Abstract
Identifying which species are at greatest risk, what makes them vulnerable, and where they are distributed are central goals for conservation science. While knowledge of which factors influence extinction risk is increasingly available for some taxonomic groups, a deeper understanding of extinction correlates and the geography of risk remains lacking. Here, we develop a predictive random forest model using both geospatial and mammalian species’ trait data to uncover the statistical and geographic distributions of extinction correlates. We also explore how this geography of risk may change under a rapidly warming climate. We found distinctive macroecological relationships between species-level risk and extinction correlates, including the intrinsic biological traits of geographic range size, body size and taxonomy, and extrinsic geographic settings such as seasonality, habitat type, land use and human population density. Each extinction correlate exhibited ranges of values that were especially associated with risk, and the importance of different risk factors was not geographically uniform across the globe. We also found that about 10% of mammals not currently recognized as at-risk have biological traits and occur in environments that predispose them towards extinction. Southeast Asia had the most actually and potentially threatened species, underscoring the urgent need for conservation in this region. Additionally, nearly 40% of currently threatened species were predicted to experience rapid climate change at 0.5 km/year or more. Biological and environmental correlates of mammalian extinction risk exhibit distinct statistical and geographic distributions. These results provide insight into species-level patterns and processes underlying geographic variation in extinction risk. They also offer guidance for future conservation research focused on specific geographic regions, or evaluating the degree to which species-level patterns mirror spatial variation in the pressures faced by populations within the ranges of individual species. The added impacts from climate change may increase the susceptibility of at-risk species to extinction and expand the regions where mammals are most vulnerable globally.
Highlights
Human impacts are causing widespread biodiversity loss, with rates of extinction that are about 1,000 times greater than background levels [1,2,3]
Assessment of risk under the IUCN Red List of Threatened Species has only been completed for 66% of all vertebrates, of which 15% are assessed as Data Deficient (DD), lacking sufficient information to determine their conservation status [7,8]
We found that each extinction correlate exhibited distinct statistical distributions of values that were strongly associated with risk, including the points where extinction risk rises sharply (Fig 1)
Summary
Human impacts are causing widespread biodiversity loss, with rates of extinction that are about 1,000 times greater than background levels [1,2,3]. Assessment of risk under the IUCN Red List of Threatened Species has only been completed for 66% of all vertebrates, of which 15% are assessed as Data Deficient (DD), lacking sufficient information to determine their conservation status [7,8]. While factors influencing extinction risk have been identified [9,10,11], we lack systematic investigation of the geographic patterns of important risk factors in some geographic regions but not others [12,13]. Uncovering the statistical and geographic distributions of trait, environmental, and threat variables that predict species-level risk is important for understanding the underlying nature and global geographies of extinction correlates. While human land use is the major driver of species extinctions today, climate change is a growing and compounding threat, with climate zones projected to shift across ca. While human land use is the major driver of species extinctions today, climate change is a growing and compounding threat, with climate zones projected to shift across ca. 20% of the Earth’s land surface by the end of this century [14,15]
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