Showing papers in "Conservation Biology in 2003"

Correlation between Fitness and Genetic Diversity

Abstract: Genetic diversity is one of the three forms of biodiversity recognized by the World Conservation Union (IUCN) as deserving conservation. The need to conserve genetic diversity within populations is based on two arguments: the necessity of genetic diversity for evolution to occur, and the expected relation- ship between heterozygosity and population fitness. Because loss of genetic diversity is related to inbreed- ing, and inbreeding reduces reproductive fitness, a correlation is expected between heterozygosity and pop- ulation fitness. Long-term effective population size, which determines rates of inbreeding, should also be correlated with fitness. However, other theoretical considerations and empirical observations suggest that the correlation between fitness and heterozygosity may be weak or nonexistent. We used all the data sets we could locate (34) to perform a meta-analysis and resolve the issue. Data sets were included in the study, provided that fitness, or a component of fitness, was measured for three or more populations along with heterozygosity, heritability, and/or population size. The mean weighted correlation between measures of genetic diversity, at the population level, and population fitness was 0.4323. The correlation was highly sig- nificant and explained 19% of the variation in fitness. Our study strengthens concerns that the loss of het- erozygosity has a deleterious effect on population fitness and supports the IUCN designation of genetic di- versity as worthy of conservation.

Human-Carnivore Conflict and Perspectives on Carnivore Management Worldwide

Abstract: Carnivore conservation depends on the sociopolitical landscape as much as the biological landscape. Changing political attitudes and views of nature have shifted the goals of carnivore management from those based on fear and narrow economic interests to those based on a better understanding of ecosystem function and adaptive management. In parallel, aesthetic and scientific arguments against lethal control techniques are encouraging the development of nonlethal approaches to carnivore management. We anticipate greater success in modifying the manner and frequency with which the activities of humans and domestic animals intersect with those of carnivores. Success should permit carnivore populations to persist for decades despite human population growth and modification of habitat.

Scenario Planning: a Tool for Conservation in an Uncertain World

Abstract: Conservation decisions about how, when, and where to act are typically based on our expectations for the future. When the world is highly unpredictable and we are working from a limited range of expecta- tions, however, our expectations will frequently be proved wrong. Scenario planning offers a framework for developing more resilient conservation policies when faced with uncontrollable, irreducible uncertainty. A scenario in this context is an account of a plausible future. Scenario planning consists of using a few con- trasting scenarios to explore the uncertainty surrounding the future consequences of a decision. Ideally, sce- narios should be constructed by a diverse group of people for a single, stated purpose. Scenario planning can incorporate a variety of quantitative and qualitative information in the decision-making process. Often, con- sideration of this diverse information in a systemic way leads to better decisions. Furthermore, the participa- tion of a diverse group of people in a systemic process of collecting, discussing, and analyzing scenarios builds shared understanding. The robustness provided by the consideration of multiple possible futures has served several groups well; we present examples from business, government, and conservation planning that illustrate the value of scenario planning. For conservation, major benefits of using scenario planning are (1) increased understanding of key uncertainties, (2) incorporation of alternative perspectives into conservation planning, and (3) greater resilience of decisions to surprise.

Biological Criteria for Buffer Zones around Wetlands and Riparian Habitats for Amphibians and Reptiles

Abstract: Terrestrial habitats surrounding wetlands are critical to the management of natural resources. Al- though the protection of water resources from human activities such as agriculture, silviculture, and urban development is obvious, it is also apparent that terrestrial areas surrounding wetlands are core habitats for many semiaquatic species that depend on mesic ecotones to complete their life cycle. For purposes of conser- vation and management, it is important to define core habitats used by local breeding populations surround- ing wetlands. Our objective was to provide an estimate of the biologically relevant size of core habitats sur- rounding wetlands for amphibians and reptiles. We summarize data from the literature on the use of terrestrial habitats by amphibians and reptiles associated with wetlands (19 frog and 13 salamander species representing 1363 individuals; 5 snake and 28 turtle species representing more than 2245 individuals). Core terrestrial habitat ranged from 159 to 290 m for amphibians and from 127 to 289 m for reptiles from the edge of the aquatic site. Data from these studies also indicated the importance of terrestrial habitats for feed- ing, overwintering, and nesting, and, thus, the biological interdependence between aquatic and terrestrial habitats that is essential for the persistence of populations. The minimum and maximum values for core hab- itats, depending on the level of protection needed, can be used to set biologically meaningful buffers for wet- land and riparian habitats. These results indicate that large areas of terrestrial habitat surrounding wetlands are critical for maintaining biodiversity.

Introduction: Population Biology, Evolution, and Control of Invasive Species

Abstract: Invasion by nonindigenous species has been recognized as second only to loss of habitat and landscape fragmentation as a threat to global biodiversity (Walker & Steffen 1997). The economic impact of these species is a major concern throughout the world. For example, an estimated 50,000 nonindigenous species established in the United States cause major environmental damage and economic losses that total over an estimated U.S.$125 billion per year (Pimentel et al. 2000). Management and control of nonindigenous species is perhaps the biggest challenge that conservation biologists will face in the next few decades. The six papers in this special section and these introductory remarks consider the role that population biology can play in understanding invasive species through life-history studies, demographic models, genetic considerations, and knowledge of the ecology and evolution of both invasive and native species in a community context. Studies of genetic diversity and the potential for rapid evolution of invasive species may provide useful insights into what causes species to become invasive. Life-history studies may also lead to predictions of which species are likely to become serious pests or identify critical life-history stages during which control will be most successful. Population biology might be useful in identifying the point where containment rather than eradication efforts would be more practical. Demographic models may be useful for examining the spread of invasive species and methods of control. More information about the genetics and evolution of invasive species or native species in invaded communities, as well as their interactions, may lead to predictions of the relative susceptibility of ecosystems to invasion, identification of key alien species, and predictions of the subsequent effects of removal. Two major themes emerge from the papers in this special section. First, invasive species provide an exceptional opportunity for basic research in the population biology and short-term evolution of species. Many unresolved central issues in the application of genetics to conservation—such as the inbreeding effects of small populations and the importance of local adaptation—can be much better experimentally addressed with introduced species. Second, the management and control of invasive species is a controversial and incredibly complex problem. There may be much to be gained from the study of introduced species, but it is unclear how much this increased understanding of the biology of invasive species will be helpful in their management and control. In addition, the use of biological controls introduces a completely new set of dangers.

Forecasting Biological Invasions with Increasing International Trade

Abstract: We used historical data to parameterize species-accumulation models relating international trade to the establishment rates of nonindigenous species in the United States over the past century. We then cou- pled these relationships with published trade forecasts to predict future invasion rates for insects, plant patho- gens, and mollusks. Relationships between the accumulation of non-native species and merchandise imports were reasonably described by log-log and log-linear species-area models and Michaelis-Menten accumulation functions. However, the latter two models produced markedly better fits. When coupled with projected trade forecasts, the log-linear species-area model predicted 16-24% taxon-specific increases in the number of nonin- digenous species established in the United States from 2000 to 2020. The Michaelis-Menten model predicted much lower 3-6% increases, but even this meant 115 new insect species and 5 new plant pathogens. These re- sults suggest that the ecological and economic costs associated with human-caused biological invasions may continue to rise substantially over the coming decades. Prediccion de las Invasiones Biologicas con el Incremento del Comercio Internacional Resumen: Empleamos datos historicos para parametrizar modelos de acumulacion de especies relacion- ando el comercio internacional con las tasas de establecimiento de especies no-indigenas en los Estados Uni- dos a lo largo del siglo pasado. Posteriormente acoplamos estas relaciones con predicciones de mercado pub- licadas para determinar las tasas futuras de invasion para insectos, patogenos de plantas y moluscos. Las relaciones entre la acumulacion de especies no nativas y las mercancias de importacion fue razonablemente descrita por modelos de especies-areas log-log y log-lineal y las funciones de acumulacion de Michaelis- Menten. Sin embargo, estos ultimos dos modelos produjeron ajustes notablemente mejores. Cuando se acop- laron con predicciones de mercado proyectadas, los modelos de especie-area logaritmicas-lineales predijeron incrementos especificos de taxon del 16-24% en el numero de especies no indigenas establecidas en los Esta- dos Unidos del 2000 al 2020. El modelo de Michaelis-Menten predijo incrementos mucho menores del 3-6%, pero aun esto representa 115 nuevas especies de insectos y 5 nuevas especies de patogenos de plantas. Estos resultados sugieren que los costos ecologicos y economicos asociados con las invasiones biologicas causadas por humanos podrian continuar incrementandose sustancialmente a lo largo de las siguientes decadas.

Roads as Conduits for Exotic Plant Invasions in a Semiarid Landscape

Abstract: Roads are believed to be a major contributing factor to the ongoing spread of exotic plants. We ex- amined the effect of road improvement and environmental variables on exotic and native plant diversity in roadside verges and adjacent semiarid grassland, shrubland, and woodland communities of southern Utah (U.S.A.). We measured the cover of exotic and native species in roadside verges and both the richness and cover of exotic and native species in adjacent interior communities (50 m beyond the edge of the road cut) along 42 roads stratified by level of road improvement ( paved, improved surface, graded, and four-wheel- drive track ). In roadside verges along paved roads, the cover of Bromus tectorum was three times as great (27%) as in verges along four-wheel-drive tracks ( 9%). The cover of five common exotic forb species tended to be lower in verges along four-wheel-drive tracks than in verges along more improved roads. The richness and cover of exotic species were both more than 50% greater, and the richness of native species was 30% lower, at interior sites adjacent to paved roads than at those adjacent to four-wheel-drive tracks. In addition, environmental variables relating to dominant vegetation, disturbance, and topography were significantly correlated with exotic and native species richness and cover. Improved roads can act as conduits for the inva- sion of adjacent ecosystems by converting natural habitats to those highly vulnerable to invasion. However, variation in dominant vegetation, soil moisture, nutrient levels, soil depth, disturbance, and topography may render interior communities differentially susceptible to invasions originating from roadside verges. Plant communities that are both physically invasible (e.g., characterized by deep or fertile soils) and disturbed ap- pear most vulnerable. Decision-makers considering whether to build, improve, and maintain roads should take into account the potential spread of exotic plants.

Resistance and Resilience to Coral Bleaching: Implications for Coral Reef Conservation and Management

Abstract: The massive scale of the 1997–1998 El Nino–associated coral bleaching event underscores the need for strategies to mitigate biodiversity losses resulting from temperature-induced coral mortality. As baseline sea surface temperatures continue to rise, climate change may represent the single greatest threat to coral reefs worldwide. In response, one strategy might be to identify ( 1 ) specific reef areas where natural environmental conditions are likely to result in low or negligible temperature-related bleaching and mortality ( i.e., areas of natural “resistance” to bleaching ) and ( 2 ) reef areas where environmental conditions are likely to result in maximum recovery of reef communities after bleaching mortality has occurred ( i.e., areas of natural community “resilience” ). These “target areas,” where environmental conditions appear to boost resistance and resilience during and after large-scale bleaching events, could then be incorporated into strategic networks of marine protected areas designed to maximize conservation of global coral reef biodiversity. Based on evidence from the literature and systematically compiled observations from researchers in the field, this paper identifies likely environmental correlates of resistance and resilience to coral bleaching, including factors that reduce temperature stress, enhance water movement, decrease light stress, correlate with physiological tolerance, and provide physical or biological enhancement of recovery potential. As a tool for identifying reef areas that are likely to be most robust in the face of continuing climate change and for determining priority areas for reducing direct anthropogenic impacts, this information has important implications for coral reef conservation and management.

Limiting Depredation by African Carnivores: the Role of Livestock Husbandry

Abstract: Most large carnivore species are in global decline. Conflict with local people, particularly over depredation on livestock, is a major cause of this decline, affecting both nominally protected populations and those outside protected areas. For this reason, techniques that can resolve conflicts between large carnivores and livestock farmers may make important contributions to conservation. We monitored rates of livestock depredation by lions (Panthera leo), leopards (Panthera pardus), cheetahs (Acinonyx jubatus), and spotted hyenas (Crocuta crocuta), and retributive killing of these species by farmers in livestock-producing areas of Laikipia District, Kenya. Farmers killed more lions, leopards, and spotted hyenas where these predators killed more livestock. Livestock husbandry had a clear effect on rates of depredation and hence on the numbers of predators killed. Cattle, sheep, and goats experienced the lowest predation rates when attentively herded by day and enclosed in traditional corrals (bomas) by night. Construction of the boma, the presence of watchdogs, and high levels of human activity around the boma were all associated with lower losses to predators. Although most of this work was carried out on commercial ranches, local Maasai and Samburu pastoralists have practiced nearly identical forms of husbandry for generations. Our study shows that traditional, low-tech husbandry approaches can make an important contribution to the conservation of large carnivores.

Effect of Forest Fragmentation on Lyme Disease Risk

Abstract: Forest destruction and fragmentation in the United States recently have been shown to reduce mammalian species diversity and to elevate population densities of white-footed mice ( Peromyscus leucopus ). One potential consequence of reduced species diversity and high mouse density in small fragments is an increase in human exposure to Lyme disease. Increased risk of exposure to this disease is expected be- cause of the role of the white-footed mouse as the principal natural reservoir of the Lyme bacterium, Borrelia burgdorferi . Blacklegged ticks ( Ixodes scapularis ) feeding on mice have a higher probability of becoming in- fected with the bacterium than do ticks feeding on any other host species. We hypothesized that small forest patches ( � 2 ha) have a higher density of infected nymphal blacklegged ticks, which is the primary risk factor for Lyme disease, than larger patches ( 2-8 ha). In the summer of 2000, we sampled tick density and B. burg- dorferi infection prevalence in 14 maple-dominated forest patches, ranging in size from 0.7 to 7.6 ha, in Dutchess County of southeastern New York state. We found a significant linear decline in nymphal infection prevalence with increasing patch area and a significant exponential decline in nymphal density with increas- ing patch area. The consequence was a dramatic increase in the density of infected nymphs, and therefore in Lyme disease risk, with decreasing forest patch size. We did not observe a similar relationship between the density of larval ticks and patch size. These results suggest that by influencing the community composition of vertebrate hosts for disease-bearing vectors, habitat fragmentation can influence human health.

How Much Information on Population Biology Is Needed to Manage Introduced Species

Abstract: Study of the population biology of introduced species has elucidated many fundamental questions in ecology and evolution. Detailed population biological research is likely to aid in fine-tuning control of widespread and/or long-established invasions, and it may lead to novel control methods. It will also contrib- ute to an overall understanding of the invasion process that may aid in the formulation of policy and help to focus attention on invasions that are especially prone to becoming problematic. But the importance of inten- sive population biological research in dealing with introduced species, especially those recently introduced, is often limited. In the worst instances, the absence of population biological data can be an excuse for inaction, when a prudent decision or quick and dirty operation might have excluded or eliminated an invader. The most effective way to deal with invasive introduced species, short of keeping them out, is to discover them early and attempt to eradicate or at least contain them before they spread. This approach has often been suc- cessful, but its success has usually relied on brute-force chemical and mechanical techniques, not on popula- tion biological research.

Avoiding Pitfalls of Using Species-Distribution Models in Conservation Planning

Abstract: : Museum records have great potential to provide valuable insights into the vulnerability, historic distribution, and conservation of species, especially when coupled with species-distribution models used to predict species' ranges. Yet, the increasing dependence on species-distribution models in identifying conservation priorities calls for a more critical evaluation of model robustness. We used 11 bird species of conservation concern in Brazil's highly fragmented Atlantic Forest and data on environmental conditions in the region to predict species distributions. These predictions were repeated for five different model types for each of the 11 bird species. We then combined these species distributions for each model separately and applied a reserve-selection algorithm to identify priority sites. We compared the potential outcomes from the reserve selection among the models. Although similarity in identification of conservation reserve networks occurred among models, models differed markedly in geographic scope and flexibility of reserve networks. It is essential for planners to evaluate the conservation implications of false-positive and false-negative errors for their specific management scenario before beginning the modeling process. Reserve networks selected by models that minimized false-positive errors provided a better match with priority areas identified by specialists. Thus, we urge caution in the use of models that overestimate species' occurrences because they may misdirect conservation action. Our approach further demonstrates the great potential value of museum records to biodiversity studies and the utility of species-distribution models to conservation decision-making. Our results also demonstrate, however, that these models must be applied critically and cautiously. Resumen: Los registros de museos tienen un gran valor potencial al proporcionar entendimiento sobre la vulnerabilidad, distribucion historica y conservacion de especies, especialmente cuando se combinan con modelos de distribucion de especies utilizados para predecir los rangos de distribucion de las especies. No obstante, la mayor dependencia sobre los modelos de distribucion de especies para la identificacion de prioridades de conservacion requiere una evaluacion critica de la robustez del modelo. Utilizamos 11 especies de aves de interes para la conservacion en el muy fragmentado Bosque Atlantico en Brasil asi como datos de condiciones ambientales en la region para predecir la distribucion de las especies. Estas predicciones fueron repetidas para cinco tipos diferentes de modelos para cada una de las 11 especies de aves. Luego combinamos estas distribuciones de especies para cada modelo por separado y aplicamos un algoritmo de seleccion de reservas para identificar sitios prioritarios. Comparamos los resultados potenciales de la seleccion de reservas entre modelos. Aunque hubo similitud entre los modelos en la identificacion de redes de reservas, los modelos difirieron marcadamente en el alcance geografico y la flexibilidad de las redes de reservas. Es de importancia fundamental para los planificadores evaluar las implicaciones sobre la conservacion de errores falsos positivos y falsos negativos para su escenario de manejo especifico antes de comenzar el proceso de modelado. Las redes de reservas seleccionadas por modelos que minimizaron los errores falsos positivos proporcionaron mejor correspondencia con las areas prioritarias identificadas por especialistas. Por lo tanto, instamos a tener precaucion con el uso de modelos que sobreestiman la ocurrencia de especies porque pueden desviar las acciones de conservacion. Nuestro metodo demuestra ademas el gran potencial de los registros de museos en estudios de biodiversidad y la utilidad de los modelos de distribucion de especies para la toma de decisiones de conservacion. Sin embargo, nuestros resultados demuestran que estos modelos deben ser aplicados critica y cuidadosamente.

Paying for Tolerance: Rural Citizens' Attitudes toward Wolf Depredation and Compensation

Abstract: As wolf ( Canis lupus) populations recover in Wisconsin (U.S.A.), their depredations on livestock, pets, and hunting dogs have increased. We used a mail-back survey to assess the tolerance of 535 rural cit- izens of wolves and their preferences regarding the management of "problem" wolves. Specifically, we tested whether people who had lost domestic animals to wolves or other predators were less tolerant of wolves than neighboring residents who had not and whether compensation payments improved tolerance of wolves. We assessed tolerance via proxy measures related to an individual's preferred wolf population size for Wisconsin and the likelihood she or he would shoot a wolf. We also measured individuals' approval of lethal control and other wolf-management tactics under five conflict scenarios. Multivariate analysis revealed that the strongest predictor of tolerance was social group. Bear ( Ursus americanus) hunters were concerned about losing valu- able hounds to wolves and were more likely to approve of lethal control and reducing the wolf population than were livestock producers, who were more concerned than general residents. To a lesser degree, education level, experience of loss, and gender were also significant. Livestock producers and bear hunters who had been compensated for their losses to wolves were not more tolerant than their counterparts who alleged a loss but received no compensation. Yet all respondents approved of compensation payments as a management strategy. Our results indicate that deep-rooted social identity and occupation are more powerful predictors of tolerance of wolves than individual encounters with these large carnivores.

Effects of Urbanization and Habitat Fragmentation on Bobcats and Coyotes in Southern California

Abstract: Urbanization and habitat fragmentation are major threats to wildlife populations, especially mammalian carnivores. We studied the ecology and behavior of bobcats ( Lynx rufus ) and coyotes ( Canis latrans ) relative to development in a fragmented landscape in southern California from 1996 to 2000. We captured and radiocollared 50 bobcats and 86 coyotes, determined home ranges for 35 bobcats and 40 coyotes, and measured their exposure to development ( “urban association” ) as the percentage of each home range composed of developed or modified areas. Both species occupied predominantly natural home ranges. Adult female bobcats had low levels of urban association, significantly lower than coyotes, adult male bobcats, and young female bobcats. Home-range size was positively correlated with urban association for coyotes and adult male and young female bobcats, suggesting that human-dominated areas were less suitable than natural areas in some important way. Animals more associated with non-natural areas had higher levels of night activity, and both bobcats and coyotes were more likely to be in developed areas at night than during the day. Survival rates were relatively high and were not related to urban association, at least for animals>6–9 months of age. Mortality rates from human-related causes such as vehicle collisions and incidental poisoning were also independent of urban association. In this region, even the few animals that had almost no human development within their home range were vulnerable to human-related mortality. Carnivore conservation in urban landscapes must account for these mortality sources that influence the entire landscape, including reserves. For bobcats, preserving open space of sufficient quantity and quality for adult females is necessary for population viability. Educating local residents about carnivores is also critical for conserving populations in urban areas.

Ecological Effectiveness: Conservation Goals for Interactive Species

Abstract: The rarity or absence of highly interactive species leaves a functional void that can trigger linked changes leading to degraded or simplified ecosystems. A preliminary analysis indicates a relatively high frequency of such interactive species among endangered mammals. Rapid environmental change is likely to increase the interactivity of some species and reduce that of others over relatively short intervals. The current implementation of environmental policies and laws, such as the U.S. Endangered Species Act, generally ignores interspecific effects; recovery goals are autecological, short term, and numerically and spatially minimalistic. Moreover, by failing to account for interspecific interactions, recovery objectives are becoming indefensible in light of increasing knowledge from community ecology. Using the sea otter ( Enhydra lutris ) and wolf ( Canis lupus ) as examples, we argue that conservation plans should call for recovery or repatriation of such interactive species at ecologically effective densities in as many places as are currently realistic. It will be prudent and beneficial to estimate ecologically effective densities where there is disagreement among experts and interested parties about the desirability of restoring an interactive species to a particular region and to a particular density.

Additive Partitioning of Species Diversity across Multiple Spatial Scales: Implications for Regional Conservation of Biodiversity

Abstract: Ecologists and conservation biologists are keenly interested in how patterns of species diversity change across spatial scales. We examined how additive partitioning can be used to statistically evaluate spa- tial patterns of species diversity and develop conservation strategies. We applied additive partitioning to data on arboreal beetle diversity (richness, Shannon, Simpson) collected from a nested design consisting of four hi- erarchical levels—trees, forest stands, sites, and ecoregions—that corresponded to increasingly broader spa- tial scales within the eastern deciduous forest of Ohio and Indiana ( U.S.A.). A significant percentage (relative to that of randomization tests) of total species richness and Shannon and Simpson diversity was attributed to beta diversity between ecoregions and, to a lesser extent, among sites (parks and nature preserves) within ecoregions. Hierarchical cluster analysis corroborated these findings. We also found differences between rare species ( � 0.05% of total abundance) and common species ( � 0.5% of total abundance) in the overall per- centage of richness explained by each spatial scale. Rare species accounted for the majority (45%) of the 583 total beetle species in our study and were strongly influenced by broad spatial scales (i.e., ecoregions), whereas the richness of common species was significantly greater than expected across the range of spatial scales ( from trees to ecoregions). Our results suggest that the most effective way to preserve beetle diversity in the eastern deciduous forest of the United States is to acquire and protect multiple sites within different ecoregions. More generally, we advocate the use of diversity partitioning because it complements existing models in conserva- tion biology and provides a unique approach to understanding species diversity across spatial scales.

Ecological traits predicting amphibian population declines in Central America

Abstract: Amphibian populations are declining on all continents on which they occur, but not all species have been affected equally. Populations of some species are extirpated, others have declined but survive, some have not obviously declined, and some are increasing. If amphibian populations at multiple sites were affected by the same factors, then surviving species should share traits that promote persistence, whereas declining species should share traits that promote susceptibility. Identifying these traits can help diagnose potential causes and thus help to direct conservation actions. Using logistic regression, we quantified the vulnerability of amphibian populations in four areas in Central America. We analyzed a species-specific database of taxonomic identity, geographic and elevational range, elevational distribution, adult and larval habitat, activity period, and maximum adult body size. We found that ( 1 ) all four sites exhibited the same pattern of decline ( there were no interactions between site and other variables ); ( 2 ) declining populations shared aquatic habitats, restricted elevational ranges, and large body sizes; and ( 3 ) there was an interaction between body size and elevational range. The most significant variable in the model was lifetime aquatic index, a factor unrelated to demographic vulnerability and one that therefore might indicate the potential causative agent( s ). Our results provide a predictive model with which to assess potential causes of population declines in other areas, and we generated a list of 52 species predicted to decline at a currently unaffected site in central Panama.

Countryside Biogeography of Neotropical Mammals: Conservation Opportunities in Agricultural Landscapes of Costa Rica

Abstract: The future of mammalian diversity in the tropics depends largely on the conservation value of human-dominated lands. We investigated the distribution of non-flying mammals in five habitats of southern Costa Rica: relatively extensive forest (227 ha), coffee plantation, pasture, coffee with adjacent forest remnant ( 5 km from relatively extensive forest, at least over the 40 years since forest clearance. Moreover, if hunting ceased, we expect that at least one of the locally extinct species could be reestablished in the existing landscape. Thus, there is an important opportunity to maintain and restore the diversity, abundance, and ecosystem roles of mammals in at least some human-dominated regions of the Neotropics.

An Evolutionary Approach to Understanding the Biology of Invasions: Local Adaptation and General-Purpose Genotypes in the Weed Verbascum thapsus

Abstract: The role of evolution in the invasion of non-native species has important implications for conser- vation, weed science, risk assessment, and policy. In this paper we first discuss why an evolutionary perspec- tive can be helpful and outline a range of potentially useful approaches from population biology and ecolog- ical genetics. As a case study, we then ask how adaptation and genetic structure may promote or constrain the expansion of an invasive weed, Verbascum thapsus , into high elevations in the Sierra Nevada of Califor- nia. We used growth-chamber and common-garden experiments to assay a range of morphological and phys- iological traits that could influence plant fitness at high elevation. There was a significant relationship be- tween elevation and leaf size and reflectance above 800 m, although we found no relationship between elevation and most other traits ( growth rate in warm or cool temperatures, freezing tolerance when grown in warm or cool temperatures, leaf number, rosette morphology, plant height ). We did see marked genetic dif- ferentiation among populations, possibly reflecting founder effects and a history of genetic drift. When we partitioned the phenotypic variance, there was almost no variation among maternal families within popula- tions, limiting the potential for selection to act. The majority of the variance for all traits was among individ- uals within families, suggesting that environmental conditions strongly influenced the phenotype. Overall, the increasing success of V. thapsus at high elevations appears to conform more to Baker's concept of a gen- eral-purpose genotype than to invasion by rapid adaptation.

Mexico's Community-Managed Forests as a Global Model for Sustainable Landscapes

Abstract: Researchers concerned with sustainable management of forests in the tropics have argued that the road to improved stewardship of forest resources is the transfer of responsibility to the local communities who get their livelihoods from them. On the other hand, conservationists have declared that the only way to stem the tide of deforestation is to place as many tracts as possible under strict protection. In this context, Mexico presents a national laboratory for studying the social and ecological benefits of delivering forests to local people. As a little-noticed result of the Mexican Revolution in the second decade of the twentieth century, well over half of the forests of Mexico were placed in community-held lands. In historic struggles that passed through several phases, most of these communities have now gained substantial control over the use of their forests. Because of the substantial degree of social capital in rural forms of organization in Mexico, this con- trol of forest resources has led to an estimated 290-479 community forest enterprises (CFEs), through which communities are producing timber on their own lands. New studies are beginning to suggest that important gains in both social and economic justice, good forest management, and biodiversity protection are resulting from the actions of these CFEs. As more forests globally are being devolved to local communities, it is important to carry out more research on the Mexican model of community forest management for timber production.

Effects of Tour Boats on the Behavior of Bottlenose Dolphins: Using Markov Chains to Model Anthropogenic Impacts

Abstract: : Nature-based tourism activities have been developing over the last decade, but it is still difficult to manage these activities sustainably. This sector is increasingly focusing on whales and dolphins in coastal communities, but the exact effects of these tourism activities are unclear. Markov chain modeling may help researchers assess the effects of tourism activities on the behavioral budget of small cetaceans. Matrix models have been used widely in population ecology to provide successful management guidelines. From June 2000 to August 2001, I collected information on the behavioral state of bottlenose dolphin ( Tursiops spp.) schools from a population residing in Doubtful Sound, Fiordland, New Zealand. In addition, I recorded the occurrence of boat and dolphin interactions. I then calculated the transition probabilities of passing from one behavior to another by using a first-order, time-discrete Markov chain model. Behavioral transitions during which a boat-dolphin interaction occurred were compiled in an “impact” chain. All other transitions were tallied in a control chain. I then quantified the effect of boat-dolphin interactions during behavioral transitions by comparing the behavioral transition probabilities of both chains. Socializing and resting behaviors were disrupted by interactions with boats to a level that raises concern. Both the duration of bouts and the total amount of time spent in both these behavioral states were substantially decreased. Dolphins were significantly more likely to be traveling after an interaction with a boat. However, the overall behavioral budget of the population was not significantly affected. Therefore, the bottlenose dolphin population seems to be able to sustain the present level of boat interactions because of its low intensity. More effort is needed to develop prognosis analyses in order to understand how the effect of boat interactions on dolphins changes with variations in intensity.

Importance of habitat area and landscape context for species richness of bees and wasps in fragmented orchard meadows

Abstract: I investigated how habitat area, habitat connectivity, and landscape context affect the species rich- ness and abundance of trap-nesting bees, wasps, and their natural enemies. The research was done on 45 or- chard meadows ranging in size from 0.08 to 5.8 ha and differing in habitat connectivity and the surrounding landscape matrix. Effects of the surrounding landscape matrix were restricted to circles with a radius of 250 m. Only the species richness of natural enemies increased with landscape diversity in the surrounding matrix. Pop- ulation densities of bees increased with habitat connectivity. Total species richness and species richness of bees, eumenid wasps, and natural enemies significantly increased with habitat area. Significant species-area rela- tionships existed for insect groups but not for plants, thereby confirming the hypothesis that higher trophic levels are more affected by habitat fragmentation than lower trophic levels. The slope of species-area relationships was steeper for mutualistic bees than for predatory wasps and natural enemies. In contrast to expectations, the rate of parasitism did not depend on habitat area but only on the local and regional abundance of hosts. My results suggest that the area and connectivity of habitat fragments is most important for the conservation of habitat specialists, whereas generalists may profit from a diverse surrounding landscape matrix.

Deforestation Trends in a Tropical Landscape and Implications for Endangered Large Mammals

Abstract: The remarkable large-mammal fauna of the Indonesian island of Sumatra is one of the most endangered on Earth and is threatened by rampant deforestation. We used remote sensing and biological surveys to study the effects of deforestation on populations of endangered large mammals in a Sumatran landscape. We measured forest loss and created a predictive model of deforestation for Bukit Barisan Selatan National Park and an unprotected buffer area based on satellite images between 1985 and 1999. We used automatic cameras to determine the distribution and relative abundance of tigers ( Panthera tigris sumatrae ), elephants ( Elephas maximus ), rhinoceros ( Dicerorhinus sumatrensis ), and tapirs ( Tapir indicus ). Between 1985 and 1999, forest loss within the park averaged 2% per year. A total of 661 km 2 of forest disappeared inside the park, and 318 km 2 were lost in a 10-km buffer, eliminating forest outside the park. Lowland forest disappeared faster than hill/montane forest ( by a factor of 6 ) and forests on gentle slopes disappeared faster than forests on steep slopes ( by a factor of 16 ). Most forest conversion resulted from agricultural development, leading to predictions that by 2010 70% of the park will be in agriculture and that by 2036 lowland forest habitat will be eliminated. Camera-trap data indicated avoidance of forest boundaries by tigers, rhinoceroses ( up to 2 km ), and elephants ( up to 3 km ). Classification of forest into core and peripheral forest based on mammal distribution suggests that, by 2010, core forest area for tigers and rhinoceros will be fragmented and reduced to 20% of remaining forest. Core forest area for elephants will be reduced to 0.5% of remaining forest. Halting forest loss has proven one of the most difficult and complex problems faced by Indonesia's conservation agencies today and will require a mix of enforcement, wise land-use strategies, increased education, capacity to manage, and new financing mechanisms.

The Role of Incentive Programs in Conserving the Snow Leopard

Abstract: Pastoralists and their livestock share much of the habitat of the snow leopard ( Uncia uncia) across south and central Asia. The levels of livestock predation by the snow leopard and other carnivores are high, and retaliatory killing by the herders is a direct threat to carnivore populations. Depletion of wild prey by poaching and competition from livestock also poses an indirect threat to the region's carnivores. Conservationists working in these underdeveloped areas that face serious economic damage from livestock losses have turned to incentive programs to motivate local communities to protect carnivores. We describe a pilot incentive program in India that aims to offset losses due to livestock predation and to enhance wild prey density by creating livestock-free areas on common land. We also describe how income generation from handicrafts in Mongolia is helping curtail poaching and retaliatory killing of snow leopards. However, initiatives to offset the costs of living with carnivores and to make conservation beneficial to affected people have thus far been small, isolated, and heavily subsidized. Making these initiatives more comprehensive, expanding their coverage, and internalizing their costs are future challenges for the conservation of large carnivores such as the snow leopard.

The Use of Bayesian Model Averaging to Better Represent Uncertainty in Ecological Models

Abstract: : In conservation biology, uncertainty about the choice of a statistical model is rarely considered. Model-selection uncertainty occurs whenever one model is chosen over plausible alternative models to represent understanding about a process and to make predictions about future observations. The standard approach to representing prediction uncertainty involves the calculation of prediction (or confidence) intervals that incorporate uncertainty about parameter estimates contingent on the choice of a “best” model chosen to represent truth. However, this approach to prediction based on statistical models tends to ignore model-selection uncertainty, resulting in overconfident predictions. Bayesian model averaging (BMA) has been promoted in a range of disciplines as a simple means of incorporating model-selection uncertainty into statistical inference and prediction. Bayesian model averaging also provides a formal framework for incorporating prior knowledge about the process being modeled. We provide an example of the application of BMA in modeling and predicting the spatial distribution of an arboreal marsupial in the Eden region of southeastern Australia. Other approaches to estimating prediction uncertainty are discussed. Resumen: La incertidumbre acerca de la eleccion de un modelo estadistico es raramente considerada en biologia de la conservacion. La incertidumbre de seleccion de modelo ocurre cuando se selecciona un modelo entre otros posibles modelos alternativos para representar el entendimiento de un proceso y para hacer predicciones acerca de observaciones futuras. El metodo estandar para representar la incertidumbre de predicciones implica el calculo de intervalos de prediccion (o confianza) que incorporan la incertidumbre en estimaciones de parametros dependiendo de la seleccion de un modelo “mejor” seleccionado para representar la verdad. Sin embargo, este metodo de prediccion basado en modelos estadisticos tiende a ignorar la incertidumbre de seleccion de modelo, lo que resulta en predicciones demasiado confiadas. El promedio de modelo Bayesiano (PMB) ha sido promovido en varias disciplinas como un medio simplificado para incorporar la incertidumbre de seleccion de modelo en la inferencia y prediccion estadistica. El PMB tambien proporciona un marco formal para la incorporacion de conocimiento previo acerca del proceso a modelar. Proporcionamos un ejemplo de la aplicacion de PMB en el modelado y predecimos la distribucion espacial de un marsupial arboreo en la region Eden del sureste de Australia. Se discuten otros metodos para estimar la incertidumbre de prediccion.

Impacts of the brown tree snake: Patterns of decline and species persistence in Guam's avifauna

Abstract: Predation by brown tree snakes ( Boiga irregularis ) devastated the avifauna of Guam in the Mari- ana Islands during the last half of the twentieth century, causing the extirpation or serious reduction of most of the island's 25 resident bird species. Past studies have provided qualitative descriptions of the decline of na- tive forest birds but have not considered all species or presented quantitative analyses. We analyzed two sets of survey data gathered in northern Guam between 1976 and 1998 and reviewed unpublished sources to provide a comprehensive account of the impact of brown tree snakes on the island's birds. Our results indi- cate that 22 species, including 17 of 18 native species, were severely affected by snakes. Twelve species were likely extirpated as breeding residents on the main island, 8 others experienced declines of � 90% throughout the island or at least in the north, and 2 were kept at reduced population levels during all or much of the study. Declines of � 90% occurred rapidly, averaging just 8.9 years along three roadside survey routes com- bined and 1.6 years at a 100-ha forested study site. Declines in northern Guam were also relatively synchro- nous and occurred from about 1976 to 1986 for most species. The most important factor predisposing a spe- cies to coexistence with brown tree snakes was its ability to nest and roost at locations where snakes were uncommon. Large clutch size and large body size were also related to longer persistence times, although large body size appeared to delay, but not prevent, extirpation. Our results draw attention to the enormous detri- mental impact that brown tree snakes are likely to have upon invading new areas. Increased containment ef- forts on Guam are needed to prevent further colonizations, but a variety of additional management efforts would also benefit the island's remaining bird populations.

Effects of Forest Roads on Understory Plants in a Managed Hardwood Landscape

Abstract: The effect of forest roads on species distribution and dispersal is an important conservation and management issue. We examined distributions of understory plants and their relationships to unpaved forest roads in a northern hardwood landscape in the Chequamegon National Forest, Wisconsin (U.S.A.). At six dif- ferent sites, we recorded species cover, canopy cover, litter depth and cover, and bare ground at 11 distances (0, 5, 10, 15, 20, 30, 45, 60, 90, 120, and 150 m) from the road edge. At each of the 11 distances, we estab- lished a 60-m transect parallel to the road edge, within which we sampled 10 randomly placed 1 � 1 m plots (660 plots). We examined changes in species abundance (percent species cover per plot), richness, and Shan- non-Wiener diversity ( H � ) with distance from the roads in an effort to determine the degree and magnitude of road effects on plant distribution. The species richness and Hof native plants and the abundance of exotic species were clearly related to distance from the roads. Exotic species were most prevalent within 15 m of roads, occurring infrequently in the interior forest. The richness and Hof native species were lower on the roadsides but reached interior-forest levels within a short distance (5 m) from the roads. The roads appeared to be associated with a disturbance corridor that affected site variables up to 15 m into the hardwood stands. At our six sites we detected 117 species, 25% of which occurred more frequently near the road, with only 12% having a 90% or greater preference for the forest interior. Our results suggest that roads have associated ef- fects that alter interior-forest conditions and thus plant species composition and abundance; however, these effects are limited in depth of penetration into managed forests.

Individual, Population, Community, and Ecosystem Consequences of a Fish Invader in New Zealand Streams

Abstract: Knowledge of the population biology of invading species will often be necessary to develop effective management procedures and policies. But because invaders can have unexpected indirect effects in food webs, invasion ecologists need to integrate processes at the population level and other ecological levels. I de- scribe a series of coordinated studies in New Zealand streams that address the effect of an exotic fish on indi- vidual behavior, population, community, and ecosystem patterns. Such case studies are important as an aid to the formulation of policy about invasions that are especially likely to become problematic. At the individ- ual level, grazing invertebrates showed changes in behavior as a result of the introduction of brown trout ( Salmo trutta ), a predator that exerts a very different selection pressure than do native fish. At the population level, trout have replaced nonmigratory galaxiid fish in some streams but not others, and have affected the distributions of crayfish and other large invertebrates. At the community level, trout have suppressed grazing pressure from invertebrates and are thus responsible for enhancing algal biomass and changing algal species composition. Finally, at the ecosystem level, essentially all annual production of invertebrates is consumed by trout (but not by galaxiids), and algal primary productivity is six times higher in a trout stream. This leads, in turn, to an increased flux of nutrients from the water to the benthic community. The trout invasion has led to strong top-down control of community structure and ecosystem functioning via its effects on individual be- havior and population distribution and abundance. Particular physiological, behavioral, and demographic traits of invaders can lead to profound ecosystem consequences that managers need to take into account.

Impact of Forest Fragmentation on Understory Plant Species Richness in Amazonia

Abstract: Forest fragmentation in the tropics severely affects large trees, but its effect on other life stages and plant life forms is poorly understood. In Central Amazonia, 9 to 19 years after fragmentation, we recorded species richness and net seedling recruitment rate in forest fragments of 1, 10, and 100 ha and in continuous forest. In 1991 all seedlings 5–100 cm tall within permanent 1-m2 plots in fragments and continuous forest were counted and grouped into tree, liana, palm, and herb life-form classes. In 1993 we manually removed all seedlings that were <1 m tall from the permanent plots. Six years and 5 months later ( 1999 ), all new seedlings recruited into the plots were counted, grouped into different life forms, and classified into distinct morphospecies. The species richness of recruited tree, liana, herb, and palm seedlings was lower in forest fragments than in continuous forest, with the 1-ha fragment having the poorest species richness. The total number of recruited individuals was 40% less than that previously present for all life forms, except lianas. Liana recruitment was 7% to 500% higher than the original abundance in the forest fragments and continuous forest. In general, species similarity was higher among fragments than between fragments and continuous forest, with the 1-ha fragment being less similar. Species rank/abundance curves showed that continuous forest species in all life forms tended to disappear in forest fragments, whereas common species in forest fragments were absent from continuous forest. Overall, our results suggest that the life-form composition and structure of the regenerative plant pool in fragments were shifting toward a species-poor seedling community. Losses of understory species diversity, but especially of tree seedlings, threaten the maintenance of rainforest biodiversity and compromise future forest regeneration. Resumen: La fragmentacion de las selvas tropicales afecta severamente a a los arboles de gran porte, sin embargo, su efecto sobre otros estadios y formas de vida de las plantas es poco conocido. En la Amazonia central, de 9 a 19 anos despues de la fragmentacion, se registro la riqueza de especies y la tasa neta de reclutamiento de plantulas en fragmentos de selva de 1, 10, y 100 ha y en selva continua. En 1991, todas las plantulas de 5–100 cm de altura dentro de cuadrantes permanentes de 1-m2 en los fragmentos y en la selva continua, fueron contadas y agrupadas en diferentes formas de vida: arboles, lianas, palmas y hierbas. En 1993 se removieron manualmente todas las plantulas <1 m de altura dentro de los cuadrantes. Seis anos y cinco meses mas tarde (1999) se contaron todas las plantulas reclutadas dentro de los cuadrantes, se agruparon en diferentes formas de vida v se clasificaron en morfoespecies distintivas. La riqueza de especies de plantulas reclutadas en todas las formas de vida fue menor en los fragmentos que en la selva continua, con el fragmento de 1 ha presentando la menor riqueza de especies. El numero total de individuos reclutados fue 40% menor que los previamente presentes para todas las formas de vida, excepto lianas. El reclutamiento de lianas fue de 7 a 500% mayor que la abundancia original en los fragmentos y en la selva continua. En general la similitud de especies fue mayor entre fragmentos que entre fragmentos y selva continua, con el fragmento de 1-ha siendo el menos similar. Las curvas de rango/abundancia de especies, mostraron que las especies de selva continua en todas las formas de vida tendieron a desaparecer de los fragmentos, mientras que las especies comunes en los fragmentos estuvieron ausentes en la selva continua. En general, nuestros resultados sugieren que la composicion de formas de vida y la estructura del banco regenerativo en fragmentos tienden a convertirse en una comunidad de plantulas pobre en especies. La perdida de diversidad de especies del sotobosque, pero especialmente de plantulas de arboles, amenaza el mantenimiento de la biodiversidad y pone en peligro la regeneracion futura de la selva.