Geography of current and future global mammal extinction risk

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.

确定哪些物种面临最高的灭绝风险、哪些因素使其易受威胁，以及它们的地理分布范围，是保护科学的核心目标。尽管部分分类群中，关于影响灭绝风险的因素的认知已日益丰富，但学界对灭绝关联因子（extinction correlates）及其风险地理分布的深入理解仍有所欠缺。本研究利用地理空间数据与哺乳动物物种功能性状数据，构建了预测性随机森林模型（random forest model），以揭示灭绝关联因子的统计分布与地理分布格局。同时，本研究探讨了在气候快速变暖背景下，风险地理分布格局可能发生的变化。
研究发现，物种水平的灭绝风险与各类灭绝关联因子之间存在鲜明的宏观生态关联，其中既包括地理分布范围、体型大小与分类学归属等内在生物学性状，也涵盖季节动态、生境类型、土地利用方式与人口密度等外在地理环境因素。每一类灭绝关联因子都存在与风险高度相关的数值区间，且不同风险因子的重要性在全球范围内并非均匀分布。此外，本研究发现，约10%目前未被认定为受威胁的哺乳动物，其生物学性状与所处环境本就使其易于走向灭绝。
东南亚地区的实际受威胁与潜在受威胁哺乳动物物种数量最多，这凸显了该区域开展保护工作的紧迫性。此外，近40%目前已被列为受威胁的物种，预计将以每年0.5千米及以上的速率遭遇快速气候变化。哺乳动物灭绝风险的生物学与环境关联因子，呈现出鲜明的统计分布与地理分布格局。
本研究结果为理解灭绝风险地理差异背后的物种水平格局与过程提供了新视角，同时也为未来的保护研究提供了参考方向——无论是聚焦特定地理区域的保护研究，还是评估物种水平格局在多大程度上反映了物种分布范围内种群所面临压力的空间异质性。气候变化带来的额外影响，可能会提升受威胁物种的灭绝易感性，并在全球范围内扩大哺乳动物的高脆弱性区域范围。