The impact of climate change on large mammal distribution and extinction: Evidence from the last glacial/interglacial transition

The last major global revolution of climate was the transition from the last glacial stage to the present interglacial, ca. 25–10 ka. Vegetational belts and mammalian communities underwent major reorganisation. New radiocarbon data show that the complex series of climatic changes affected the ranges of mammalian species dramatically, but in differing ways related to the ecologies of individual species. For species that ultimately went extinct, the reduction in range was a prolonged and geographically complex process taking thousands or tens of thousands of years. Recent genetic studies using ancient DNA show that this process was often accompanied by loss of genetic variation and, presumably, adaptive flexibility. Even so, some species survived for thousands of years in small, terminal refugia before finally becoming extinct – a pattern akin to the ‘extinction lag’ or ‘extinction debt’ posited for endangered modern taxa. Whether refugial species can survive to re-expand into new areas, especially in anthropogenically disturbed environments, is determined by a complex of factors and is not inevitable.