The divergence of small mammals in Xinjiang, China, as revealed by phylogentic analyses of COI and Cytb

Abstract

Cbanges in tbe palaeoenvironment and paleoclimate expedite tbe process of evolutionary divergence in animals. Tbe evolutionary events of some small mammals distributed in Xinjiang Arid Region remain ambiguous. Tbus, it is necessary to predict tbeir evolutionary bistories based on divergence estimates. Some museum specimens were involved in tbis analysis because of sampling bmitation for tbreatened species in tbe arid region. A related problem is tbat some mutilated specimens witbout complete taxonomic data made it difficult to directly analyze species divergence. Here, sequences of cytocbrome c oxydase I were used to identify museum specimens and combined witb cytocbrome b to estimate tbe recent divergence of extant small mammals constrained witb eigbt fossil calibrations. Tbe results sbowed tbat tbe massive species differentiation emerged during tbe Middle and Late Miocene periods. We inferred tbat differentiation of tbese small mammals migbt be associated witb tbe retreat of tbe Tetbys Sea from tbe Tarim Basin around tbe Eocene-Oligocene boundary and tbe global climate fluctuations during tbe Miocene period. Furtbermore, tbe aridification and cbanges in tbe Taklimakan and Gurbantunggut Deserts migbt bave driven tbe diversification of intraspecies and tbe emergence of cryptic species since tbe Late Pleistocene.