Bio


Paul Ehrlich is the Bing Professor of Population Studies, Emeritus and President of the Center for Conservation Biology at Stanford. He has carried out field, laboratory and theoretical research on the dynamics and genetics of insect populations, the evolutionary interactions of plants and herbivores, the behavioral ecology of birds and reef fishes, the effects of crowding on human beings, human cultural evolution and health problems related to industrialization. He is author and coauthor of more than 1,100 scientific papers and articles and over 40 books. Ehrlich is a member of the U.S. National Academy of Sciences, the American Philosophical Society and a Foreign Member of the Royal Society. Among his many other honors is the Royal Swedish Academy of Sciences, Crafoord Prize (an explicit replacement for the Nobel Prize). He has appeared on more than 1,000 TV and radio programs and was a correspondent for NBC News.

Academic Appointments


Current Research and Scholarly Interests


The role of the social sciences in dealing with global change

Graduate and Fellowship Programs


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

All Publications


  • The Climate Change Challenge and Barriers to the Exercise of Foresight Intelligence BIOSCIENCE Ross, L., Arrow, K., Cialdini, R., Diamond-Smith, N., Diamond, J., Dunne, J., Feldman, M., Horn, R., Kennedy, D., Murphy, C., Pirages, D., Smith, K., York, R., Ehrlich, P. 2016; 66 (5): 363-370
  • Confronting and resolving competing values behind conservation objectives PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA Karpa, D. S., Mendenhall, C. D., Callaway, E., Frishkoff, L. O., Kareiva, P. M., Ehrlich, P. R., Daily, G. C. 2015; 112 (35): 11132-11137

    Abstract

    Diverse motivations for preserving nature both inspire and hinder its conservation. Optimal conservation strategies may differ radically depending on the objective. For example, creating nature reserves may prevent extinctions through protecting severely threatened species, whereas incentivizing farmland hedgerows may benefit people through bolstering pest-eating or pollinating species. Win-win interventions that satisfy multiple objectives are alluring, but can also be elusive. To achieve better outcomes, we developed and implemented a practical typology of nature conservation framed around seven common conservation objectives. Using an intensively studied bird assemblage in southern Costa Rica as a case study, we applied the typology in the context of biodiversity's most pervasive threat: habitat conversion. We found that rural habitats in a varied tropical landscape, comprising small farms, villages, forest fragments, and forest reserves, provided biodiversity-driven processes that benefit people, such as pollination, seed dispersal, and pest consumption. However, species valued for their rarity, endemism, and evolutionary distinctness declined in farmland. Conserving tropical forest on farmland increased species that international tourists value, but not species discussed in Costa Rican newspapers. Despite these observed trade-offs, our analyses also revealed promising synergies. For example, we found that maintaining forest cover surrounding farms in our study region would likely enhance most conservation objectives at minimal expense to others. Overall, our typology provides a framework for resolving the competing objectives of modern conservation.

    View details for DOI 10.1073/pnas.1504788112

    View details for Web of Science ID 000360383200080

    View details for PubMedCentralID PMC4568250

  • Confronting and resolving competing values behind conservation objectives. Proceedings of the National Academy of Sciences of the United States of America Karp, D. S., Mendenhall, C. D., Callaway, E., Frishkoff, L. O., Kareiva, P. M., Ehrlich, P. R., Daily, G. C. 2015; 112 (35): 11132-11137

    Abstract

    Diverse motivations for preserving nature both inspire and hinder its conservation. Optimal conservation strategies may differ radically depending on the objective. For example, creating nature reserves may prevent extinctions through protecting severely threatened species, whereas incentivizing farmland hedgerows may benefit people through bolstering pest-eating or pollinating species. Win-win interventions that satisfy multiple objectives are alluring, but can also be elusive. To achieve better outcomes, we developed and implemented a practical typology of nature conservation framed around seven common conservation objectives. Using an intensively studied bird assemblage in southern Costa Rica as a case study, we applied the typology in the context of biodiversity's most pervasive threat: habitat conversion. We found that rural habitats in a varied tropical landscape, comprising small farms, villages, forest fragments, and forest reserves, provided biodiversity-driven processes that benefit people, such as pollination, seed dispersal, and pest consumption. However, species valued for their rarity, endemism, and evolutionary distinctness declined in farmland. Conserving tropical forest on farmland increased species that international tourists value, but not species discussed in Costa Rican newspapers. Despite these observed trade-offs, our analyses also revealed promising synergies. For example, we found that maintaining forest cover surrounding farms in our study region would likely enhance most conservation objectives at minimal expense to others. Overall, our typology provides a framework for resolving the competing objectives of modern conservation.

    View details for DOI 10.1073/pnas.1504788112

    View details for PubMedID 26283400

  • Transformational change: creating a safe operating space for humanity ECOLOGY AND SOCIETY Mcalpine, C. A., Seabrook, L. M., Ryan, J. G., Feeney, B. J., Ripple, W. J., Ehrlich, A. H., Ehrlich, P. R. 2015; 20 (1)
  • Conservation biology and the endarkenment. Ambio Ehrlich, P. R. 2014; 43 (7): 847-848

    View details for DOI 10.1007/s13280-014-0551-6

    View details for PubMedID 25238979

    View details for PubMedCentralID PMC4190151

  • From global change to a butterfly flapping: biophysics and behaviour affect tropical climate change impacts. Proceedings. Biological sciences / The Royal Society Bonebrake, T. C., Boggs, C. L., Stamberger, J. A., Deutsch, C. A., Ehrlich, P. R. 2014; 281 (1793)

    Abstract

    Difficulty in characterizing the relationship between climatic variability and climate change vulnerability arises when we consider the multiple scales at which this variation occurs, be it temporal (from minute to annual) or spatial (from centimetres to kilometres). We studied populations of a single widely distributed butterfly species, Chlosyne lacinia, to examine the physiological, morphological, thermoregulatory and biophysical underpinnings of adaptation to tropical and temperate climates. Microclimatic and morphological data along with a biophysical model documented the importance of solar radiation in predicting butterfly body temperature. We also integrated the biophysics with a physiologically based insect fitness model to quantify the influence of solar radiation, morphology and behaviour on warming impact projections. While warming is projected to have some detrimental impacts on tropical ectotherms, fitness impacts in this study are not as negative as models that assume body and air temperature equivalence would suggest. We additionally show that behavioural thermoregulation can diminish direct warming impacts, though indirect thermoregulatory consequences could further complicate predictions. With these results, at multiple spatial and temporal scales, we show the importance of biophysics and behaviour for studying biodiversity consequences of global climate change, and stress that tropical climate change impacts are likely to be context-dependent.

    View details for DOI 10.1098/rspb.2014.1264

    View details for PubMedID 25165769

  • Does aquaculture add resilience to the global food system? Proceedings of the National Academy of Sciences of the United States of America Troell, M., Naylor, R. L., Metian, M., Beveridge, M., Tyedmers, P. H., Folke, C., Arrow, K. J., Barrett, S., Crépin, A., Ehrlich, P. R., Gren, A., Kautsky, N., Levin, S. A., Nyborg, K., Österblom, H., Polasky, S., Scheffer, M., Walker, B. H., Xepapadeas, T., de Zeeuw, A. 2014; 111 (37): 13257-13263

    Abstract

    Aquaculture is the fastest growing food sector and continues to expand alongside terrestrial crop and livestock production. Using portfolio theory as a conceptual framework, we explore how current interconnections between the aquaculture, crop, livestock, and fisheries sectors act as an impediment to, or an opportunity for, enhanced resilience in the global food system given increased resource scarcity and climate change. Aquaculture can potentially enhance resilience through improved resource use efficiencies and increased diversification of farmed species, locales of production, and feeding strategies. However, aquaculture's reliance on terrestrial crops and wild fish for feeds, its dependence on freshwater and land for culture sites, and its broad array of environmental impacts diminishes its ability to add resilience. Feeds for livestock and farmed fish that are fed rely largely on the same crops, although the fraction destined for aquaculture is presently small (∼4%). As demand for high-value fed aquaculture products grows, competition for these crops will also rise, as will the demand for wild fish as feed inputs. Many of these crops and forage fish are also consumed directly by humans and provide essential nutrition for low-income households. Their rising use in aquafeeds has the potential to increase price levels and volatility, worsening food insecurity among the most vulnerable populations. Although the diversification of global food production systems that includes aquaculture offers promise for enhanced resilience, such promise will not be realized if government policies fail to provide adequate incentives for resource efficiency, equity, and environmental protection.

    View details for DOI 10.1073/pnas.1404067111

    View details for PubMedID 25136111

    View details for PubMedCentralID PMC4169979

  • Economic development and coastal ecosystem change in China SCIENTIFIC REPORTS He, Q., Bertness, M. D., Bruno, J. F., Li, B., Chen, G., Coverdale, T. C., Altieri, A. H., Bai, J., Sun, T., Pennings, S. C., Liu, J., Ehrlich, P. R., Cui, B. 2014; 4

    Abstract

    Despite their value, coastal ecosystems are globally threatened by anthropogenic impacts, yet how these impacts are driven by economic development is not well understood. We compiled a multifaceted dataset to quantify coastal trends and examine the role of economic growth in China's coastal degradation since the 1950s. Although China's coastal population growth did not change following the 1978 economic reforms, its coastal economy increased by orders of magnitude. All 15 coastal human impacts examined increased over time, especially after the reforms. Econometric analysis revealed positive relationships between most impacts and GDP across temporal and spatial scales, often lacking dropping thresholds. These relationships generally held when influences of population growth were addressed by analyzing per capita impacts, and when population density was included as explanatory variables. Historical trends in physical and biotic indicators showed that China's coastal ecosystems changed little or slowly between the 1950s and 1978, but have degraded at accelerated rates since 1978. Thus economic growth has been the cause of accelerating human damage to China's coastal ecosystems. China's GDP per capita remains very low. Without strict conservation efforts, continuing economic growth will further degrade China's coastal ecosystems.

    View details for DOI 10.1038/srep05995

    View details for Web of Science ID 000340593000007

    View details for PubMedID 25104138

    View details for PubMedCentralID PMC4125988

  • Countryside biogeography of Neotropical reptiles and amphibians ECOLOGY Mendenhall, C. D., Frishkoff, L. O., Santos-Barrera, G., Pacheco, J., Mesfun, E., Mendoza Quijano, F., Ehrlich, P. R., Ceballos, G., Daily, G. C., Pringle, R. M. 2014; 95 (4): 856-870

    Abstract

    The future of biodiversity and ecosystem services depends largely on the capacity of human-dominated ecosystems to support them, yet this capacity remains largely unknown. Using the framework of countryside biogeography, and working in the Las Cruces system of Coto Brus, Costa Rica, we assessed reptile and amphibian assemblages within four habitats that typify much of the Neotropics: sun coffee plantations (12 sites), pasture (12 sites), remnant forest elements (12 sites), and a larger, contiguous protected forest (3 sites in one forest). Through analysis of 1678 captures of 67 species, we draw four primary conclusions. First, we found that the majority of reptile (60%) and amphibian (70%) species in this study used an array of habitat types, including coffee plantations and actively grazed pastures. Second, we found that coffee plantations and pastures hosted rich, albeit different and less dense, reptile and amphibian biodiversity relative to the 326-ha Las Cruces Forest Reserve and neighboring forest elements. Third, we found that the small ribbons of "countryside forest elements" weaving through farmland collectively increased the effective size of a 326-ha local forest reserve 16-fold for reptiles and 14-fold for amphibians within our 236-km2 study area. Therefore, countryside forest elements, often too small for most remote sensing techniques to identify, are contributing -95% of the available habitat for forest-dependent reptiles and amphibians in our largely human-dominated study region. Fourth, we found large and pond-reproducing amphibians to prefer human-made habitats, whereas small, stream-reproducing, and directly developing species are more dependent on forest elements. Our investigation demonstrates that tropical farming landscapes can support substantial reptile and amphibian biodiversity. Our approach provides a framework for estimating the conservation value of the complex working landscapes that constitute roughly half of the global land surface, and which are experiencing intensification pressure worldwide.

    View details for DOI 10.1890/12-2017.1

    View details for Web of Science ID 000334573600007

  • Forest bolsters bird abundance, pest control and coffee yield ECOLOGY LETTERS Karp, D. S., Mendenhall, C. D., Sandi, R. F., Chaumont, N., Ehrlich, P. R., Hadly, E. A., Daily, G. C. 2013; 16 (11): 1339-1347

    Abstract

    Efforts to maximise crop yields are fuelling agricultural intensification, exacerbating the biodiversity crisis. Low-intensity agricultural practices, however, may not sacrifice yields if they support biodiversity-driven ecosystem services. We quantified the value native predators provide to farmers by consuming coffee's most damaging insect pest, the coffee berry borer beetle (Hypothenemus hampei). Our experiments in Costa Rica showed birds reduced infestation by ~ 50%, bats played a marginal role, and farmland forest cover increased pest removal. We identified borer-consuming bird species by assaying faeces for borer DNA and found higher borer-predator abundances on more forested plantations. Our coarse estimate is that forest patches doubled pest control over 230 km2 by providing habitat for ~ 55 000 borer-consuming birds. These pest-control services prevented US$75-US$310 ha-year(-1) in damage, a benefit per plantation on par with the average annual income of a Costa Rican citizen. Retaining forest and accounting for pest control demonstrates a win-win for biodiversity and coffee farmers.

    View details for DOI 10.1111/ele.12173

    View details for Web of Science ID 000325976500002

    View details for PubMedID 23981013

  • Future collapse: how optimistic should we be? Proceedings. Biological sciences / The Royal Society Ehrlich, P. R., Ehrlich, A. H. 2013; 280 (1767): 20131373-?

    View details for DOI 10.1098/rspb.2013.1373

    View details for PubMedID 23902905

    View details for PubMedCentralID PMC3735257

  • Pervasive Externalities at the Population, Consumption, and Environment Nexus SCIENCE Dasgupta, P. S., Ehrlich, P. R. 2013; 340 (6130): 324-328

    Abstract

    Growing concerns that contemporary patterns of economic development are unsustainable have given rise to an extensive empirical literature on population growth, consumption increases, and our growing use of nature's products and services. However, far less has been done to reach a theoretical understanding of the socio-ecological processes at work at the population-consumption-environment nexus. In this Research Article, we highlight the ubiquity of externalities (which are the unaccounted for consequences for others, including future people) of decisions made by each of us on reproduction, consumption, and the use of our natural environment. Externalities, of which the "tragedy of the commons" remains the most widely discussed illustration, are a cause of inefficiency in the allocation of resources across space, time, and contingencies; in many situations, externalities accentuate inequity as well. Here, we identify and classify externalities in consumption and reproductive decisions and use of the natural environment so as to construct a unified theoretical framework for the study of data drawn from the nexus. We show that externalities at the nexus are not self-correcting in the marketplace. We also show that fundamental nonlinearities, built into several categories of externalities, amplify the socio-ecological processes operating at the nexus. Eliminating the externalities would, therefore, require urgent collective action at both local and global levels.

    View details for DOI 10.1126/science.1224664

    View details for Web of Science ID 000317657500047

    View details for PubMedID 23599486

  • Social-ecological systems as complex adaptive systems: modeling and policy implications ENVIRONMENT AND DEVELOPMENT ECONOMICS Levin, S., Xepapadeas, T., Crepin, A., Norberg, J., De Zeeuw, A., Folke, C., Hughes, T., Arrow, K., Barrett, S., Daily, G., Ehrlich, P., Kautsky, N., Maler, K., Polasky, S., Troell, M., Vincent, J. R., Walker, B. 2013; 18: 111-132
  • Can a collapse of global civilization be avoided? PROCEEDINGS OF THE ROYAL SOCIETY B-BIOLOGICAL SCIENCES Ehrlich, P. R., Ehrlich, A. H. 2013; 280 (1754)

    Abstract

    Environmental problems have contributed to numerous collapses of civilizations in the past. Now, for the first time, a global collapse appears likely. Overpopulation, overconsumption by the rich and poor choices of technologies are major drivers; dramatic cultural change provides the main hope of averting calamity.

    View details for DOI 10.1098/rspb.2012.2845

    View details for Web of Science ID 000313663700017

    View details for PubMedID 23303549

    View details for PubMedCentralID PMC3574335

  • Social Norms and Global Environmental Challenges: The Complex Interaction of Behaviors, Values, and Policy BIOSCIENCE Kinzig, A. P., Ehrlich, P. R., Alston, L. J., Arrow, K., Barrett, S., Buchman, T. G., Daily, G. C., Levin, B., Levin, S., Oppenheimer, M., Ostrom, E., Saari, D. 2013; 63 (3): 164-175

    Abstract

    Government policies are needed when people's behaviors fail to deliver the public good. Those policies will be most effective if they can stimulate long-term changes in beliefs and norms, creating and reinforcing the behaviors needed to solidify and extend the public good.It is often the short-term acceptability of potential policies, rather than their longer-term efficacy, that determines their scope and deployment. The policy process should consider both time scales. The academy, however, has provided insufficient insight on the coevolution of social norms and different policy instruments, thus compromising the capacity of decision makers to craft effective solutions to the society's most intractable environmental problems. Life scientists could make fundamental contributions to this agenda through targeted research on the emergence of social norms.

    View details for DOI 10.1525/bio.2013.63.3.5

    View details for Web of Science ID 000322048200005

    View details for PubMedCentralID PMC4136381

  • The decoupling of human and natural systems makes me very grumpy Annual Forum on Grumpy Scientists: the Ecological Conscience of a Nation Ehrlich, P. R. ROYAL ZOOLOGICAL SOC NEW SOUTH WALES. 2013: 9–13
  • Intensive agriculture erodes beta-diversity at large scales ECOLOGY LETTERS Karp, D. S., Rominger, A. J., Zook, J., Ranganathan, J., Ehrlich, P. R., Daily, G. C. 2012; 15 (9): 963-970

    Abstract

    Biodiversity is declining from unprecedented land conversions that replace diverse, low-intensity agriculture with vast expanses under homogeneous, intensive production. Despite documented losses of species richness, consequences for β-diversity, changes in community composition between sites, are largely unknown, especially in the tropics. Using a 10-year data set on Costa Rican birds, we find that low-intensity agriculture sustained β-diversity across large scales on a par with forest. In high-intensity agriculture, low local (α) diversity inflated β-diversity as a statistical artefact. Therefore, at small spatial scales, intensive agriculture appeared to retain β-diversity. Unlike in forest or low-intensity systems, however, high-intensity agriculture also homogenised vegetation structure over large distances, thereby decoupling the fundamental ecological pattern of bird communities changing with geographical distance. This ~40% decline in species turnover indicates a significant decline in β-diversity at large spatial scales. These findings point the way towards multi-functional agricultural systems that maintain agricultural productivity while simultaneously conserving biodiversity.

    View details for DOI 10.1111/j.1461-0248.2012.01815.x

    View details for Web of Science ID 000306475600005

    View details for PubMedID 22727063

  • Improving estimates of biodiversity loss BIOLOGICAL CONSERVATION Mendenhall, C. D., Daily, G. C., Ehrlich, P. R. 2012; 151 (1): 32-34
  • Securing natural capital and expanding equity to rescale civilization NATURE Ehrlich, P. R., Kareiva, P. M., Daily, G. C. 2012; 486 (7401): 68-73

    Abstract

    In biophysical terms, humanity has never been moving faster nor further from sustainability than it is now. Our increasing population size and per capita impacts are severely testing the ability of Earth to provide for peoples' most basic needs. Awareness of these circumstances has grown tremendously, as has the sophistication of efforts to address them. But the complexity of the challenge remains daunting. We explore prospects for transformative change in three critical areas of sustainable development: achieving a sustainable population size and securing vital natural capital, both in part through reducing inequity, and strengthening the societal leadership of academia.

    View details for DOI 10.1038/nature11157

    View details for Web of Science ID 000304854000028

    View details for PubMedID 22678281

  • Human behavior and sustainability FRONTIERS IN ECOLOGY AND THE ENVIRONMENT Fischer, J., Dyball, R., Fazey, I., Gross, C., Dovers, S., Ehrlich, P. R., Brulle, R. J., Christensen, C., Borden, R. J. 2012; 10 (3): 153-160

    View details for DOI 10.1890/110079

    View details for Web of Science ID 000302441000020

  • Reservoirs of richness: least disturbed tropical forests are centres of undescribed species diversity PROCEEDINGS OF THE ROYAL SOCIETY B-BIOLOGICAL SCIENCES Giam, X., Scheffers, B. R., Sodhi, N. S., Wilcove, D. S., Ceballos, G., Ehrlich, P. R. 2012; 279 (1726): 67-76

    Abstract

    In the last few decades, there has been a remarkable discovery of new species of plants, invertebrates and vertebrates, in what have been called the new age of discovery. However, owing to anthropogenic impacts such as habitat conversion, many of the still unknown species may go extinct before being scientifically documented (i.e. 'crypto-extinctions'). Here, by applying a mathematical model of species descriptions which accounts for taxonomic effort, we show that even after 250 years of taxonomic classification, about 3050 amphibians and at least 160 land mammal species remain to be discovered and described. These values represent, respectively, 33 and 3 per cent of the current species total for amphibians and land mammals. We found that tropical moist forests of the Neotropics, Afrotropics and Indomalaya probably harbour the greatest numbers of undescribed species. Tropical forests with minimal anthropogenic disturbance are predicted to have larger proportions of undescribed species. However, the protected area coverage is low in many of these key biomes. Moreover, undescribed species are likely to be at a greater risk of extinction compared with known species because of small geographical ranges among other factors. By highlighting the key areas of undescribed species diversity, our study provides a starting template to rapidly document these species and protect them through better habitat management.

    View details for DOI 10.1098/rspb.2011.0433

    View details for Web of Science ID 000297674300010

    View details for PubMedID 21593037

    View details for PubMedCentralID PMC3223638

  • Resilience and stability in bird guilds across tropical countryside PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA Karp, D. S., Ziv, G., Zook, J., Ehrlich, P. R., Daily, G. C. 2011; 108 (52): 21134-21139

    Abstract

    The consequences of biodiversity decline in intensified agricultural landscapes hinge on surviving biotic assemblages. Maintaining crucial ecosystem processes and services requires resilience to natural and anthropogenic disturbances. However, the resilience and stability of surviving biological communities remain poorly quantified. From a 10-y dataset comprising 2,880 bird censuses across a land-use gradient, we present three key findings concerning the resilience and stability of Costa Rican bird communities. First, seed dispersing, insect eating, and pollinating guilds were more resilient to low-intensity land use than high-intensity land use. Compared with forest assemblages, bird abundance, species richness, and diversity were all ~15% lower in low-intensity land use and ~50% lower in high-intensity land use. Second, patterns in species richness generally correlated with patterns in stability: guilds exhibited less variation in abundance in low-intensity land use than in high-intensity land use. Finally, interspecific differences in reaction to environmental change (response diversity) and possibly the portfolio effect, but not negative covariance of species abundances, conferred resilience and stability. These findings point to the changes needed in agricultural production practices in the tropics to better sustain bird communities and, possibly, the functional and service roles that they play.

    View details for DOI 10.1073/pnas.1118276108

    View details for Web of Science ID 000298479900055

    View details for PubMedID 22160726

    View details for PubMedCentralID PMC3248489

  • Homage to an Avant-Garde Conservation Leader, Navjot Sodhi Obituary CONSERVATION BIOLOGY Bradshaw, C. J., Laurance, W. F., Gibson, L., Ehrlich, P. R., Brook, B. W. 2011; 25 (5): 1056-1058
  • Predictive model for sustaining biodiversity in tropical countryside PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA Mendenhall, C. D., Sekercioglu, C. H., Brenes, F. O., Ehrlich, P. R., Daily, G. C. 2011; 108 (39): 16313-16316

    Abstract

    Growing demand for food, fuel, and fiber is driving the intensification and expansion of agricultural land through a corresponding displacement of native woodland, savanna, and shrubland. In the wake of this displacement, it is clear that farmland can support biodiversity through preservation of important ecosystem elements at a fine scale. However, how much biodiversity can be sustained and with what tradeoffs for production are open questions. Using a well-studied tropical ecosystem in Costa Rica, we develop an empirically based model for quantifying the "wildlife-friendliness" of farmland for native birds. Some 80% of the 166 mist-netted species depend on fine-scale countryside forest elements (≤ 60-m-wide clusters of trees, typically of variable length and width) that weave through farmland along hilltops, valleys, rivers, roads, and property borders. Our model predicts with ∼75% accuracy the bird community composition of any part of the landscape. We find conservation value in small (≤ 20 m wide) clusters of trees and somewhat larger (≤ 60 m wide) forest remnants to provide substantial support for biodiversity beyond the borders of tropical forest reserves. Within the study area, forest elements on farms nearly double the effective size of the local forest reserve, providing seminatural habitats for bird species typically associated with the forest. Our findings provide a basis for estimating and sustaining biodiversity in farming systems through managing fine-scale ecosystem elements and, more broadly, informing ecosystem service analyses, biodiversity action plans, and regional land use strategies.

    View details for DOI 10.1073/pnas.1111687108

    View details for Web of Science ID 000295255300040

    View details for PubMedID 21911396

    View details for PubMedCentralID PMC3182680

  • Global distribution and conservation of marine mammals PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA Pompa, S., Ehrlich, P. R., Ceballos, G. 2011; 108 (33): 13600-13605

    Abstract

    We identified 20 global key conservation sites for all marine (123) and freshwater (6) mammal species based on their geographic ranges. We created geographic range maps for all 129 species and a Geographic Information System database for a 46,184 1° x 1° grid-cells, ∼10,000-km(2). Patterns of species richness, endemism, and risk were variable among all species and species groups. Interestingly, marine mammal species richness was correlated strongly with areas of human impact across the oceans. Key conservation sites in the global geographic grid were determined either by their species richness or by their irreplaceability or uniqueness, because of the presence of endemic species. Nine key conservation sites, comprising the 2.5% of the grid cells with the highest species richness, were found, mostly in temperate latitudes, and hold 84% of marine mammal species. In addition, we identified 11 irreplaceable key conservation sites, six of which were found in freshwater bodies and five in marine regions. These key conservation sites represent critical areas of conservation value at a global level and can serve as a first step for adopting global strategies with explicit geographic conservation targets for Marine Protected Areas.

    View details for DOI 10.1073/pnas.1101525108

    View details for Web of Science ID 000293895100051

    View details for PubMedID 21808012

    View details for PubMedCentralID PMC3158205

  • Intervention Ecology: Applying Ecological Science in the Twenty-first Century BIOSCIENCE Hobbs, R. J., Hallett, L. M., Ehrlich, P. R., Mooney, H. A. 2011; 61 (6): 442-450
  • Population decline assessment, historical baselines, and conservation CONSERVATION LETTERS Bonebrake, T. C., Christensen, J., Boggs, C. L., Ehrlich, P. R. 2010; 3 (6): 371-378
  • Retrospective. Stephen Schneider (1945-2010). Science Ehrlich, P. R. 2010; 329 (5993): 776-?

    View details for DOI 10.1126/science.1195502

    View details for PubMedID 20705843

  • More than just indicators: A review of tropical butterfly ecology and conservation BIOLOGICAL CONSERVATION Bonebrake, T. C., Ponisio, L. C., Boggs, C. L., Ehrlich, P. R. 2010; 143 (8): 1831-1841
  • Oviposition behavior and offspring performance in herbivorous insects: consequences of climatic and habitat heterogeneity OIKOS Bonebrake, T. C., Boggs, C. L., McNally, J. M., Ranganathan, J., Ehrlich, P. R. 2010; 119 (6): 927-934
  • Biological collections and ecological/environmental research: a review, some observations and a look to the future BIOLOGICAL REVIEWS Pyke, G. H., Ehrlich, P. R. 2010; 85 (2): 247-266

    Abstract

    Housed worldwide, mostly in museums and herbaria, is a vast collection of biological specimens developed over centuries. These biological collections, and associated taxonomic and systematic research, have received considerable long-term public support. The work remaining in systematics has been expanding as the estimated total number of species of organisms on Earth has risen over recent decades, as have estimated numbers of undescribed species. Despite this increasing task, support for taxonomic and systematic research, and biological collections upon which such research is based, has declined over the last 30-40 years, while other areas of biological research have grown considerably, especially those that focus on environmental issues. Reflecting increases in research that deals with ecological questions (e.g. what determines species distribution and abundance) or environmental issues (e.g. toxic pollution), the level of research attempting to use biological collections in museums or herbaria in an ecological/environmental context has risen dramatically during about the last 20 years. The perceived relevance of biological collections, and hence the support they receive, should be enhanced if this trend continues and they are used prominently regarding such environmental issues as anthropogenic loss of biodiversity and associated ecosystem function, global climate change, and decay of the epidemiological environment. It is unclear, however, how best to use biological collections in the context of such ecological/environmental issues or how best to manage collections to facilitate such use. We demonstrate considerable and increasingly realized potential for research based on biological collections to contribute to ecological/environmental understanding. However, because biological collections were not originally intended for use regarding such issues and have inherent biases and limitations, they are proving more useful in some contexts than in others. Biological collections have, for example, been particularly useful as sources of information regarding variation in attributes of individuals (e.g. morphology, chemical composition) in relation to environmental variables, and provided important information in relation to species' distributions, but less useful in the contexts of habitat associations and population sizes. Changes to policies, strategies and procedures associated with biological collections could mitigate these biases and limitations, and hence make such collections more useful in the context of ecological/environmental issues. Haphazard and opportunistic collecting could be replaced with strategies for adding to existing collections that prioritize projects that use biological collections and include, besides taxonomy and systematics, a focus on significant environmental/ecological issues. Other potential changes include increased recording of the nature and extent of collecting effort and information associated with each specimen such as nearby habitat and other individuals observed but not collected. Such changes have begun to occur within some institutions. Institutions that house biological collections should, we think, pursue a mission of 'understanding the life of the planet to inform its stewardship' (Krishtalka & Humphrey, 2000), as such a mission would facilitate increased use of biological collections in an ecological/environmental context and hence lead to increased appreciation, encouragement and support from the public for these collections, their associated research, and the institutions that house them.

    View details for DOI 10.1111/j.1469-185X.2009.00098.x

    View details for Web of Science ID 000276602200003

    View details for PubMedID 19961469

  • The MAHB, the Culture Gap, and Some Really Inconvenient Truths PLOS BIOLOGY Ehrlich, P. R. 2010; 8 (4)

    View details for DOI 10.1371/journal.pbio.1000330

    View details for PubMedID 20386722

  • Local people value environmental services provided by forested parks BIODIVERSITY AND CONSERVATION Sodhi, N. S., Lee, T. M., Sekercioglu, C. H., Webb, E. L., Prawiradilaga, D. M., Lohman, D. J., Pierce, N. E., Diesmos, A. C., Rao, M., Ehrlich, P. R. 2010; 19 (4): 1175-1188
  • Ecoethics: Now Central to All Ethics JOURNAL OF BIOETHICAL INQUIRY Ehrlich, P. R. 2009; 6 (4): 417-436
  • Inferring population histories using cultural data PROCEEDINGS OF THE ROYAL SOCIETY B-BIOLOGICAL SCIENCES Rogers, D. S., Feldman, M. W., Ehrlich, P. R. 2009; 276 (1674): 3835-3843

    Abstract

    The question as to whether cultures evolve in a manner analogous to that of genetic evolution can be addressed by attempting to reconstruct population histories using cultural data. As others have argued, this can only succeed if cultures are isolated enough to maintain and pass on a central core of traditions that can be modified over time. In this study we used a set of cultural data (canoe design traits from Polynesia) to look for the kinds of patterns and relationships normally found in population genetic studies. After developing new techniques to accommodate the peculiarities of cultural data, we were able to infer an ancestral region (Fiji) and a sequence of cultural origins for these Polynesian societies. In addition, we found evidence of cultural exchange, migration and a serial founder effect. Results were stronger when analyses were based on functional traits (presumably subject to natural selection and convergence) rather than symbolic or stylistic traits (probably subject to cultural selection for rapid divergence). These patterns strongly suggest that cultural evolution, while clearly affected by cultural exchange, is also subject to some of the same processes and constraints as genetic evolution.

    View details for DOI 10.1098/rspb.2009.1088

    View details for Web of Science ID 000270174800013

    View details for PubMedID 19675007

    View details for PubMedCentralID PMC2817289

  • 7 billon and counting ... NEW SCIENTIST Ehrlich, P., Ehrlich, A. 2009; 203 (2727): 34-37
  • Cultural evolution and the human predicament TRENDS IN ECOLOGY & EVOLUTION Ehrlich, P. R. 2009; 24 (8): 409-412

    Abstract

    For decades, scientists have been calling for action to halt environmental degradation, and there has been a substantial (but variable) response from the ecological and evolutionary research communities. Nonetheless, the degradation continues more rapidly than ever, by almost any biophysical measure. Here I briefly summarize and frame the situation, and suggest some major research thrusts for our community to accelerate the needed cultural responses, given that accumulating human impacts could threaten the collapse of global civilization.

    View details for DOI 10.1016/j.tree.2009.03.015

    View details for Web of Science ID 000269051400001

    View details for PubMedID 19577322

  • Discoveries of new mammal species and their implications for conservation and ecosystem services PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA Ceballos, G., Ehrlich, P. R. 2009; 106 (10): 3841-3846

    Abstract

    In light of recent discoveries of many new species of poorly-studied organisms, we examine the biodiversity of mammals, a well known "charismatic" group. Many assume that nearly all mammal species are known to scientists. We demonstrate that this assumption is incorrect. Since 1993, 408 new mammalian species have been described, approximately 10% of the previously known fauna. Some 60% of these are "cryptic" species, but 40% are large and distinctive. A substantial number persist only in areas undergoing rapid habitat destruction. Our findings suggest global animal and plant species diversity is badly underestimated even in well studied taxa. This implies even greater threats to ecosystem services and human well-being than previously assumed, and an increased need to explore, understand, and conserve Earth's living resources.

    View details for DOI 10.1073/pnas.0812419106

    View details for Web of Science ID 000264036900037

    View details for PubMedID 19228946

    View details for PubMedCentralID PMC2656167

  • Diversity in Current Ecological Thinking: Implications for Environmental Management ENVIRONMENTAL MANAGEMENT Moore, S. A., Wallington, T. J., Hobbs, R. J., Ehrlich, P. R., Holling, C. S., Levin, S., Lindenmayer, D., Pahl-Wostl, C., Possingham, H., Turner, M. G., Westoby, M. 2009; 43 (1): 17-27

    Abstract

    Current ecological thinking emphasizes that systems are complex, dynamic, and unpredictable across space and time. What is the diversity in interpretation of these ideas among today's ecologists, and what does this mean for environmental management? This study used a Policy Delphi survey of ecologists to explore their perspectives on a number of current topics in ecology. The results showed general concurrence with nonequilibrium views. There was agreement that disturbance is a widespread, normal feature of ecosystems with historically contingent responses. The importance of recognizing multiple levels of organization and the role of functional diversity in environmental change were also widely acknowledged. Views differed regarding the predictability of successional development, whether "patchiness" is a useful concept, and the benefits of shifting the focus from species to ecosystem processes. Because of their centrality to environmental management, these different views warrant special attention from both managers and ecologists. Such divergence is particularly problematic given widespread concerns regarding the poor linkages between science (here, ecology) and environmental policy and management, which have been attributed to scientific uncertainty and a lack of consensus among scientists, both jeopardizing the transfer of science into management. Several suggestions to help managers deal with these differences are provided, especially the need to interpret broader theory in the context of place-based assessments. The uncertainty created by these differences requires a proactive approach to environmental management, including clearly identifying environmental objectives, careful experimental design, and effective monitoring.

    View details for DOI 10.1007/s00267-008-9187-2

    View details for Web of Science ID 000261762900002

    View details for PubMedID 18709471

  • Sustaining biodiversity in ancient tropical countryside PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA Ranganathan, J., Daniels, R. J., Chandran, M. D., Ehrlich, P. R., Daily, G. C. 2008; 105 (46): 17852-17854

    Abstract

    With intensifying demands for food and biofuels, a critical threat to biodiversity is agricultural expansion into native tropical ecosystems. Tropical agriculture, particularly intensive agriculture, often supports few native organisms, and consequently has been largely overlooked in conservation planning; yet, recent work in the Neotropics demonstrates that tropical agriculture with certain features can support significant biodiversity, decades after conversion to farmland. It remains unknown whether this conservation value can be sustained for centuries to millennia. Here, we quantify the bird diversity affiliated with agricultural systems in southwest India, a region continuously cultivated for >2,000 years. We show that arecanut palm (Areca catechu) production systems retain 90% of the bird species associated with regional native forest. Two factors promote this high conservation value. First, the system involves intercropping with multiple, usually woody, understory species and, thus, has high vertical structural complexity that is positively correlated with bird species richness. Second, the system encompasses nearby forests, where large quantities of leaf litter are extracted for mulch. The preservation of these forests on productive land traces back to their value in supplying inputs to arecanut cultivation. The long-term biodiversity value of an agricultural ecosystem has not been documented in South and Southeast Asia. Our findings open a new conservation opportunity for this imperiled region that may well extend to other crops. Some of these working lands may be able to sustain native species over long-time scales, indicating that conservation investments in agriculture today could pay off for people and for nature.

    View details for DOI 10.1073/pnas.0808874105

    View details for Web of Science ID 000261225600052

    View details for PubMedID 18981411

    View details for PubMedCentralID PMC2577706

  • Should agricultural policies encourage land sparing or wildlife-friendly farming? FRONTIERS IN ECOLOGY AND THE ENVIRONMENT Fischer, J., Brosi, B., Daily, G. C., Ehrlich, P. R., Goldman, R., Goldstein, J., Lindenmayer, D. B., Manning, A. D., Mooney, H. A., Pejchar, L., Ranganathan, J., Tallis, H. 2008; 6 (7): 382-387

    View details for DOI 10.1890/070019

    View details for Web of Science ID 000259308000020

  • Colloquium paper: where does biodiversity go from here? A grim business-as-usual forecast and a hopeful portfolio of partial solutions. Proceedings of the National Academy of Sciences of the United States of America Ehrlich, P. R., Pringle, R. M. 2008; 105: 11579-11586

    Abstract

    The threats to the future of biodiversity are many and well known. They include habitat conversion, environmental toxification, climate change, and direct exploitation of wildlife, among others. Moreover, the projected addition of 2.6 billion people by mid-century will almost certainly have a greater environmental impact than that of the last 2.6 billion. Collectively, these trends portend a grim future for biodiversity under a business-as-usual scenario. These threats and their interactions are formidable, but we review seven strategies that, if implemented soundly and scaled up dramatically, would preserve a substantial portion of global biodiversity. These are actions to stabilize the human population and reduce its material consumption, the deployment of endowment funds and other strategies to ensure the efficacy and permanence of conservation areas, steps to make human-dominated landscapes hospitable to biodiversity, measures to account for the economic costs of habitat degradation, the ecological reclamation of degraded lands and repatriation of extirpated species, the education and empowerment of people in the rural tropics, and the fundamental transformation of human attitudes about nature. Like the carbon "stabilization wedges" outlined by Pacala and Socolow [Pacala S, Socolow R (2004) Stabilization wedges: Solving the climate problem for the next 50 years with current technologies. Science 305:968-972] (1), the science and technologies needed to effect this vision already exist. The remaining challenges are largely social, political, and economic. Although academic conservation biology still has an important role to play in developing technical tools and knowledge, success at this juncture hinges more on a massive mobilization of effort to do things that have traditionally been outside the scope of the discipline.

    View details for DOI 10.1073/pnas.0801911105

    View details for PubMedID 18695214

    View details for PubMedCentralID PMC2556413

  • Where does biodiversity go from here? A grim business-as-usual forecast and a hopeful portfolio of partial solutions PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA Ehrlich, P. R., Pringle, R. M. 2008; 105: 11579-11586

    Abstract

    The threats to the future of biodiversity are many and well known. They include habitat conversion, environmental toxification, climate change, and direct exploitation of wildlife, among others. Moreover, the projected addition of 2.6 billion people by mid-century will almost certainly have a greater environmental impact than that of the last 2.6 billion. Collectively, these trends portend a grim future for biodiversity under a business-as-usual scenario. These threats and their interactions are formidable, but we review seven strategies that, if implemented soundly and scaled up dramatically, would preserve a substantial portion of global biodiversity. These are actions to stabilize the human population and reduce its material consumption, the deployment of endowment funds and other strategies to ensure the efficacy and permanence of conservation areas, steps to make human-dominated landscapes hospitable to biodiversity, measures to account for the economic costs of habitat degradation, the ecological reclamation of degraded lands and repatriation of extirpated species, the education and empowerment of people in the rural tropics, and the fundamental transformation of human attitudes about nature. Like the carbon "stabilization wedges" outlined by Pacala and Socolow [Pacala S, Socolow R (2004) Stabilization wedges: Solving the climate problem for the next 50 years with current technologies. Science 305:968-972] (1), the science and technologies needed to effect this vision already exist. The remaining challenges are largely social, political, and economic. Although academic conservation biology still has an important role to play in developing technical tools and knowledge, success at this juncture hinges more on a massive mobilization of effort to do things that have traditionally been outside the scope of the discipline.

    View details for DOI 10.1073/pnas.0801911105

    View details for Web of Science ID 000258561200018

    View details for PubMedCentralID PMC2556413

  • Population, environment, war, and racism: Adventures of a public scholar ANTIPODE Ehrlich, P. R. 2008; 40 (3): 383-388
  • Diversity, natural history and conservation of amphibians and reptiles from the San Vito Region, southwestern Costa Rica REVISTA DE BIOLOGIA TROPICAL Santos-Barrera, G., Pacheco, J., Mendoza-Quijano, F., Bolanos, F., Chaves, G., Daily, G. C., Ehrlich, P. R., Ceballos, G. 2008; 56 (2): 755-778

    Abstract

    We present an inventory of the amphibians and reptiles of the San Vito de Coto Brus region, including the Las Cruces Biological Station, in southern Costa Rica, which is the result of a survey of the herpetofauna occurring in mountain forest fragments, pastures, coffee plantations, and other disturbed areas. We found 67 species, included 26 species of amphibians and of 41 of reptiles. We describe the distribution patterns of the community on the basis of the life zones, elevation, fragmentation, and degree of anthropogenic impact. We also provide some nouvelle data on the systematics of some select taxa, their geographical ranges, microhabitats, activity, and other relevant ecological and natural history features. Finally, we comment on the present conservation status of the herpetofauna in the region. Previous literature and collection records indicate a higher number of species occurring in this area, which suggests that some declines have occurred, especially of amphibians, in last decades.

    View details for Web of Science ID 000259618700027

    View details for PubMedID 19256442

  • Natural selection and cultural rates of change PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA Rogers, D. S., Ehrlich, P. R. 2008; 105 (9): 3416-3420

    Abstract

    It has been claimed that a meaningful theory of cultural evolution is not possible because human beliefs and behaviors do not follow predictable patterns. However, theoretical models of cultural transmission and observations of the development of societies suggest that patterns in cultural evolution do occur. Here, we analyze whether two sets of related cultural traits, one tested against the environment and the other not, evolve at different rates in the same populations. Using functional and symbolic design features for Polynesian canoes, we show that natural selection apparently slows the evolution of functional structures, whereas symbolic designs differentiate more rapidly. This finding indicates that cultural change, like genetic evolution, can follow theoretically derived patterns.

    View details for DOI 10.1073/pnas.0711802105

    View details for Web of Science ID 000253846500044

    View details for PubMedID 18287028

    View details for PubMedCentralID PMC2265130

  • Demography and policy: A view from outside the discipline POPULATION AND DEVELOPMENT REVIEW Ehrlich, P. R. 2008; 34 (1): 103-?
  • Key issues for attention from ecological economists ENVIRONMENT AND DEVELOPMENT ECONOMICS Ehrlich, P. R. 2008; 13: 1-20
  • Nature's economy and the human economy ENVIRONMENTAL & RESOURCE ECONOMICS Ehrlich, P. R., Ehrlich, A. H. 2008; 39 (1): 9-16
  • Is current consumption excessive? A general framework and some indications for the United States CONSERVATION BIOLOGY Ehrlich, P. R., Goulder, L. H. 2007; 21 (5): 1145-1154

    Abstract

    Many prior studies have explored the implications of human population growth and environmentally problematic technologies for biodiversity loss and other forms of environmental degradation. Relatively few, however, have examined the impacts of the level and composition of consumption. We offer a framework that shows how the level and composition of a society's total consumption relate to the uses of various forms of capital and to the sustainability of natural resources and human well-being. We relate the framework to two main approaches-top-down macro studies and bottom-up computer models-for measuring whether overall consumption in the United States satisfies a sustainability requirement. Existing top-down studies have shortcomings that bias their results toward optimism, and current computer simulation models, although strong on revealing biophysical outcomes, are limited in their ability to evaluate impacts on human well-being. Although some ambiguities arise in determining whether overall consumption in the United States is excessive, our conclusions regarding the composition of U.S. consumption are unambiguous. Distorted consumption patterns and associated production methods lead to excessively rapid natural resource depletion; greater conservation would yield gains to current and future generations that more than compensate for the sacrifices involved. Public policies that deal with the composition problem not only would help conserve natural resources and improve current welfare but also would reduce the costs of meeting the goal of sustainability.

    View details for DOI 10.1111/j.1523-1739.2007-00779.x

    View details for Web of Science ID 000250008700006

    View details for PubMedID 17883480

  • Persistence of forest birds in the Costa Rican agricultural countryside CONSERVATION BIOLOGY Sekercioglu, C. H., Loarie, S. R., Brenes, F. O., Ehrlich, P. R., Daily, G. C. 2007; 21 (2): 482-494

    Abstract

    Understanding the persistence mechanisms of tropical forest species in human-dominated landscapes is a fundamental challenge of tropical ecology and conservation. Many species, including more than half of Costa Rica's native land birds, use mostly deforested agricultural countryside, but how they do so is poorly known. Do they commute regularly to forest or can some species survive in this human-dominated landscape year-round? Using radiotelemetry, we detailed the habitat use, movement, foraging, and nesting patterns of three bird species, Catharus aurantiirostris, Tangara icterocephala, and Turdus assimilis, by obtaining 8101 locations from 156 individuals. We chose forest birds that varied in their vulnerability to deforestation and were representative of the species found both in forest and human-dominated landscapes. Our study species did not commute from extensive forest; rather, they fed and bred in the agricultural countryside. Nevertheless, T. icterocephala and T. assimilis, which are more habitat sensitive, were highly dependent on the remaining trees. Although trees constituted only 11% of land cover, these birds spent 69% to 85% of their time in them. Breeding success of C. aurntiirostris and T. icterocephala in deforested habitats was not different than in forest remnants, where T. assimilis experienced reduced breeding success. Although this suggests an ecological trap for T. assimilis, higher fledgling survival in forest remnants may make up for lower productivity. Tropical countryside has high potential conservation value, which can be enhanced with even modest increases in tree cover. Our findings have applicability to many human-dominated tropical areas that have the potential to conserve substantial biodiversity if appropriate restoration measures are taken.

    View details for DOI 10.1111/j.1523-1739.2007.00655.x

    View details for Web of Science ID 000245438200024

    View details for PubMedID 17391198

  • Bee community shifts with landscape context in a tropical countryside ECOLOGICAL APPLICATIONS Brosi, B. J., Daily, G. C., Ehrlich, P. R. 2007; 17 (2): 418-430

    Abstract

    The ongoing scientific controversy over a putative "global pollination crisis" underscores the lack of understanding of the response of bees (the most important taxon of pollinators) to ongoing global land-use changes. We studied the effects of distance to forest, tree management, and floral resources on bee communities in pastures (the dominant land-use type) in southern Costa Rica. Over two years, we sampled bees and floral resources in 21 pastures at three distance classes from a large (approximately 230-ha) forest patch and of three common types: open pasture; pasture with remnant trees; and pasture with live fences. We found no consistent differences in bee diversity or abundance with respect to pasture management or floral resources. Bee community composition, however, was strikingly different at forest edges as compared to deforested countryside only a few hundred meters from forest. At forest edges, native social stingless bees (Apidae: Meliponini) comprised approximately 50% of the individuals sampled, while the alien honeybee Apis mellifera made up only approximately 5%. Away from forests, meliponines dropped to approximately 20% of sampled bees, whereas Apis increased to approximately 45%. Meliponine bees were also more speciose at forest edge sites than at a distance from forest, their abundance decreased with continuous distance to the nearest forest patch, and their species richness was correlated with the proportion of forest cover surrounding sample sites at scales from 200 to 1200 m. Meliponines and Apis together comprise the eusocial bee fauna of the study area and are unique in quickly recruiting foragers to high-quality resources. The diverse assemblage of native meliponine bees covers a wide range of body sizes and flower foraging behavior not found in Apis, and populations of many bee species (including Apis), are known to fluctuate considerably from year to year. Thus, the forest-related changes in eusocial bee communities we found may have important implications for: (1) sustaining a diverse bee fauna in tropical countryside; (2) ensuring the effective pollination of a diverse native plant community; and (3) the efficiency and stability of agricultural pollination, particularly for short-time-scale, mass-flowering crops such as coffee.

    View details for Web of Science ID 000245744200011

    View details for PubMedID 17489249

  • When agendas collide: Human welfare and biological conservation CONSERVATION BIOLOGY Chan, K. M., Pringle, R. M., Ranganathan, J., Boggs, C. L., Chan, Y. L., Ehrlich, P. R., Haff, P. K., Heller, N. E., Al-Krafaji, K., Macmynowski, D. P. 2007; 21 (1): 59-68

    Abstract

    Conservation should benefit ecosystems, nonhuman organisms, and current and future human beings. Nevertheless, tension among these goals engenders potential ethical conflicts: conservationists' true motivations may differ from the justifications they offer for their activities, and conservation projects have the potential to disempower and oppress people. We reviewed the promise and deficiencies of integrating social, economic, and biological concerns into conservation, focusing on research in ecosystem services and efforts in community-based conservation. Despite much progress, neither paradigm provides a silver bullet for conservation's most pressing problems, and both require additional thought and modification to become maximally effective. We conclude that the following strategies are needed to make conservation more effective in our human-dominated world. (1) Conservation research needs to integrate with social scholarship in a more sophisticated manner. (2) Conservation must be informed by a detailed understanding of the spatial, temporal, and social distributions of costs and benefits of conservation efforts. Strategies should reflect this understanding, particularly by equitably distributing conservation's costs. (3) We must better acknowledge the social concerns that accompany biodiversity conservation; accordingly, sometimes we must argue for conservation for biodiversity's sake, not for its direct human benefits.

    View details for DOI 10.1111/j.1523-1739.2006.00570.x

    View details for Web of Science ID 000244148800014

    View details for PubMedID 17298511

  • Global mammal distributions, biodiversity hotspots, and conservation PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA Ceballos, G., Ehrlich, P. R. 2006; 103 (51): 19374-19379

    Abstract

    Hotspots, which have played a central role in the selection of sites for reserves, require careful rethinking. We carried out a global examination of distributions of all nonmarine mammals to determine patterns of species richness, endemism, and endangerment, and to evaluate the degree of congruence among hotspots of these three measures of diversity in mammals. We then compare congruence of hotspots in two animal groups (mammals and birds) to assess the generality of these patterns. We defined hotspots as the richest 2.5% of cells in a global equal-area grid comparable to 1 degrees latitude x 1 degrees longitude. Hotspots of species richness, "endemism," and extinction threat were noncongruent. Only 1% of cells and 16% of species were common to the three types of mammalian hotspots. Congruence increased with increases in both the geographic scope of the analysis and the percentage of cells defined as being hotspots. The within-mammal hotspot noncongruence was similar to the pattern recently found for birds. Thus, assigning global conservation priorities based on hotspots is at best a limited strategy.

    View details for DOI 10.1073/pnas.0609334103

    View details for Web of Science ID 000243166600029

    View details for PubMedID 17164331

    View details for PubMedCentralID PMC1698439

  • Environmental science input to public policy SOCIAL RESEARCH Ehrlich, P. R. 2006; 73 (3): 915-948
  • Enough already NEW SCIENTIST Ehrlich, P., Ehrlich, A. 2006; 191 (2571): 46-50
  • Delayed population explosion of an introduced butterfly JOURNAL OF ANIMAL ECOLOGY Boggs, C. L., Holdren, C. E., Kulahci, I. G., Bonebrake, T. C., Inouye, B. D., Fay, J. P., McMillan, A., Williams, E. H., Ehrlich, P. R. 2006; 75 (2): 466-475

    Abstract

    1. The causes of lagged population and geographical range expansions after species introductions are poorly understood, and there are relatively few detailed case studies. 2. We document the 29-year history of population dynamics and structure for a population of Euphydryas gillettii Barnes that was introduced to the Colorado Rocky Mountains, USA in 1977. 3. The population size remained low (< 200 individuals) and confined to a single habitat patch (approximately 2.25 ha) to 1998. These values are similar to those of many other populations within the natural geographical range of the species. 4. However, by 2002 the population increased dramatically to > 3000 individuals and covered approximately 70 ha, nearly all to the south of the original site. The direction of population expansion was the same as that of predominant winds. 5. By 2004, the butterfly's local distribution had retracted mainly to three habitat patches. It thus exhibited a 'surge/contraction' form of population growth. Searches within 15 km of the original site yielded no other new populations. 6. In 2005, butterfly numbers crashed, but all three habitat patches remained occupied. The populations within each patch did not decrease in the same proportions, suggesting independent dynamics that are characteristic of metapopulations. 7. We postulate that this behaviour results, in this species, in establishment of satellite populations and, given appropriate habitat structure, may result in lagged or punctuated expansions of introduced populations.

    View details for DOI 10.1111/j.1365-2656.2006.01067.x

    View details for Web of Science ID 000236384700015

    View details for PubMedID 16637999

  • Sustainability. Millennium assessment of human behavior. Science Ehrlich, P. R., Kennedy, D. 2005; 309 (5734): 562-563

    View details for PubMedID 16040693

  • The evolution of norms PLOS BIOLOGY Ehrlich, P. R., Levin, S. A. 2005; 3 (6): 943-948

    View details for DOI 10.1371/journal.pbio.0030194

    View details for Web of Science ID 000229992900001

    View details for PubMedID 15941355

    View details for PubMedCentralID PMC1149491

  • Ecosystem consequences of bird declines PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA Sekercioglu, C. H., Daily, G. C., Ehrlich, P. R. 2004; 101 (52): 18042-18047

    Abstract

    We present a general framework for characterizing the ecological and societal consequences of biodiversity loss and applying it to the global avifauna. To investigate the potential ecological consequences of avian declines, we developed comprehensive databases of the status and functional roles of birds and a stochastic model for forecasting change. Overall, 21% of bird species are currently extinction-prone and 6.5% are functionally extinct, contributing negligibly to ecosystem processes. We show that a quarter or more of frugivorous and omnivorous species and one-third or more of herbivorous, piscivorous, and scavenger species are extinction-prone. Furthermore, our projections indicate that by 2100, 6-14% of all bird species will be extinct, and 7-25% (28-56% on oceanic islands) will be functionally extinct. Important ecosystem processes, particularly decomposition, pollination, and seed dispersal, will likely decline as a result.

    View details for DOI 10.1073/pnas.0408049101

    View details for Web of Science ID 000226102700030

    View details for PubMedID 15601765

    View details for PubMedCentralID PMC539768

  • Coping with uncertainty: A call for a new science-policy forum AMBIO Kinzig, A. P., Starrett, D., Arrow, K., Aniyar, S., Bolin, B., Dasgupta, P., Ehrlich, P., Folke, C., Hanemann, M., Heal, G., Hoel, M., Jansson, A., Jansson, B. O., Kautsky, N., Levin, S., Lubchenco, J., Maler, K. G., Pacala, S. W., Schneider, S. H., Siniscalco, D., Walker, B. 2003; 32 (5): 330-335

    Abstract

    The scientific and policy worlds have different goals, which can lead to different standards for what constitutes "proof" of a change or phenomena, and different approaches for characterizing and conveying uncertainty and risk. These differences can compromise effective communication among scientists, policymakers, and the public, and constrain the types of socially compelling questions scientists are willing to address. In this paper, we review a set of approaches for dealing with uncertainty, and illustrate some of the errors that arise when science and policy fail to coordinate correctly. We offer a set of recommendations, including restructuring of science curricula and establishment of science-policy forums populated by leaders in both arenas, and specifically constituted to address problems of uncertainty.

    View details for Web of Science ID 000185431000002

    View details for PubMedID 14571961

  • Some roots of terrorism POPULATION AND ENVIRONMENT Ehrlich, P. R., Liu, J. G. 2002; 24 (2): 183-192
  • Disappearance of insectivorous birds from tropical forest fragments PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA Sekercioglu, C. H., Ehrlich, P. R., Daily, G. C., Aygen, D., Goehring, D., Sandi, R. F. 2002; 99 (1): 263-267

    Abstract

    Determining the impact of forest disturbance and fragmentation on tropical biotas is a central goal of conservation biology. Among tropical forest birds, understory insectivores are particularly sensitive to habitat disturbance and fragmentation, despite their relatively small sizes and freedom from hunting pressure. Why these birds are especially vulnerable to fragmentation is not known. Our data indicate that the best determinant of the persistence of understory insectivorous birds in small fragments is the ability to disperse through deforested countryside habitats. This finding contradicts our initial hypothesis that the decline of insectivorous birds in forest fragments is caused by impoverished invertebrate prey base in fragments. Although we observed significantly fewer insectivorous birds in smaller fragments, extensive sampling of invertebrate communities (106,082 individuals) and avian diets (of 735 birds) revealed no important differences between large and small fragments. Neither habitat specificity nor drier fragment microclimates seemed critical. Bird species that were less affected by forest fragmentation were, in general, those that used the deforested countryside more, and we suggest that the key to their conservation will be found there.

    View details for Web of Science ID 000173233300049

    View details for PubMedID 11782549

  • Human natures, nature conservation, and environmental ethics BIOSCIENCE Ehrlich, P. R. 2002; 52 (1): 31-43
  • Intervening in evolution: Ethics and actions National-Academy-of-Sciences Colloquium on the Future of Evolution Ehrlich, P. R. NATL ACAD SCIENCES. 2001: 5477–80

    Abstract

    Biologists should help to guide a process of cultural evolution in which society determines how much effort, if any, is ethically required to preserve options in biological evolution. Evolutionists, conservation biologists, and ecologists should be doing more research to determine actions that would best help to avoid foreclosing evolutionary options.

    View details for Web of Science ID 000168623300021

    View details for PubMedID 11344297

    View details for PubMedCentralID PMC33237

  • Ecology - The value of nature and the nature of value SCIENCE Daily, G. C., Soderqvist, T., Aniyar, S., Arrow, K., Dasgupta, P., Ehrlich, P. R., Folke, C., Jansson, A., Jansson, B. O., Kautsky, N., Levin, S., Lubchenco, J., Maler, K. G., Simpson, D., Starrett, D., Tilman, D., Walker, B. 2000; 289 (5478): 395-396

    Abstract

    Ecosystems are capital assets: When properly managed, they yield a flow of vital goods and services. Relative to other forms of capital, however, ecosystems are poorly understood, scarcely monitored, and--in many important cases--undergoing rapid degradation. The process of economic valuation could greatly improve stewardship. This potential is now being realized with innovative financial instruments and institutional arrangements.

    View details for Web of Science ID 000088305500022

    View details for PubMedID 10939949

  • Economic incentives for rain forest conservation across scales SCIENCE Kremen, C., Niles, J. O., Dalton, M. G., Daily, G. C., Ehrlich, P. R., Fay, J. P., Grewal, D., Guillery, R. P. 2000; 288 (5472): 1828-1832

    Abstract

    Globally, tropical deforestation releases 20 to 30% of anthropogenic greenhouse gases. Conserving forests could reduce emissions, but the cost-effectiveness of this mechanism for mitigation depends on the associated opportunity costs. We estimated these costs from local, national, and global perspectives using a case study from Madagascar. Conservation generated significant benefits over logging and agriculture locally and globally. Nationally, however, financial benefits from industrial logging were larger than conservation benefits. Such differing economic signals across scales may exacerbate tropical deforestation. The Kyoto Protocol could potentially overcome this obstacle to conservation by creating markets for protection of tropical forests to mitigate climate change.

    View details for Web of Science ID 000087503800051

    View details for PubMedID 10846165

  • Donald Kennedy - The next Editor-in-Chief of Science SCIENCE Ehrlich, P. R. 2000; 288 (5470): 1349-1349

    View details for Web of Science ID 000087270900027

    View details for PubMedID 10847848

  • Food production, population growth, and the environment. Science Daily, G., Dasgupta, P., Bolin, B., Crosson, P., du Guerny, J., Ehrlich, P., Folke, C., Jansson, A. M., Jansson, B., Kautsky, N., Kinzig, A., Levin, S., Mäler, K. G., Pinstrup-Andersen, P., Siniscalco, D., Walker, B. 1998; 281 (5381): 1291-1292

    View details for PubMedID 9735046

  • Population diversity: Its extent and extinction SCIENCE Hughes, J. B., Daily, G. C., Ehrlich, P. R. 1997; 278 (5338): 689-692

    Abstract

    Genetically distinct populations are an important component of biodiversity. This work estimates the number of populations per area of a sample of species from literature on population differentiation and the average range area of a species from a sample of distribution maps. This yields an estimate of about 220 populations per species, or 1.1 to 6.6 billion populations globally. Assuming that population extinction is a linear function of habitat loss, approximately 1800 populations per hour (16 million annually) are being destroyed in tropical forests alone.

    View details for Web of Science ID A1997YC32300055

    View details for PubMedID 9381179

  • Ehrlichs' fables TECHNOLOGY REVIEW Ehrlich, P. R., Ehrlich, H. 1997; 100 (1): 38-47
  • Nocturnality and species survival PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA Daily, G. C., Ehrlich, P. R. 1996; 93 (21): 11709-11712

    Abstract

    Surveys of butterfly and moth diversity in tropical forest fragments suggest that nocturnality confers a dispersal, and possibly a survival, advantage. The butterfly faunas of smaller fragments were depauperate; in contrast, the species richness of nocturnal moths was similar in all fragments and even in pasture. The lack of correlation between butterfly and moth species richness among fragments (r2 = 0.005) is best explained by movements of moths at night when ambient conditions in forest and pasture are most similar; butterflies face substantial daytime temperature, humidity, and solar radiation barriers. This interpretation is supported by information on birds, beetles, and bats.

    View details for Web of Science ID A1996VM68100075

    View details for PubMedID 8876201

    View details for PubMedCentralID PMC38123

  • Environmental anti-science TRENDS IN ECOLOGY & EVOLUTION Ehrlich, P. R. 1996; 11 (9): 393-393

    View details for Web of Science ID A1996VC82300018

    View details for PubMedID 21237892

  • POPULATION AND IMMIGRATION POLICY IN THE UNITED-STATES - RESPONSE POPULATION AND ENVIRONMENT Daily, G. C., EHRLICH, A. H., Ehrlich, P. R. 1995; 16 (6): 521-526
  • OPTIMUM HUMAN-POPULATION SIZE POPULATION AND ENVIRONMENT Daily, G. C., EHRLICH, A. H., Ehrlich, P. R. 1994; 15 (6): 469-475
  • ENHANCING THE STATUS OF POPULATION BIOLOGY TRENDS IN ECOLOGY & EVOLUTION Ehrlich, P. R. 1994; 9 (4): 157-157

    View details for Web of Science ID A1994NB39500015

    View details for PubMedID 21236805

  • ECOLOGICAL ECONOMICS AND THE CARRYING-CAPACITY OF EARTH 1992 Wallenberg Workshop Ehrlich, P. R. ISLAND PRESS. 1994: 38–56
  • Influence of social status on individual foraging and community structure in a bird guild. Oecologia Daily, G. C., Ehrlich, P. R. 1994; 100 (1-2): 153–65

    Abstract

    We investigated the influence of social interactions on individual foraging behavior and community structure of frugivorous birds in southern Costa Rica. Detailed observations of large, heterospecific feeding assemblages at fruiting trees revealed the existence of an interspecific dominance hierarchy, largely consistent with body and bill size. Social status influenced access to food in several ways. First, subordinate species were interrupted more and tended to have shorter foraging bouts than dominant species (n > 1.000 abouts). Second, analysis of over 7,000 videotaped head movements showed that subordinate species spent a smaller fraction of their foraging bouts actually feeding (as opposed to looking about) than did dominants. Third, when many birds were in a tree simultaneously, the foraging bouts of subordinate species were shortened; this effect was less pronounced or absent for species higher in the dominance hierarchy. Fourth, subordinate species foraged less frequently in mixed-species assemblages than did dominant species. Finally, subordinate species fed disproportionately more in the late afternoon at fruiting trees. The influence of social status appeared to manifest itself at the community level. The species composition of foraging assemblages was compared at isolated fruiting trees situated in an agricultural landscape near to (< 0.5 km) and far from (> 6 km) a large tract of primary forest. Whereas the full complement of avian frugivores foraged at the near trees, visitors to the far trees were predominantly of high social status. We discuss reasons why high social status and associated traits might confer an advantage in exploiting human-dominated habitat.

    View details for PubMedID 28307039

  • DOUBLE KEYSTONE BIRD IN A KEYSTONE SPECIES COMPLEX PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA Daily, G. C., Ehrlich, P. R., Haddad, N. M. 1993; 90 (2): 592-594

    Abstract

    Species in a Colorado subalpine ecosystem show subtle interdependences. Red-naped sapsuckers play two distinct keystone roles. They excavate nest cavities in fungus-infected aspens that are required as nest sites by two species of swallows, and they drill sap wells into willows that provide abundant nourishment for themselves, hummingbirds, orange-crowned warblers, chipmunks, and an array of other sap robbers. The swallows thus depend on, and the sap robbers benefit from, a keystone species complex comprised of sapsuckers, willows, aspens, and a heartwood fungus. Disappearance of any element of the complex could cause an unanticipated unraveling of the community.

    View details for Web of Science ID A1993KH51600048

    View details for PubMedID 11607351

    View details for PubMedCentralID PMC45709

  • Adult emergence phenology in checkerspot butterflies: the effects of macroclimate, topoclimate, and population history. Oecologia Weiss, S. B., Murphy, D. D., Ehrlich, P. R., Metzler, C. F. 1993; 96 (2): 261–70

    Abstract

    The prediction of adult emergence times in insect populations can be greatly complicated by microclimatic gradients, especially in circumstances where distributions of juveniles along those gradients vary from year to year. To investigate adult emergence patterns in topographically heterogeneous habitats, we built a model of postdiapause development of the Bay checkerspot butterfly, Euphydryas editha bayensis. The model uses slope-specific insolation as the rate-controlling variable, and accounts for both solar exposure of the habitat and cloud cover. Instar-specific larval mass gains per unit of insolation were determined from mark-recapture experiments. A small correction for daily low temperatures was used to calibrate the model to five years of field data on larval mass. The model predicted mean mass of 90% of larval samples within 4 clear days over a 70-120 day growing season. The magnitude of spatial variation in emergence times across habitat slopes is greater than annual variation in emergence times due to yearly weather conditions. Historical variation (yearly shifts in larval distributions across slopes) is an important determinant of mean population emergence dates. All of these factors need to be considered in understanding adult emergence phenology in this butterfly and in other insects inhabiting heterogeneous thermal environments. Such an understanding can be useful in managing insect populations for both pest control and conservation.

    View details for PubMedID 28313423

  • ONE ECOLOGISTS OPINION ON THE SO-CALLED STANFORD SCANDALS AND SOCIAL-RESPONSIBILITY BIOSCIENCE Ehrlich, P. R. 1992; 42 (9): 702-705
  • THE VALUE OF BIODIVERSITY AMBIO Ehrlich, P. R., EHRLICH, A. H. 1992; 21 (3): 219-226
  • POPULATION-GROWTH AND ENVIRONMENTAL SECURITY GEORGIA REVIEW Ehrlich, P. R., EHRLICH, A. H. 1991; 45 (2): 223-232
  • WEVE RUN THE TEST POPULATION AND ENVIRONMENT Ehrlich, P. R. 1991; 12 (3): 189-191
  • Determinants of spatial distribution in a population of the subalpine butterfly Oeneis chryxus. Oecologia Daily, G. C., Ehrlich, P. R., Wheye, D. n. 1991; 88 (4): 587–96

    Abstract

    This paper describes temporally varying determinants of the spatial distribution of adults in an insect population and the relationship between that distribution and the mating system. Male Oeneis chryxus butterflies were distributed nonrandomly throughout a sloping Colorado meadow divided horizontally by a dirt road into an upper and lower slope. Over an eight-year period of intensive study, the proportion of males located on the road, the upper slope, and the lower slope varied as a function of population size and sex ratio. In each year, more than half of the male population aggregated on sections of the road in a distinct and recurring pattern that was not correlated with the distribution of any food resource or thermal regime. Females were usually extremely scarce and not distributed in any pattern apparent from the few observations of them. Areas densely occupied by males were associated with visual landmarks. We hypothesize that the male distribution is determined by a pattern of movement of receptive females toward these landmarks. The road offers a thermally favorable environment with an unobstructed view in which to await the passage of scarce females. The mating system in this population has several lek-like features and supports the prediction that landmark mating is a favored strategy under conditions of female scarcity and wide dispersal of resources.

    View details for PubMedID 28312631

  • AN EXPLORATORY MODEL OF THE IMPACT OF RAPID CLIMATE CHANGE ON THE WORLD FOOD SITUATION PROCEEDINGS OF THE ROYAL SOCIETY B-BIOLOGICAL SCIENCES Daily, G. C., Ehrlich, P. R. 1990; 241 (1302): 232-244

    Abstract

    A simple, globally aggregated, stochastic-simulation model was constructed to examine the effects of rapid climatic change on agriculture and the human population. The model calculates population size and the production, consumption and storage of grain under different climate scenarios over a 20-year projection time. In most scenarios, either an optimistic baseline annual increase of agricultural output of 1.7% or a more pessimistic appraisal of 0.9% was used. The rate of natural increase of the human population exclusive of excess hunger-related deaths was set as 1.7% per year and climatic changes with both negative and positive impacts on agriculture were assessed. Analysis of the model suggests that the number of hunger-related deaths could double (with reference to an estimated 200 million deaths in the past two decades) if grain production keeps pace with population growth but climatic conditions are unfavourable. If the rate of increase in grain production is about half that of population growth, the number of hunger-related deaths could increase about fivefold (over past levels); the impact of climatic change is relatively small under this imbalance. Even favourable climatic changes that enhance agricultural production may not prevent a fourfold increase in deaths (over past levels) under scenarios where population growth outpaces production by about 0.8% per annum. These results may foreshadow a fundamental change where, for the first time, absolute global food deficits compound inequities in food production and distribution in causing famine. The model also highlights the effectiveness of reducing population growth rates as a strategy for minimizing the impact of global climate change and maintaining food supplies for everyone.

    View details for Web of Science ID A1990ED14900012

    View details for PubMedID 1979448

  • HABITATS IN CRISIS - WHY WE SHOULD CARE ABOUT THE LOSS OF SPECIES FOREST ECOLOGY AND MANAGEMENT Ehrlich, P. R. 1990; 35 (1-2): 5-11
  • A REEXAMINATION OF HILLTOPPING IN EUPHYDRYAS-EDITHA OECOLOGIA BAUGHMAN, J. F., Murphy, D. D., Ehrlich, P. R. 1990; 83 (2): 259-260

    View details for Web of Science ID A1990DG37300017

    View details for PubMedID 22160120

  • INTELLIGENT PLANNING FOR SAFETY SOCIETY Ehrlich, P. R., EHRLICH, A. H. 1989; 27 (1): 15-16
  • THE ENVIRONMENTAL DIMENSIONS OF NATIONAL-SECURITY PUGWASH CONF ON GLOBAL PROBLEMS AND COMMON SECURITY Ehrlich, P., Ehrlich, A. SPRINGER-VERLAG BERLIN. 1989: 180–190
  • PLANT CHEMISTRY AND HOST RANGE IN INSECT HERBIVORES ECOLOGY Ehrlich, P. R., Murphy, D. D. 1988; 69 (4): 908-909
  • POPULATION-STRUCTURE OF A HILLTOPPING BUTTERFLY OECOLOGIA BAUGHMAN, J. F., Murphy, D. D., Ehrlich, P. R. 1988; 75 (4): 593-600
  • WHY THE CLUB OF EARTH TRENDS IN ECOLOGY & EVOLUTION Ehrlich, P. R. 1987; 2 (5): 133-135

    Abstract

    Recently, a small group of ecologists and evolutionary biologists anointed themselves The Club of Earth and made a public pronouncement on the importance of preserving biological diversity. For me, the most frequent result of being a member has been a series of queries about why the group had been formed.

    View details for Web of Science ID A1987H511700007

    View details for PubMedID 21227835

  • HUMAN APPROPRIATION OF THE PRODUCTS OF PHOTOSYNTHESIS BIOSCIENCE Vitousek, P. M., Ehrlich, P. R., EHRLICH, A. H., Matson, P. A. 1986; 36 (6): 368-373
  • WORLD-POPULATION CRISIS BULLETIN OF THE ATOMIC SCIENTISTS Ehrlich, P. R., EHRLICH, A. H. 1986; 42 (4): 13-19
  • DURATION OF FEMALE AVAILABILITY AND ITS EFFECT ON BUTTERFLY MATING SYSTEMS AMERICAN NATURALIST Odendaal, F. J., Iwasa, Y., Ehrlich, P. R. 1985; 125 (5): 673-678
  • A MIGRATION OF URANIA-FULGENS (URANIIDAE) IN COSTA-RICA BIOTROPICA Odendaal, F. J., Ehrlich, P. R. 1985; 17 (1): 46-49
  • HUMAN-ECOLOGY FOR INTRODUCTORY BIOLOGY COURSES - AN OVERVIEW AMERICAN ZOOLOGIST Ehrlich, P. R. 1985; 25 (2): 379-394
  • THE USE OF FLUORESCENT PIGMENTS TO STUDY INSECT BEHAVIOR - INVESTIGATING MATING PATTERNS IN A BUTTERFLY POPULATION ECOLOGICAL ENTOMOLOGY WHEYE, D., Ehrlich, P. R. 1985; 10 (2): 231-234
  • CITATION CLASSIC - BUTTERFLIES AND PLANTS - A STUDY IN COEVOLUTION CURRENT CONTENTS/LIFE SCIENCES Ehrlich, P. R. 1984: 16-16
  • Nectar source distribution as a determinant of oviposition host species in Euphydryas chalcedona. Oecologia Murphy, D. D., Menninger, M. S., Ehrlich, P. R. 1984; 62 (2): 269–71

    Abstract

    The distribution of nectar sources is shown to affect both the distribution of adult Euphydryas chalcedona and their offspring. We suggest that nectar sources thereby influence the selection of oviposition host plant species in habitats where those species are spacially separated.

    View details for PubMedID 28310725

  • CITATION CLASSIC - BUTTERFLIES AND PLANTS - A STUDY IN COEVOLUTION CURRENT CONTENTS/AGRICULTURE BIOLOGY & ENVIRONMENTAL SCIENCES Ehrlich, P. R. 1984: 16-16
  • NECTAR SOURCE DISTRIBUTION AS A DETERMINANT OF OVIPOSITION HOST SPECIES IN EUPHYDRYAS-CHALCEDONA OECOLOGIA Murphy, D. D., MENNINGER, M. S., Ehrlich, P. R. 1984; 62 (2): 269-271

    Abstract

    The distribution of nectar sources is shown to affect both the distribution of adult Euphydryas chalcedona and their offspring. We suggest that nectar sources thereby influence the selection of oviposition host plant species in habitats where those species are spacially separated.

    View details for Web of Science ID A1984SV09400020

  • NORTH-AMERICA AFTER THE WAR NATURAL HISTORY Ehrlich, P. R. 1984; 93 (3): 4-?
  • EXTINCTION, SUBSTITUTION, AND ECOSYSTEM SERVICES BIOSCIENCE Ehrlich, P. R., Mooney, H. A. 1983; 33 (4): 248-254
  • The role of adult feeding in egg production and population dynamics of the checkerspot butterfly Euphydryas editha. Oecologia Murphy, D. D., Launer, A. E., Ehrlich, P. R. 1983; 56 (2-3): 257–63

    Abstract

    Carbohydrate intake increases longevity, body weight maintenance and egg production in female Euphydryas editha. Amino acid intake leads to heavier eggs, larvae from which are more likely to survive. Females fed nectar produce more eggs in later masses than females which are not fed. During years of normal and below normal precipitation, larvae emerging from these later eggs are unlikely to reach obligatory size for diapause before their food dries up. On Jasper Ridge, where mortality is density-independent, nectar plays an important role increasing production of late egg masses during years of greater than normal rainfall when larvae from these masses are likely to reach diapause. The resulting large population increases, though infrequent, are probably important in maintaining population sizes large enough to reduce the chances of extinction during dry years.

    View details for PubMedID 28310203

  • ECOLOGICAL DETERMINANTS OF FOOD PLANT CHOICE IN THE CHECKERSPOT BUTTERFLY EUPHYDRYAS-EDITHA IN COLORADO OECOLOGIA Holdren, C. E., Ehrlich, P. R. 1982; 52 (3): 417-423

    Abstract

    The larvae of Euphydryas editha in Gunnison County, Colorado, feed on Castilleja linariifolia. Two related plants, C. chromosa and Penstemon strictus, occur in the same area and are equally nutritious, but are not eaten. Restriction to C. linariifolia appears to be a case of ecological monophagy - survival on the other two species is less likely not because of their biochemical make-up but because of their ecological characteristics, primarily their phenologies.

    View details for Web of Science ID A1982NH64800020

  • Ecological determinants of food plant choice in the checkerspot butterfly Euphydryas editha in Colorado. Oecologia Holdren, C. E., Ehrlich, P. R. 1982; 52 (3): 417–23

    Abstract

    The larvae of Euphydryas editha in Gunnison County, Colorado, feed on Castilleja linariifolia. Two related plants, C. chromosa and Penstemon strictus, occur in the same area and are equally nutritious, but are not eaten. Restriction to C. linariifolia appears to be a case of ecological monophagy - survival on the other two species is less likely not because of their biochemical make-up but because of their ecological characteristics, primarily their phenologies.

    View details for PubMedID 28310406

  • HUMAN CARRYING-CAPACITY, EXTINCTIONS, AND NATURE RESERVES BIOSCIENCE Ehrlich, P. R. 1982; 32 (5): 331-333
  • EXTINCTION OR A STRATEGY OF CONSERVATION BULLETIN OF THE ATOMIC SCIENTISTS Ehrlich, P., Ehrlich, A. 1981; 37 (6): 25-30
  • Long range dispersal in checkerspot butterflies: Transplant experiments with Euphydryas gillettii. Oecologia Holdren, C. E., Ehrlich, P. R. 1981; 50 (1): 125–29

    Abstract

    Transfers of eggs and larvae from montane Wyoming populations of Euphydryas gillettii south to locations in the central Colorado mountains have resulted in the establishment of at least one Colorado population. This result shows that the previous absence of the species from Colorado was the result of its inability to cross the barrier of the Wyoming Basin, not the ecological unsuitability of Colorado habitats. This, in turn, supports the contention that Euphydryas do not easily disperse long distances.

    View details for PubMedID 28310073

  • THE POPULATION BIOLOGY OF CHECKERSPOT BUTTERFLIES (EUPHYDRYAS) BIOLOGISCHES ZENTRALBLATT Ehrlich, P. R., Murphy, D. D. 1981; 100 (6): 613-629
  • THE COMMUNITY STRUCTURE OF CORAL-REEF FISHES AMERICAN NATURALIST ANDERSON, G. R., EHRLICH, A. H., Ehrlich, P. R., ROUGHGARDEN, J. D., Russell, B. C., TALBOT, F. H. 1981; 117 (4): 476-495
  • THE POLITICS OF EXTINCTION BULLETIN OF THE ATOMIC SCIENTISTS Ehrlich, P., Ehrlich, A. 1981; 37 (5): 26-30
  • LONG-RANGE DISPERSAL IN CHECKERSPOT BUTTERFLIES - TRANSPLANT EXPERIMENTS WITH EUPHYDRYAS-GILLETTII OECOLOGIA Holdren, C. E., Ehrlich, P. R. 1981; 50 (1): 125-129

    Abstract

    Transfers of eggs and larvae from montane Wyoming populations of Euphydryas gillettii south to locations in the central Colorado mountains have resulted in the establishment of at least one Colorado population. This result shows that the previous absence of the species from Colorado was the result of its inability to cross the barrier of the Wyoming Basin, not the ecological unsuitability of Colorado habitats. This, in turn, supports the contention that Euphydryas do not easily disperse long distances.

    View details for Web of Science ID A1981MD22000018

  • AN ECONOMIST IN WONDERLAND SOCIAL SCIENCE QUARTERLY Ehrlich, P. R. 1981; 62 (1): 44-49
  • POPULATION BIOLOGY OF THE CHECKERSPOT BUTTERFLY, EUPHYDRYAS-CHALCEDONA STRUCTURE OF THE JASPER RIDGE COLONY OECOLOGIA Brown, I. L., Ehrlich, P. R. 1980; 47 (2): 239-251

    Abstract

    Euphydryas chalcedona at Jasper Ridge consists of two independently varying major demographic units, similar in scale but not in structure to those of Euphydryas editha. In contrast, however, Jasper Ridge E. chalcedona represent just a portion of a deme-while E. editha occurs as two partially connected demes. The life history and general ecology of E. chalcedona is described and compared with those of its intensively-studied congener. Various problems of mark-release-recapture estimation of population size are discussed.

    View details for Web of Science ID A1980KU37400016

  • Population biology of the checkerspot butterfly, Euphydryas chalcedona structure of the Jasper Ridge colony. Oecologia Brown, I. L., Ehrlich, P. R. 1980; 47 (2): 239–51

    Abstract

    Euphydryas chalcedona at Jasper Ridge consists of two independently varying major demographic units, similar in scale but not in structure to those of Euphydryas editha. In contrast, however, Jasper Ridge E. chalcedona represent just a portion of a deme-while E. editha occurs as two partially connected demes. The life history and general ecology of E. chalcedona is described and compared with those of its intensively-studied congener. Various problems of mark-release-recapture estimation of population size are discussed.

    View details for PubMedID 28309478

  • VARIETY IS THE KEY TO LIFE TECHNOLOGY REVIEW Ehrlich, P. R. 1980; 82 (5): 58-?
  • POPULATION-DYNAMICS OF THE CHECKERSPOT BUTTERFLY EUPHYDRYAS-EDITHA FORTSCHRITTE DER ZOOLOGIE Singer, M. C., Ehrlich, P. R. 1979; 25 (2-3): 53-60
  • WHAT HAPPENED TO THE POPULATION BOMB HUMAN NATURE Ehrlich, P. R., EHRLICH, A. H. 1979; 2 (1): 88-92
  • B-CHROMOSOME VARIATION IN EUPHYDRYAS-COLON (LEPIDOPTERA, NYMPHALIDAE) CHROMOSOMA PEARSE, F. K., Ehrlich, P. R. 1979; 73 (3): 263-274
  • STEADY-STATE ECONOMICS - DALY,HE HUMAN NATURE Ehrlich, P. R. 1978; 1 (8): 20-?
  • POPULATION BIOLOGY OF CORAL-REEF FISHES ANNUAL REVIEW OF ECOLOGY AND SYSTEMATICS Ehrlich, P. R. 1975; 6: 211-246
  • BENEFITS OF SAYING YES BULLETIN OF THE ATOMIC SCIENTISTS Ehrlich, P. R. 1975; 31 (7): 49-51
  • PLANT RESOURCES AND BUTTERFLY HABITAT SELECTION ECOLOGY Sharp, M. A., Parks, D. R., Ehrlich, P. R. 1974; 55 (4): 870-875
  • ADULT MOVEMENTS AND POPULATION STRUCTURE IN EUPHYDRYAS-EDITHA EVOLUTION Brussard, P. F., Ehrlich, P. R., Singer, M. C. 1974; 28 (3): 408-415
  • THIRD-WORLD ATTITUDES ATMOSPHERIC ENVIRONMENT Ehrlich, P. R. 1974; 8 (5): 523-524
  • COEVOLUTION - HETEROTYPIC SCHOOLING IN CARIBBEAN REEF FISHES AMERICAN NATURALIST Ehrlich, P. R., EHRLICH, A. H. 1973; 107 (953): 157-160
  • CRYING NEED FOR QUIET CONFERENCES - PERSONAL NOTES FROM STOCKHOLM SCIENCE AND PUBLIC AFFAIRS-BULLETIN OF THE ATOMIC SCIENTISTS Ehrlich, P. R. 1972; 28 (7): 30-32
  • EFFECT OF CROWDING ON HUMAN TASK PERFORMANCE JOURNAL OF APPLIED SOCIAL PSYCHOLOGY Freedman, J. L., Klevansky, S., Ehrlich, P. R. 1971; 1 (1): 7-25