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‣ Determinantes ecológicos do risco de extinção: abundância local, amplitude de nicho, capacidade de dispersão e a resposta das espécies de pequenos mamíferos à fragmentação florestal no Planalto Atlântico Paulista; Ecological determinants of extinction risk: local abundance, niche breadth, dispersal ability and response of small mammals to forest fragmentation at the Atlantic Plateau of São Paulo

Martins, Thais Kubik
Fonte: Biblioteca Digitais de Teses e Dissertações da USP Publicador: Biblioteca Digitais de Teses e Dissertações da USP
Tipo: Dissertação de Mestrado Formato: application/pdf
Publicado em 25/11/2011 Português
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Alterações antrópicas nos ecossistemas, em especial a perda e a fragmentação de habitat, são consideradas as principais causas do grande aumento nas extinções de espécies nas últimas décadas. Uma vez que o risco de extinção varia grandemente entre as espécies, os determinantes ecológicos associados à chance de extinção têm sido um tema central e muito debatido na literatura ecológica. Atributos ecológicos relacionados à raridade, como amplitude de nicho e abundância local, e a capacidade de dispersão são recorrentemente citados na literatura como determinantes do risco de extinção local. A partir de dados de ocorrência em fragmentos, matas contínuas e áreas de agricultura, e de captura-recaptura em três grades de 2 ha em mata continua, no Planalto Atlântico Paulista, investigamos o efeito desses três atributos ecológicos sobre o risco de extinção local em espécies de pequenos mamíferos. Utilizamos a abordagem de seleções de modelos e o critério de Akaike (AICc) para avaliar qual das hipóteses existentes na literatura sobre a relação destes atributos com o risco de extinção é mais plausível. Foram realizadas duas seleções de modelos: uma considerando os três atributos para sete espécies; e outra considerando apenas a amplitude de nicho e abundância local para 18 espécies. Os resultados de ambas as seleções indicam a amplitude de nicho como determinante principal do risco de extinção local...

‣ Body size and extinction risk in Brazilian carnivores

Forero-Medina,German; Vieira,Marcus Vinícius; Grelle,Carlos Eduardo de Viveiros; Almeida,Paulo Jose
Fonte: Instituto Virtual da Biodiversidade | BIOTA - FAPESP Publicador: Instituto Virtual da Biodiversidade | BIOTA - FAPESP
Tipo: Artigo de Revista Científica Formato: text/html
Publicado em 01/06/2009 Português
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Because extinctions are not random across taxa, it is important for conservation biologists to identify the traits that make some species more vulnerable. Factors associated with vulnerability include small geographical ranges, low densities, high trophic level, "slow" life histories, body size, and tolerance to altered habitats. In this study we examined the relationship of body size, reproductive output, longevity, and extinction risk for carnivores occurring in Brazil. We used generalized linear models analyses on phylogenetically independent contrasts to test the effect of body size alone, and the combined effect of body size, litter size and longevity on extinction risk. Body size appeared in the two best models according to the selection criteria (AIC), and it was the most plausible bionomic variable associated with extinction risk. Litter size and longevity, bionomic traits previously associated with threat risk of Brazilian carnivores, were implausible. The higher extinction risk for larger species could result from body size influencing vulnerability to different human activities, such as killing, habitat destruction and fragmentation, and the small size of natural reserves.

‣ The Perils of Picky Eating: Dietary Breadth Is Related to Extinction Risk in Insectivorous Bats

Boyles, Justin G.; Storm, Jonathan J.
Fonte: Public Library of Science Publicador: Public Library of Science
Tipo: Artigo de Revista Científica
Publicado em 25/07/2007 Português
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Several recent papers evaluate the relationship between ecological characteristics and extinction risk in bats. These studies report that extinction risk is negatively related to geographic range size and positively related to habitat specialization. Here, we evaluate the hypothesis that extinction risk is also related to dietary specialization in insectivorous vespertilionid bats using both traditional and phylogenetically-controlled analysis of variance. We collected dietary data and The World Conservation Union (IUCN) rankings for 44 Australian, European, and North American bat species. Our results indicate that species of conservation concern (IUCN ranking near threatened or above) are more likely to have a specialized diet than are species of least concern. Additional analyses show that dietary breadth is not correlated to geographic range size or wing morphology, characteristics previously found to correlate with extinction risk. Therefore, there is likely a direct relationship between dietary specialization and extinction risk; however, the large variation in dietary breadth within species of least concern suggests that diet alone cannot explain extinction risk. Our results may have important implications for the development of predictive models of extinction risk and for the assignment of extinction risk to insectivorous bat species. Similar analyses should be conducted on additional bat families to assess the generality of this relationship between niche breadth and extinction risk.

‣ Direct and indirect effects of biological factors on extinction risk in fossil bivalves

Harnik, Paul G.
Fonte: National Academy of Sciences Publicador: National Academy of Sciences
Tipo: Artigo de Revista Científica
Português
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Biological factors, such as abundance and body size, may contribute directly to extinction risk and indirectly through their influence on other biological characteristics, such as geographic range size. Paleontological data can be used to explicitly test many of these hypothesized relationships, and general patterns revealed through analysis of the fossil record can help refine predictive models of extinction risk developed for extant species. Here, I use structural equation modeling to tease apart the contributions of three canonical predictors of extinction—abundance, body size, and geographic range size—to the duration of bivalve species in the early Cenozoic marine fossil record of the eastern United States. I find that geographic range size has a strong direct effect on extinction risk and that an apparent direct effect of abundance can be explained entirely by its covariation with geographic range. The influence of geographic range on extinction risk is manifest across three ecologically disparate bivalve clades. Body size also has strong direct effects on extinction risk but operates in opposing directions in different clades, and thus, it seems to be decoupled from extinction risk in bivalves as a whole. Although abundance does not directly predict extinction risk...

‣ Long-term differences in extinction risk among the seven forms of rarity

Harnik, Paul G.; Simpson, Carl; Payne, Jonathan L.
Fonte: The Royal Society Publicador: The Royal Society
Tipo: Artigo de Revista Científica
Português
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Rarity is widely used to predict the vulnerability of species to extinction. Species can be rare in markedly different ways, but the relative impacts of these different forms of rarity on extinction risk are poorly known and cannot be determined through observations of species that are not yet extinct. The fossil record provides a valuable archive with which we can directly determine which aspects of rarity lead to the greatest risk. Previous palaeontological analyses confirm that rarity is associated with extinction risk, but the relative contributions of different types of rarity to extinction risk remain unknown because their impacts have never been examined simultaneously. Here, we analyse a global database of fossil marine animals spanning the past 500 million years, examining differential extinction with respect to multiple rarity types within each geological stage. We observe systematic differences in extinction risk over time among marine genera classified according to their rarity. Geographic range played a primary role in determining extinction, and habitat breadth a secondary role, whereas local abundance had little effect. These results suggest that current reductions in geographic range size will lead to pronounced increases in long-term extinction risk even if local populations are relatively large at present.

‣ Phylogenetic correlates of extinction risk in mammals: species in older lineages are not at greater risk

Verde Arregoitia, Luis Darcy; Blomberg, Simon P.; Fisher, Diana O.
Fonte: The Royal Society Publicador: The Royal Society
Tipo: Artigo de Revista Científica
Publicado em 22/08/2013 Português
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Phylogenetic information is becoming a recognized basis for evaluating conservation priorities, but associations between extinction risk and properties of a phylogeny such as diversification rates and phylogenetic lineage ages remain unclear. Limited taxon-specific analyses suggest that species in older lineages are at greater risk. We calculate quantitative properties of the mammalian phylogeny and model extinction risk as an ordinal index based on International Union for Conservation of Nature Red List categories. We test for associations between lineage age, clade size, evolutionary distinctiveness and extinction risk for 3308 species of terrestrial mammals. We show no significant global or regional associations, and three significant relationships within taxonomic groups. Extinction risk increases for evolutionarily distinctive primates and decreases with lineage age when lemurs are excluded. Lagomorph species (rabbits, hares and pikas) that have more close relatives are less threatened. We examine the relationship between net diversification rates and extinction risk for 173 genera and find no pattern. We conclude that despite being under-represented in the frequency distribution of lineage ages, species in older, slower evolving and distinct lineages are not more threatened or extinction-prone. Their extinction...

‣ Drivers of extinction risk in African mammals: the interplay of distribution state, human pressure, conservation response and species biology

Di Marco, Moreno; Buchanan, Graeme M.; Szantoi, Zoltan; Holmgren, Milena; Grottolo Marasini, Gabriele; Gross, Dorit; Tranquilli, Sandra; Boitani, Luigi; Rondinini, Carlo
Fonte: The Royal Society Publicador: The Royal Society
Tipo: Artigo de Revista Científica
Publicado em 26/05/2014 Português
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Although conservation intervention has reversed the decline of some species, our success is outweighed by a much larger number of species moving towards extinction. Extinction risk modelling can identify correlates of risk and species not yet recognized to be threatened. Here, we use machine learning models to identify correlates of extinction risk in African terrestrial mammals using a set of variables belonging to four classes: species distribution state, human pressures, conservation response and species biology. We derived information on distribution state and human pressure from satellite-borne imagery. Variables in all four classes were identified as important predictors of extinction risk, and interactions were observed among variables in different classes (e.g. level of protection, human threats, species distribution ranges). Species biology had a key role in mediating the effect of external variables. The model was 90% accurate in classifying extinction risk status of species, but in a few cases the observed and modelled extinction risk mismatched. Species in this condition might suffer from an incorrect classification of extinction risk (hence require reassessment). An increased availability of satellite imagery combined with improved resolution and classification accuracy of the resulting maps will play a progressively greater role in conservation monitoring.

‣ Primate Extinction Risk and Historical Patterns of Speciation and Extinction in Relation to Body Mass

Matthews, Luke J.; Arnold, Christian; Machanda, Zarin Pearl; Nunn, Charles Lindsay
Fonte: Royal Society of London Publicador: Royal Society of London
Tipo: Artigo de Revista Científica
Português
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Body mass is thought to influence diversification rates, but previous studies have produced ambiguous results. We investigated patterns of diversification across 100 trees obtained from a new Bayesian inference of primate phylogeny that sampled trees in proportion to their posterior probabilities. First, we used simulations to assess the validity of previous studies that used linear models to investigate the links between IUCN Red List status and body mass. These analyses support the use of linear models for ordinal ranked data on threat status, and phylogenetic generalized linear models revealed a significant positive correlation between current extinction risk and body mass across our tree block. We then investigated historical patterns of speciation and extinction rates using a recently developed maximum-likelihood method. Specifically, we predicted that body mass correlates positively with extinction rate because larger bodied organisms reproduce more slowly, and body mass correlates negatively with speciation rate because smaller bodied organisms are better able to partition niche space. We failed to find evidence that extinction rates covary with body mass across primate phylogeny. Similarly, the speciation rate was generally unrelated to body mass...

‣ Multi-model climate projections for biodiversity risk assessments

Fordham, D.; Wigley, T.; Brook, B.
Fonte: Ecological Soc Amer Publicador: Ecological Soc Amer
Tipo: Artigo de Revista Científica
Publicado em //2011 Português
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Species distribution models, linked to climate projections, are widely used in extinction-risk assessment and conservation planning. However, the degree of confidence that we can place on future climate-change projections depends on global climate-model performance and involves uncertainties that need to be assessed rigorously via climate-model evaluation. Performance assessments are important because the choice of climate model influences projections of species’ range movement and extinction risk. A consensus view from the climate modeling community is that no single climate model is superior in its ability to forecast key climatic features. Despite this, the advantages of using multi-model ensemble averaged climate forecasts to account for climate-model uncertainties have not been recognized by ecologists. Here we propose a method to use a range of skill and convergence metrics to rank commonly used atmosphere–ocean general circulation models (AOGCMs) according to their skill in reproducing 20-year observed patterns of regional and global climates of interest, and to assess their consistency with other AOGCMs. By eliminating poorly performing models and averaging the remainder with equal weights, we show how downscaled annual multi-climate-model ensemble-averaged forecasts...

‣ Reconstructing past species assemblages reveals the changing patterns and drivers of extinction through time

Bromham, L.; Lanfear, R.; Cassey, P.; Gibb, G.; Cardillo, M.
Fonte: Royal Soc London Publicador: Royal Soc London
Tipo: Artigo de Revista Científica
Publicado em //2012 Português
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Predicting future species extinctions from patterns of past extinctions or current threat status relies on the assumption that the taxonomic and biological selectivity of extinction is consistent through time. If the driving forces of extinction change through time, this assumption may be unrealistic. Testing the consistency of extinction patterns between the past and the present has been difficult, because the phylogenetically explicit methods used to model present-day extinction risk typically cannot be applied to the data from the fossil record. However, the detailed historical and fossil records of the New Zealand avifauna provide a unique opportunity to reconstruct a complete, large faunal assemblage for different periods in the past. Using the first complete phylogeny of all known native New Zealand bird species, both extant and extinct, we show how the taxonomic and phylogenetic selectivity of extinction, and biological correlates of extinction, change from the pre-human period through Polynesian and European occupation, to the present. These changes can be explained both by changes in primary threatening processes, and by the operation of extinction filter effects. The variable patterns of extinction through time may confound attempts to identify risk factors that apply across time periods...

‣ Drivers of extinction risk in African mammals: the interplay of distribution state, human pressure, conservation response and species biology

DI MARCO Moreno; BUCHANAN Graeme, M.; SZANTOI ZOLTAN; HOLMGREN Milena; GROTTOLO MARASINI Gabriele; GROSS DORIT; TRANQUILLI Sandra; BOITANI Luigi; RONDININI Carlo
Fonte: ROYAL SOC Publicador: ROYAL SOC
Tipo: Articles in Journals Formato: Online
Português
Relevância na Pesquisa
47.73914%
Although conservation intervention has reversed the decline of some species, our success is outweighed by a much larger number of species moving towards extinction. Extinction risk modelling can identify correlates of risk and species not yet recognized to be threatened. Here, we use machine learning models to identify correlates of extinction risk in African terrestrial mammals using a set of variables belonging to four classes: species distribution state, human pressures, conservation response and species biology. We derived information on distribution state and human pressure from satellite- borne imagery. Variables in all four classes were identified as important predictors of extinction risk, and interactions were observed among variables in different classes (e.g. level of protection, human threats, species distribution ranges). Species biology had a key role in mediating the effect of external variables. The model was 90% accurate in classifying extinction risk status of species, but in a few cases the observed and modelled extinction risk mismatched. Species in this condition might suffer from an incorrect classification of extinction risk (hence require reassessment). An increased availability of satellite imagery combined with improved resolution and classification accuracy of the resulting maps will play a progressively greater role in conservation monitoring.; JRC.H.5-Land Resources Management

‣ Extinction risk scales better to generations than to years

O'Grady, J.; Reed, D.; Brook, B.; Frankham, R.
Fonte: Cambridge Univ Press Publicador: Cambridge Univ Press
Tipo: Artigo de Revista Científica
Publicado em //2008 Português
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It is critical to search for, and to apply, robust generalizations in conservation biology as species-specific data on endangered species are often limited. While generalizations are common in conservation genetics, where processes are treated on the scale of generations, the unique population dynamics of species are often stressed in ecology and conservation management. Is the apparent uniqueness of population attributes partly an artefact of measurement scale? One facet of this debate is the question of whether extinction risk scales better to years or to generations. To resolve this issue, the extinction risk of 100 well-studied vertebrate taxa was estimated using stochastic computer projections and analyses conducted to determine whether risk related better to years or generations. Relative strengths of evidence for alternative hypotheses were assessed using information theory. Extinction risk, assessed as the population size required for a 90% probability of persistence for 100 years, was strongly related to generation length. Conversely, when extinction risk was assessed for a fixed number of generations, there was no support for a relationship between risk and years. This finding has ramifications for assessing and reporting extinction risk because it shows that (1) crucial signals for the effective management of threatened species may not be detected when risk is measured on a scale of years alone; (2) correcting for generation length will allow data from a wider range of species to be used as defaults for species with limited data; (3) generational-scale tests of factors affecting extinction risk are more powerful than year-based ones. We recommend that extinction risk be routinely reported on a generational scale...

‣ Minimum viable puoulation sizes and global extinction risk are unrelated

Brook, B.; Traill, L.; Bradshaw, C.
Fonte: Blackwell Publishing Ltd Publicador: Blackwell Publishing Ltd
Tipo: Artigo de Revista Científica
Publicado em //2006 Português
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Theoretical and empirical work has shown that once reduced in size and geographical range, species face a considerably elevated risk of extinction. We predict minimum viable population sizes (MVP) for 1198 species based on long-term time-series data and model-averaged population dynamics simulations. The median MVP estimate was 1377 individuals (90% probability of persistence over 100 years) but the overall distribution was wide and strongly positively skewed. Factors commonly cited as correlating with extinction risk failed to predict MVP but were able to predict successfully the probability of World Conservation Union Listing. MVPs were most strongly related to local environmental variation rather than a species' intrinsic ecological and life history attributes. Further, the large variation in MVP across species is unrelated to (or at least dwarfed by) the anthropogenic threats that drive the global biodiversity crisis by causing once-abundant species to decline; Barry W. Brook, Lochran W. Traill and Corey J. A. Bradshaw; The definitive version is available at www.blackwell-synergy.com

‣ Correlations among Extinction Risks Assessed by Different Systems of Threatened Species Categorization

Master, L.; O'Grady, J.; Burgman, M.; Keith, D.; Andelman, S.; Brook, B.; Hammerson, G.; Regan, H.; Frankham, R.
Fonte: Blackwell Publishing Inc Publicador: Blackwell Publishing Inc
Tipo: Artigo de Revista Científica
Publicado em //2004 Português
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Many different systems are used to assess levels of threat faced by species. Prominent ones are those used by the World Conservation Union, NatureServe, and the Florida Game and Freshwater Fish Commission (now the Florida Fish and Wildlife Conservation Commission). These systems assign taxa a threat ranking by assessing their demographic and ecological characteristics. These threat rankings support the legislative protection of species and guide the placement of conservation programs in order of priority. It is not known, however, whether these assessment systems rank species in a similar order. To resolve this issue, we assessed 55 mainly vertebrate taxa with widely differing life histories under each of these systems and determined the rank correlations among them. Moderate, significant positive correlations were seen among the threat rankings provided by the three systems (correlations 0.58–0.69). Further, the threat rankings for taxa obtained using these systems were significantly correlated to their rankings based on predicted probability of extinction within 100 years as determined by population viability analysis (correlations 0.28–0.37). The different categorization systems, then, yield related but not identical threat rankings...

‣ Human population density and extinction risk in the world's carnivores

Cardillo, Marcel; Purvis, Andy; Sechrest, Wes; Gittleman, John L.; Bielby, Jon; Mace, Georgina M.
Fonte: Public Library of Science Publicador: Public Library of Science
Tipo: Artigo de Revista Científica Formato: 6 pages
Português
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Understanding why some species are at high risk of extinction, while others remain relatively safe, is central to the development of a predictive conservation science. Recent studies have shown that a species' extinction risk may be determined by two types of factors: intrinsic biological traits and exposure to external anthropogenic threats. However, little is known about the relative and interacting effects of intrinsic and external variables on extinction risk. Using phylogenetic comparative methods, we show that extinction risk in the mammal order Carnivora is predicted more strongly by biology than exposure to high-density human populations. However, biology interacts with human population density to determine extinction risk: biological traits explain 80% of variation in risk for carnivore species with high levels of exposure to human populations, compared to 45% for carnivores generally. The results suggest that biology will become a more critical determinant of risk as human populations expand. We demonstrate how a model predicting extinction risk from biology can be combined with projected human population density to identify species likely to move most rapidly towards extinction by the year 2030. African viverrid species are particularly likely to become threatened...

‣ Unravelling the structure of species extinction risk for predictive conservation science

Lee, Tien Ming; Jetz, Walter
Fonte: The Royal Society Publicador: The Royal Society
Tipo: Artigo de Revista Científica
Português
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Extinction risk varies across species and space owing to the combined and interactive effects of ecology/life history and geography. For predictive conservation science to be effective, large datasets and integrative models that quantify the relative importance of potential factors and separate rapidly changing from relatively static threat drivers are urgently required. Here, we integrate and map in space the relative and joint effects of key correlates of The International Union for Conservation of Nature-assessed extinction risk for 8700 living birds. Extinction risk varies significantly with species' broad-scale environmental niche, geographical range size, and life-history and ecological traits such as body size, developmental mode, primary diet and foraging height. Even at this broad scale, simple quantifications of past human encroachment across species' ranges emerge as key in predicting extinction risk, supporting the use of land-cover change projections for estimating future threat in an integrative setting. A final joint model explains much of the interspecific variation in extinction risk and provides a remarkably strong prediction of its observed global geography. Our approach unravels the species-level structure underlying geographical gradients in extinction risk and offers a means of disentangling static from changing components of current and future threat. This reconciliation of intrinsic and extrinsic...

‣ Human Population Density and Extinction Risk in the World's Carnivores

Cardillo, Marcel; Purvis, Andy; Sechrest, Wes; Gittleman, John L; Bielby, Jon; Mace, Georgina M
Fonte: Public Library of Science Publicador: Public Library of Science
Tipo: Artigo de Revista Científica
Português
Relevância na Pesquisa
47.753687%
Understanding why some species are at high risk of extinction, while others remain relatively safe, is central to the development of a predictive conservation science. Recent studies have shown that a species' extinction risk may be determined by two types of factors: intrinsic biological traits and exposure to external anthropogenic threats. However, little is known about the relative and interacting effects of intrinsic and external variables on extinction risk. Using phylogenetic comparative methods, we show that extinction risk in the mammal order Carnivora is predicted more strongly by biology than exposure to high-density human populations. However, biology interacts with human population density to determine extinction risk: biological traits explain 80% of variation in risk for carnivore species with high levels of exposure to human populations, compared to 45% for carnivores generally. The results suggest that biology will become a more critical determinant of risk as human populations expand. We demonstrate how a model predicting extinction risk from biology can be combined with projected human population density to identify species likely to move most rapidly towards extinction by the year 2030. African viverrid species are particularly likely to become threatened...

‣ The predictability of extinction: biological and external correlates of decline in mammals

Cardillo, Marcel; Mace, Georgina M; Gittleman, John L; Jones, Kate E.; Bielby, Jon; Purvis, A.
Fonte: Royal Society of London Publicador: Royal Society of London
Tipo: Artigo de Revista Científica
Português
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Extinction risk varies among species, and comparative analyses can help clarify the causes of this variation. Here we present a phylogenetic comparative analysis of species-level extinction risk across nearly the whole of the class Mammalia. Our aims were

‣ Evolution: Multiple causes of high extinction risk in large mammal species

Cardillo, Marcel; Mace, Georgina M; Jones, Kate E.; Bielby, Jon; Bininda-Emonds, Olaf R. P.; Sechrest, Wes; Orme, C. David L.; Purvis, A.
Fonte: American Association for the Advancement of Science Publicador: American Association for the Advancement of Science
Tipo: Artigo de Revista Científica
Português
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Many large animal species have a high risk of extinction. This is usually thought to result simply from the way that species traits associated with vulnerability, such as low reproductive rates, scale with body size. In a broad-scale analysis of extinctio

‣ Biological determinants of extinction risk: why are smaller species less vulnerable?

Cardillo, Marcel
Fonte: Cambridge University Press Publicador: Cambridge University Press
Tipo: Artigo de Revista Científica
Português
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It is becoming increasingly clear that species of smaller body size tend to be less vulnerable to contemporary extinction threats than larger species, but few studies have examined the mechanisms underlying this pattern. In this paper, data for the Austra