Abstract
The Mongolian Plateau (MP), which is situated in the interior of Asia and possesses a typical continental climate, experienced harsh climatic conditions during the Quaternary glacial fluctuations. Although these events likely had huge impacts on the local animal populations, the current effects have hardly been explored. To investigate whether the MP supported a refugium along an oceanic-continental gradient (ROCG), and whether this refugium was glacial or interglacial, we investigated the demographic and phylogeographic history of an endemic mammal species, the desert hamster Phodopus roborovskii. We reconstructed the demographic variation, the phylogeographic diffusion, and modelled the potential habitat during historical periods. The genetic diversity in the MP was the highest among all the localities, and the MP was a suitable habitat throughout the modelled historical periods. A phylogeographic diffusion analysis emphasized the importance of the MP as the centre of origin, preservation and spread for P. roborovskii. The homogeneous landscape provided the opportunity for a wide gene flow, which resulted in low resolution of the phylogenetic relationships. Moreover, P. roborovskii was favoured by the interglacial condition, with both its demographical and geographical ranges expanded within the interglacial periods. The range variation from the Last Glacial Maximum to the current condition reflects a distinct longitudinal shift, while both ranges largely contracted from that of the Last Interglacial. Our results support that the MP served as a refugium and spread centre for P. roborovskii during the Quaternary climate fluctuations. The interglacial expansion and the longitudinal shifts highlighted the important effects of precipitations on the distribution range of species adapted to arid and semi-arid during glacial oscillations.
Highlights
The role of the Pleistocene climatic oscillations in shaping species distributions, genetic diversification and demography has been widely studied [1]
We asked the following questions: 1) did the Mongolian Plateau (MP) served as preservation centre for P. roborovskii during unfavourable periods of climate change? And if it did, 2) did the refugium served for the interglacial period or for the glacial period? 3) did the P. roborovskii shifted its habitat along the oceanic-continental (OC) axis during the climatic fluctuations? Considering the biological and ecological characteristics of continental climate-dwelling animals, we proposed the following two hypotheses: 1) the MP served as an interglacial refugium and a glacial expansion centre for P. roborovskii; and 2) P. roborovskii shifted its range along the OC axis during the climatic fluctuations
The Mongolian Plateau played an important role in the evolutionary history of P. roborovskii during the Quaternary climate fluctuations, both as origin and preservation centre
Summary
The role of the Pleistocene climatic oscillations in shaping species distributions, genetic diversification and demography has been widely studied [1]. The pattern of elevational and latitudinal range shifts during glacial cycles remains the focus of scientific debate The concept of longitudinal range shifts along an oceanic-continental gradient (ROCG) has been introduced [4]. This gradient of oceanic–continental climate was significantly variable during the Pleistocene glacial cycles. A previous study on a continent-adapted species, the European ground squirrel (Spermophilus citellus) in the south-eastern European steppe [5], showed a demographical increment due to the range expansion of the steppe environment during the glacial periods. Further comprehensive studies are required to better understand the geographical evolutionary processes that affect continentadapted taxa
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