Phylogeographic pattern and Pleistocene range reconstruction in the long-tailed hamster Cricetulus longicaudatus (Rodentia, Cricetidae) support its Tibetan origin

The "out of Tibet" hypothesis that suggests an important role of Tibetan highlands in the evolution of Central Asian cold-adapted fauna is a matter of debate. The long-tailed hamster Cricetulus longicaudatus is an important member of both steppe/semidesert Mongolian and high altitude Tibetan faunas. In this study, we analyze the mitochondrial variation in C. longicaudatus throughout a major part of its distribution range, perform molecular dating of the main divergence events, and model its historical range. The data reveal six genetic lineages, which are estimated to have diverged 100–200 kya. Four of the lineages are distributed in the northeastern part of the Qinghai-Tibetan Plateau. The northern part of the distribution range (Mongolia and southern Siberia) is almost entirely populated by another single lineage; its sister haplogroup is restricted to a small isolate in the Xingan Mountains. Species distribution modeling shows that the southern (Chinese) part of the geographic range of C. longicaudatus was relatively stable over the last 200 kya, while the northern (Mongolian) part demonstrated a high level of temporal variation, contracting considerably during cold glacials. The results suggest that the main center of origin of the long-tailed hamster was located in Tibet and that the northern part of the recent range was colonized through a single dispersal event at the Middle–Late Pleistocene boundary. At the same time, the comparative analysis of the fauna of Tibet and Mongolia indicates that the "out of Tibet" model is not the predominant pattern of geographic range evolution for small mammals.