Phylogeography of the Japanese ratsnake, Elaphe climacophora (Serpentes: Colubridae): Impacts of Pleistocene climatic oscillations and sea-level fluctuations on geographical range

Abstract

In coastal and insular regions, both climatic and sea-level changes during the Pleistocene had great influence on the population sizes and/or ranges of terrestrial animals. We investigated the intraspecific phylogeography of the Japanese ratsnake (Elaphe climacophora) to examine the differences in demographic patterns between regions with different degrees of impact during glacial periods on the Japanese Archipelago. We show that the population size of E. climacophora decreased greatly in northern Japan during glacial periods, and that it survived at least the last glacial period even in the northernmost area of Japan, Hokkaido. In south-western Japan, in contrast, the range of E. climacophora expanded during the early stage of the last glacial period when additional terrestrial habitats emerged because of sea-level fall. Subsequently, however, the population size contracted in south-western Japan because of climate cooling until the last glacial maximum. Thus, the historical demography of E. climaciphora differed considerably between northern and south-western Japan. The demographic pattern was also different even in the same region, south-western Japan, depending on the degree of global cooling during the last glacial period.