Quaternary climate changes explain diversity among reptiles and amphibians

It is widely believed that contemporary climate determines large-scale patterns of species richness. An alternative view proposes that species richness reflects biotic responses to historic climate changes. These competing contemporary climate vs historic climate hypotheses have been vigorously debated without reaching consensus. Here, we test the proposition that European species richness of reptiles and amphibians is driven by climate changes in the Quaternary. We find that climate stability between the Last Glacial Maximum (LGM) and the present day is a better predictor of species richness than contemporary climate; and that the 0 degrees C isotherm of the LGM delimits the distributions of narrow-ranging species, whereas the current 0 degrees C isotherm limits the distributions of wide-ranging species. Our analyses contradict previous studies of large-scale species richness patterns and support the view that historic climate can contribute to current species richness independently of and at least as much as contemporary climate.