Dirzo, R., Eckerlin, R. P., Lambin, E. F., Gaffikin, L., Barry, M., Helgen, K. M. 2015; 92 (4): 776-783


    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

  • Tropical Forest Fragmentation Affects Floral Visitors but Not the Structure of Individual-Based Palm-Pollinator Networks PLOS ONE Dattilo, W., Aguirre, A., Quesada, M., Dirzo, R. 2015; 10 (3)


    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

  • Context-dependent effects of large-wildlife declines on small-mammal communities in central Kenya ECOLOGICAL APPLICATIONS Young, H. S., McCauley, D. J., Dirzo, R., Goheen, J. R., Agwanda, B., Brook, C., Otarola-Castillo, E., Ferguson, A. W., Kinyua, S. N., McDonough, M. M., Palmer, T. M., Pringle, R. M., Young, T. P., Helgen, K. M. 2015; 25 (2): 348-360

    View details for DOI 10.1890/14-0995.1

    View details for Web of Science ID 000350556400004

  • Context-dependent effects of large-wildlife declines on small-mammal communities in central Kenya. Ecological applications Young, H. S., McCauley, D. J., Dirzo, R., Goheen, J. R., Agwanda, B., Brook, C., Otarola-Castillo, E., Ferguson, A. W., Kinyua, S. N., McDonough, M. M., Palmer, T. M., Pringle, R. M., Young, T. P., Helgen, K. M. 2015; 25 (2): 348-360


    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

  • Experimental defaunation of terrestrial mammalian herbivores alters tropical rainforest understorey diversity. Proceedings. Biological sciences / The Royal Society Camargo-Sanabria, A. A., Mendoza, E., Guevara, R., Martínez-Ramos, M., Dirzo, R. 2015; 282 (1800)


    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

  • Strategic Actions to Value, Conserve, and Restore the Natural Capital of Megadiversity Countries: The Case of Mexico BIOSCIENCE Sarukhan, J., Urquiza-Haas, T., Koleff, P., Carabias, J., Dirzo, R., Ezcurra, E., Cerdeira-Estrada, S., Soberon, J. 2015; 65 (2): 164-173
  • Long-term vegetation changes in a temperate forest impacted by climate change ECOSPHERE Oakes, L. E., Hennon, P. E., O'Hara, K. L., Dirzo, R. 2014; 5 (10)
  • Differentiating genetic and environmental drivers of plant-pathogen community interactions JOURNAL OF ECOLOGY Busby, P. E., Newcombe, G., Dirzo, R., Whitham, T. G. 2014; 102 (5): 1300-1309
  • Reconstructing past ecological networks: the reconfiguration of seed-dispersal interactions after megafaunal extinction. Oecologia Pires, M. M., Galetti, M., Donatti, C. I., Pizo, M. A., Dirzo, R., Guimarães, P. R. 2014; 175 (4): 1247-1256


    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

  • Defaunation in the Anthropocene SCIENCE Dirzo, R., Young, H. S., Galetti, M., Ceballos, G., Isaac, N. J., Collen, B. 2014; 345 (6195): 401-406


    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

  • 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 Young, H. S., Dirzo, R., Helgen, K. M., McCauley, D. J., Billeter, S. A., Kosoy, M. Y., Osikowicz, L. M., Salkeld, D. J., Young, T. P., Dittmar, K. 2014; 111 (19): 7036-7041


    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

  • Differential plant damage due to litterfall in palm-dominated forest stands in a Central Pacific atoll JOURNAL OF TROPICAL ECOLOGY Young, H. S., McCauley, D. J., Pollock, A., Dirzo, R. 2014; 30: 231-236
  • Integrating stand and soil properties to understand foliar nutrient dynamics during forest succession following slash-and-burn agriculture in the Bolivian Amazon. PloS one Broadbent, E. N., Almeyda Zambrano, A. M., Asner, G. P., Soriano, M., Field, C. B., de Souza, H. R., Peña-Claros, M., Adams, R. I., Dirzo, R., Giles, L. 2014; 9 (2)


    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

  • Integrating Stand and Soil Properties to Understand Foliar Nutrient Dynamics during Forest Succession Following Slash-and-Burn Agriculture in the Bolivian Amazon. PloS one Broadbent, E. N., Almeyda Zambrano, A. M., Asner, G. P., Soriano, M., Field, C. B., de Souza, H. R., Peña-Claros, M., Adams, R. I., Dirzo, R., Giles, L. 2014; 9 (2)

    View details for DOI 10.1371/journal.pone.0086042

    View details for PubMedID 24516525

  • Water stress strengthens mutualism among ants, trees, and scale insects. PLoS biology Pringle, E. G., Akçay, E., Raab, T. K., Dirzo, R., Gordon, D. M. 2013; 11 (11)


    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

  • Richness and Abundance of Ichneumonidae in a Fragmented Tropical Rain Forest NEOTROPICAL ENTOMOLOGY Ruiz-Guerra, B., Hanson, P., Guevara, R., Dirzo, R. 2013; 42 (5): 458-465
  • Consumer preference for seeds and seedlings of rare species impacts tree diversity at multiple scales OECOLOGIA Young, H. S., McCauley, D. J., Guevara, R., Dirzo, R. 2013; 172 (3): 857-867


    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

  • Genetic basis of pathogen community structure for foundation tree species in a common garden and in the wild JOURNAL OF ECOLOGY Busby, P. E., Newcombe, G., Dirzo, R., Whitham, T. G. 2013; 101 (4): 867-877
  • Effects of mammalian herbivore declines on plant communities: observations and experiments in an African savanna JOURNAL OF ECOLOGY Young, H. S., McCauley, D. J., Helgen, K. M., Goheen, J. R., Otarola-Castillo, E., Palmer, T. M., Pringle, R. M., Young, T. P., Dirzo, R. 2013; 101 (4): 1030-1041
  • Ecological and evolutionary consequences of living in a defaunated world BIOLOGICAL CONSERVATION Galetti, M., Dirzo, R. 2013; 163: 1-6
  • 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 Meli, P., Dirzo, R. 2013; 16 (2): 296-304
  • The roles of productivity and ecosystem size in determining food chain length in tropical terrestrial ecosystems ECOLOGY Young, H. S., McCauley, D. J., Dunbar, R. B., Hutson, M. S., Ter-Kuile, M., Dirzo, R. 2013; 94 (3): 692-701


    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

  • Plant defense, herbivory, and the growth of Cordia alliodora trees and their symbiotic Azteca ant colonies OECOLOGIA Pringle, E. G., Dirzo, R., Gordon, D. M. 2012; 170 (3): 677-685


    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

  • Averting biodiversity collapse in tropical forest protected areas NATURE Laurance, W. F., Useche, D. C., Rendeiro, J., Kalka, M., Bradshaw, C. J., Sloan, S. P., Laurance, S. G., Campbell, M., Abernethy, K., Alvarez, P., Arroyo-Rodriguez, V., Ashton, P., Benitez-Malvido, J., Blom, A., Bobo, K. S., Cannon, C. H., Cao, M., Carroll, R., Chapman, C., Coates, R., Cords, M., Danielsen, F., De Dijn, B., Dinerstein, E., Donnelly, M. A., Edwards, D., Edwards, F., Farwig, N., Fashing, P., Forget, P., Foster, M., Gale, G., Harris, D., Harrison, R., Hart, J., Karpanty, S., Kress, W. J., Krishnaswamy, J., Logsdon, W., Lovett, J., Magnusson, W., Maisels, F., Marshall, A. R., McClearn, D., Mudappa, D., Nielsen, M. R., Pearson, R., Pitman, N., van der Ploeg, J., Plumptre, A., Poulsen, J., Quesada, M., Rainey, H., Robinson, D., Roetgers, C., Rovero, F., Scatena, F., Schulze, C., Sheil, D., Struhsaker, T., Terborgh, J., Thomas, D., Timm, R., Urbina-Cardona, J. N., Vasudevan, K., Wright, S. J., Arias-G, J. C., Arroyo, L., Ashton, M., Auzel, P., Babaasa, D., Babweteera, F., Baker, P., Banki, O., Bass, M., Bila-Isia, I., Blake, S., Brockelman, W., Brokaw, N., Bruehl, C. A., Bunyavejchewin, S., Chao, J., Chave, J., Chellam, R., Clark, C. J., Clavijo, J., Congdon, R., Corlett, R., Dattaraja, H. S., Dave, C., Davies, G., Beisiegel, B. d., da Silva, R. d., Di Fiore, A., Diesmos, A., Dirzo, R., Doran-Sheehy, D., Eaton, M., Emmons, L., Estrada, A., Ewango, C., Fedigan, L., Feer, F., Fruth, B., Willis, J. G., Goodale, U., Goodman, S., Guix, J. C., Guthiga, P., Haber, W., Hamer, K., Herbinger, I., Hill, J., Huang, Z., Sun, I. F., Ickes, K., Itoh, A., Ivanauskas, N., Jackes, B., Janovec, J., Janzen, D., Jiangming, M., Jin, C., Jones, T., Justiniano, H., Kalko, E., Kasangaki, A., Killeen, T., King, H., Klop, E., Knott, C., Kone, I., Kudavidanage, E., Ribeiro, J. L., Lattke, J., Laval, R., Lawton, R., Leal, M., Leighton, M., Lentino, M., Leonel, C., Lindsell, J., Ling-Ling, L., Linsenmair, K. E., Losos, E., Lugo, A., Lwanga, J., Mack, A. L., Martins, M., McGraw, W. S., McNab, R., Montag, L., Thompson, J. M., Nabe-Nielsen, J., Nakagawa, M., Nepal, S., Norconk, M., Novotny, V., O'Donnell, S., Opiang, M., Ouboter, P., Parker, K., Parthasarathy, N., Pisciotta, K., Prawiradilaga, D., Pringle, C., Rajathurai, S., Reichard, U., Reinartz, G., Renton, K., Reynolds, G., Reynolds, V., Riley, E., Roedel, M., Rothman, J., Round, P., Sakai, S., Sanaiotti, T., Savini, T., Schaab, G., Seidensticker, J., Siaka, A., Silman, M. R., Smith, T. B., de Almeida, S. S., Sodhi, N., Stanford, C., Stewart, K., Stokes, E., Stoner, K. E., Sukumar, R., Surbeck, M., Tobler, M., Tscharntke, T., Turkalo, A., Umapathy, G., Van Weerd, M., Rivera, J. V., Venkataraman, M., Venn, L., Verea, C., de Castilho, C. V., Waltert, M., Wang, B., Watts, D., Weber, W., West, P., Whitacre, D., Whitney, K., Wilkie, D., Williams, S., Wright, D. D., Wright, P., Xiankai, L., Yonzon, P., Zamzani, F. 2012; 489 (7415): 290-?


    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

  • Effects of Spatial Subsidies and Habitat Structure on the Foraging Ecology and Size of Geckos PLOS ONE Briggs, A. A., Young, H. S., McCauley, D. J., Hathaway, S. A., Dirzo, R., Fisher, R. N. 2012; 7 (8)


    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 Web of Science ID 000307380900010

    View details for PubMedID 22899995

  • Diversification and phylogeographic structure in widespread Azteca plant-ants from the northern Neotropics MOLECULAR ECOLOGY Pringle, E. G., Ramirez, S. R., Bonebrake, T. C., Gordon, D. M., Dirzo, R. 2012; 21 (14): 3576-3592


    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

  • From wing to wing: the persistence of long ecological interaction chains in less-disturbed ecosystems SCIENTIFIC REPORTS McCauley, D. J., DeSalles, P. A., Young, H. S., Dunbar, R. B., Dirzo, R., Mills, M. M., Micheli, F. 2012; 2


    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

  • The effect of land use change and ecotourism on biodiversity: a case study of Manuel Antonio, Costa Rica, from 1985 to 2008 LANDSCAPE ECOLOGY Broadbent, E. N., Zambrano, A. M., Dirzo, R., Durham, W. H., Driscoll, L., Gallagher, P., Salters, R., Schultz, J., Colmenares, A., Randolph, S. G. 2012; 27 (5): 731-744
  • Consequences of Fragmentation of Tropical Moist Forest for Birds and Their Role in Predation of Herbivorous Insects BIOTROPICA Ruiz-Guerra, B., Renton, K., Dirzo, R. 2012; 44 (2): 228-236
  • Intersexual comparison of DNA content by flow cytometry, and chromosome number in four dioecious Chamaedorea palms from Mexico CARYOLOGIA Cepeda-Cornejo, V., Palomino, G., Mendez, I., Dirzo, R. 2012; 65 (4): 263-270


    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

  • Analysis of a hyper-diverse seed dispersal network: modularity and underlying mechanisms ECOLOGY LETTERS Donatti, C. I., Guimaraes, P. R., Galetti, M., Pizo, M. A., Marquitti, F. M., Dirzo, R. 2011; 14 (8): 773-781


    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

  • Differential diameter-size effects of forest management on tree species richness and community structure: implications for conservation BIODIVERSITY AND CONSERVATION Gutierrez-Granados, G., Perez-Salicrup, D. R., Dirzo, R. 2011; 20 (7): 1571-1585
  • Distinct Leaf-trait Syndromes of Evergreen and Deciduous Trees in a Seasonally Dry Tropical Forest BIOTROPICA Pringle, E. G., Adams, R. I., Broadbent, E., Busby, P. E., Donatti, C. I., Kurten, E. L., Renton, K., Dirzo, R. 2011; 43 (3): 299-308
  • A Novel Method to Improve Individual Animal Identification Based on Camera-Trapping Data JOURNAL OF WILDLIFE MANAGEMENT Mendoza, E., Martineau, P. R., Brenner, E., Dirzo, R. 2011; 75 (4): 973-979

    View details for DOI 10.1002/jwmg.120

    View details for Web of Science ID 000291818100025



    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

  • Indirect benefits of symbiotic coccoids for an ant-defended myrmecophytic tree ECOLOGY Pringle, E. G., Dirzo, R., Gordon, D. M. 2011; 92 (1): 37-46


    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

  • 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 Aguirre, A., Guevara, R., Dirzo, R. 2011; 27: 25-33
  • The coconut palm, Cocos nucifera, impacts forest composition and soil characteristics at Palmyra Atoll, Central Pacific JOURNAL OF VEGETATION SCIENCE Young, H. S., Raab, T. K., McCauley, D. J., Briggs, A. A., Dirzo, R. 2010; 21 (6): 1058-1068
  • Plant stages with biotic, indirect defences are more palatable and suffer less herbivory than their undefended counterparts BIOLOGICAL JOURNAL OF THE LINNEAN SOCIETY Llandres, A. L., Rodriguez-Girones, M. A., Dirzo, R. 2010; 101 (3): 536-543
  • Delineation of biogeomorphic land units across a tropical natural and humanized terrain in Los Tuxtlas, Veracruz, Mexico GEOMORPHOLOGY Concepcion Garcia-Aguirre, M., Alvarez, R., Dirzo, R., Ortiz, M. A., Eng, M. M. 2010; 121 (3-4): 245-256
  • Experimental defoliation affects male but not female reproductive performance of the tropical monoecious plant Croton suberosus (Euphorbiaceae) ANNALS OF BOTANY Narbona, E., Dirzo, R. 2010; 106 (2): 359-369


    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



    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

  • Sex-Related Differences in Reproductive Allocation, Growth, Defense and Herbivory in Three Dioecious Neotropical Palms PLOS ONE Cepeda-Cornejo, V., Dirzo, R. 2010; 5 (3)


    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

  • Importance of the lilac-crowned parrot in pre-dispersal seed predation of Astronium graveolens in a Mexican tropical dry forest JOURNAL OF TROPICAL ECOLOGY Ines Villasenor-Sanchez, E., Dirzo, R., Renton, K. 2010; 26: 227-236
  • 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 Young, H. S., McCauley, D. J., Dunbar, R. B., Dirzo, R. 2010; 107 (5): 2072-2077


    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

  • Insect herbivory declines with forest fragmentation and covaries with plant regeneration mode: evidence from a Mexican tropical rain forest OIKOS Ruiz-Guerra, B., Guevara, R., Mariano, N. A., Dirzo, R. 2010; 119 (2): 317-325
  • Prevalence of Tree Regeneration by Sprouting and Seeding Along a Rainfall Gradient in Hawai'i BIOTROPICA Busby, P. E., Vitousek, P., Dirzo, R. 2010; 42 (1): 80-86
  • Resource partitioning by species but not sex in sympatric boobies in the central Pacific Ocean MARINE ECOLOGY PROGRESS SERIES Young, H. S., Shaffer, S. A., McCauley, D. J., Foley, D. G., Dirzo, R., Block, B. A. 2010; 403: 291-301

    View details for DOI 10.3354/meps08478

    View details for Web of Science ID 000276799000024

  • Indirect effects of timber extraction on plant recruitment and diversity via reductions in abundance of frugivorous spider monkeys JOURNAL OF TROPICAL ECOLOGY Gutierrez-Granados, G., Dirzo, R. 2010; 26: 45-52
  • Niche partitioning among and within sympatric tropical seabirds revealed by stable isotope analysis MARINE ECOLOGY PROGRESS SERIES Young, H. S., McCauley, D. J., Dirzo, R., Dunbar, R. B., Shaffer, S. A. 2010; 416: 285-294

    View details for DOI 10.3354/meps08756

    View details for Web of Science ID 000283446400023



    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

  • Morphological variation in the flowers of Jacaratia mexicana A. DC. (Caricaceae), a subdioecious tree PLANT BIOLOGY Aguirre, A., Vallejo-Marin, M., Piedra-Malagon, E. M., Cruz-Ortega, R., Dirzo, R. 2009; 11 (3): 417-424


    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

  • Effects of fragmentation on pollinator abundance and fruit set of an abundant understory palm in a Mexican tropical forest BIOLOGICAL CONSERVATION Aguirre, A., Dirzo, R. 2008; 141 (2): 375-384
  • Effects of Amazonian forest fragmentation on the interaction between plants, insect herbivores, and their natural enemies JOURNAL OF TROPICAL ECOLOGY Faveri, S. B., Vasconcelos, H. L., Dirzo, R. 2008; 24: 57-64
  • Seed-size variation determines interspecific differential predation by mammals in a neotropical rain forest OIKOS Mendoza, E., Dirzo, R. 2007; 116 (11): 1841-1852
  • Ontogenetic switches from plant resistance to tolerance: minimizing costs with age? ECOLOGY LETTERS Boege, K., Dirzo, R., Siemens, D., Brown, P. 2007; 10 (3): 177-187


    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

  • Floristic diversity of sabal palmetto woodland: an endemic and endangered vegetation type from Mexico BIODIVERSITY AND CONSERVATION Lopez, J. C., Dirzo, R. 2007; 16 (3): 807-825
  • Variation in sexual expression in Jacaratia mexicana (Caricaceae) in southern Mexico: Frequency and relative seed performance of fruit-producing males BIOTROPICA Aguirre, A., Vallejo-Marin, M., Salazar-Goroztieta, L., Arias, D. M., Dirzo, R. 2007; 39 (1): 79-86
  • Biased seed rain in forest edges: Evidence from the Brazilian Atlantic forest BIOLOGICAL CONSERVATION de Melo, F. P., Dirzo, R., Tabarelli, M. 2006; 132 (1): 50-60
  • The evolution of ecology in Mexico: facing challenges and preparing for the future FRONTIERS IN ECOLOGY AND THE ENVIRONMENT Martinez, M. L., Manson, R. H., Balvanera, P., Dirzo, R., Soberon, J., Garcia-Barrios, L., Martinez-Ramos, M., Moreno-Casasola, P., Rosenzweig, L., Sarukhan, J. 2006; 4 (5): 259-267
  • An endangered oasis of aquatic microbial biodiversity in the Chihuahuan desert PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA Souza, V., Espinosa-Asuar, L., Escalante, A. E., Eguiarte, L. E., Farmer, J., Forney, L., Lloret, L., Rodriguez-Martinez, J. M., Soberon, X., Dirzo, R., Elser, J. J. 2006; 103 (17): 6565-6570


    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

  • Simulated seed predation reveals a variety of germination responses of neotropical rain forest species AMERICAN JOURNAL OF BOTANY Vallejo-Marin, M., DOMINGUEZ, C. A., Dirzo, R. 2006; 93 (3): 369-376


    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

  • A quantitative analysis of forest fragmentation in Los Tuxtlas, southeast Mexico: patterns and implications for conservation REVISTA CHILENA DE HISTORIA NATURAL Mendoza, E., Fay, J., Dirzo, R. 2005; 78 (3): 451-467
  • Myrmecophily: Plants with their own army INTERCIENCIA Del Val, E., Dirzo, R. 2004; 29 (12): 673-?
  • 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 Cuevas-Reyes, P., Quesada, M., Hanson, P., Dirzo, R., Oyama, K. 2004; 92 (4): 707-716
  • Intraspecific variation in growth, defense and herbivory in Dialium guianense (Caesalpiniaceae) mediated by edaphic heterogeneity PLANT ECOLOGY Boege, K., Dirzo, R. 2004; 175 (1): 59-69
  • Global state of biodiversity and loss Annual Review of Environment and Natural Resources Rodolfo Dirzo, Peter Raven 2003; 28: 137-167
  • Global state of biodiversity and loss ANNUAL REVIEW OF ENVIRONMENT AND RESOURCES Dirzo, R., Raven, P. H. 2003; 28: 137-167
  • Does ontogeny cause changes in the defensive strategies of the myrmecophyte Cecropia peltata? PLANT ECOLOGY Del Val, E., Dirzo, R. 2003; 169 (1): 35-41
  • Genetic divergence among Mexican populations of red mangrove (Rhizophora mangle): geographic and historic effects EVOLUTIONARY ECOLOGY RESEARCH Nunez-Farfan, J., DOMINGUEZ, C. A., Eguiarte, L. E., Cornejo, A., Quijano, M., Vargas, J., Dirzo, R. 2002; 4 (7): 1049-1064
  • The causes of land-use and land-cover change: moving beyond the myths GLOBAL ENVIRONMENTAL CHANGE-HUMAN AND POLICY DIMENSIONS Lambin, E. F., Turner, B. L., Geist, H. J., Agbola, S. B., Angelsen, A., Bruce, J. W., Coomes, O. T., Dirzo, R., Fischer, G., Folke, C., George, P. S., Homewood, K., Imbernon, J., Leemans, R., Li, X. B., Moran, E. F., Mortimore, M., Ramakrishnan, P. S., Richards, J. F., Skanes, H., STEFFEN, W., Stone, G. D., Svedin, U., Veldkamp, T. A., Vogel, C., Xu, J. C. 2001; 11 (4): 261-269
  • Biodiversity - Global biodiversity scenarios for the year 2100 SCIENCE Sala, O. E., Chapin, F. S., Armesto, J. J., Berlow, E., Bloomfield, J., Dirzo, R., Huber-Sanwald, E., Huenneke, L. F., Jackson, R. B., Kinzig, A., Leemans, R., Lodge, D. M., Mooney, H. A., Oesterheld, M., Poff, N. L., Sykes, M. T., Walker, B. H., Walker, M., Wall, D. H. 2000; 287 (5459): 1770-1774
  • Global biodiversity scenarios for the year 2100. Science Sala, O. E., Chapin, F. S., Armesto, J. J., Berlow, E., Bloomfield, J., Dirzo, R., Huber-Sanwald, E., Huenneke, L. F., Jackson, R. B., Kinzig, A., Leemans, R., Lodge, D. M., Mooney, H. A., Oesterheld, M., Poff, N. L., Sykes, M. T., Walker, B. H., Walker, M., Wall, D. H. 2000; 287 (5459): 1770-1774


    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

  • Deforestation in Lacandonia (southeast Mexico): evidence for the declaration of the northernmost tropical hot-spot BIODIVERSITY AND CONSERVATION Mendoza, E., Dirzo, R. 1999; 8 (12): 1621-1641
  • Consumption of macro-fungi by invertebrates in a Mexican tropical cloud forest: do fruit body characteristics matter? JOURNAL OF TROPICAL ECOLOGY Guevara, R., Dirzo, R. 1999; 15: 603-617
  • Ecological science and the human predicament SCIENCE Bazzaz, F., Ceballos, G., Davis, M., Dirzo, R., Ehrlich, P. R., Eisner, T., Levin, S., Lawton, J. H., Lubchenco, J., Matson, P. A., Mooney, H. A., Raven, P. H., Roughgarden, J. E., Sarukhan, J., Tilman, G. D., Vitousek, P., Wall, D. H., Wilson, E. O., Woodwell, G. M. 1998; 282 (5390): 879-879
  • Flower morphometry of Rhizophora mangle (Rhizophoraceae): Geographical variation in Mexican populations AMERICAN JOURNAL OF BOTANY DOMINGUEZ, C. A., Eguiarte, L. E., Nunez-Farfan, J., Dirzo, R. 1998; 85 (5): 637-643


    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

  • 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 Guevara, R., Dirzo, R. 1998; 76 (4): 596-601
  • Mating system consequences on resistance to herbivory and life history traits in Datura stramonium AMERICAN JOURNAL OF BOTANY NUNEZFARFAN, J., CabralesVargas, R. A., Dirzo, R. 1996; 83 (8): 1041-1049