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Research & Scholarship

Current Research and Scholarly Interests


The role of the social sciences in dealing with global change

Teaching

Graduate and Fellowship Programs


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

Publications

Journal Articles


  • 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

  • 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

  • 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

  • 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 Web of Science ID 000278125500001

    View details for PubMedID 20386722

  • 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

  • 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

  • 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

  • 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

  • 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

  • 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

  • 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

  • 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

  • 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

  • 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 Web of Science ID 000075666800027

    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

  • 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

  • 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

  • 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

  • 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

  • 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

  • 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

Conference Proceedings


  • Intervening in evolution: Ethics and actions Ehrlich, P. R. NATL ACAD SCIENCES. 2001: 5477-5480

    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

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