Intrinsic and extrinsic drivers of change in species climatic niches

Species extinction is the most alarming consequence of global biodiversity decline, with potential dramatic effects on our economy and well-being. The current rate of global climate change, with no precedent in recent millennia, is expected to further increase the already unsustainable extinction rates; hence, there is urgent need to anticipate species loss, with conservation strategies that build on the ecological adaptation potential of species. The breadth of a species’ niche - the set of environmental conditions in which the species can persist - is the key ecological trait that allows adaptation to environmental change. Yet, while the dominant roles of direct threats and climate change as drivers of species extinction are well established, their role as drivers of niche erosion has proven difficult to quantify. This is a critical conservation gap: niche erosion plays a key role in determining species risk to changing environments but is often ignored in large-scale extinction risk assessments. We disentangle the impacts of intrinsic and extrinsic drivers of climatic niche change in terrestrial mammals, comparing the prehistoric and current realised climatic niche of >500 species. We evaluate the role of life-history, climatic, and anthropogenic drivers of climatic niche change. Separating intrinsic and extrinsic drivers of niche change is essential to understand which species are unlikely to adapt to future climates, and which conservation action is more appropriate.