干旱区生态环境知识资源中心

Changes in the palaeoenvironment and paleoclimate expedite the process of evolutionary divergence in animals. The evolutionary events of some small mammals distributed in Xinjiang Arid Region remain ambiguous. Thus, it is necessary to predict their evolutionary histories based on divergence estimates. Some museum specimens were involved in this analysis because of sampling limitation for threatened species in the arid region. A related problem is that some mutilated specimens without complete taxonomic data made it difficult to directly analyze species divergence. Here, sequences of cytochrome c oxydase I were used to identify museum specimens and combined with cytochrome b to estimate the recent divergence of extant small mammals constrained with eight fossil calibrations. The results showed that the massive species differentiation emerged during the Middle and Late Miocene periods. We inferred that differentiation of these small mammals might be associated with the retreat of the Tethys Sea from the Tarim Basin around the Eocene-Oligocene boundary and the global climate fluctuations during the Miocene period. Furthermore, the aridification and changes in the Taklimakan and Gurbantunggut Deserts might have driven the diversification of intraspecies and the emergence of cryptic species since the Late Pleistocene.