Physiographic and climatic events in the Chihuahuan Desert lead to the speciation and distinct demographic patterns of two sister Sceloporus lizards

The biogeographic history of the Chihuahuan Desert is known to be complex, and there is evidence of the effects of physiographic and climatic events in species diversification and demographic population changes in many taxa. Here, using DNA sequence data, we studied the influence of the physiographic and climatic events that occurred in the Chihuahuan Desert during the Pliocene–Pleistocene transition on the speciation and evolutionary history of the sister lizard species Sceloporus cyanostictus and S. gadsdeni. First, based on mtDNA and nDNA sequences, we estimated the divergence times of the sister species. Then, based on mtDNA sequences, we investigated the demographic history of both species within a phylogeographic framework. The divergence time was inferred to be 1.48 Mya, date that corresponds to the existence of a large lake in the Mapimian subprovince, between the current geographic locations of S. cyanostictus and S. gadsdeni. This lake could have acted as a barrier, leading to the speciation of both species. For the demographic history of the two species, we identified two distinct patterns: the population expansion of S. gadsdeni within the Last Glacial Maximum and the potential population decline of S. cyanostictus. Our results can be used as a guide for the study of other aspects that could be critical to developing conservation actions that ensure the survival of not only S. gadsdeni and S. cyanostictus, but also other co‐occurring lizard species.     

广东植物区系的分区

广东植物区系与广西中部、东南部及福建西南部、中部及湖南南部、江西南部的植物区系关系最为密切,它们共同组成了华南省,属东亚植物区．华夏植物界．传统的以北极起源理论或热带起源理沦为依据．将中国植物区系特别是广东亚热带植物区系,分割成泛北极植物界和古热带植物界是不符合客观实际的．亚洲热带至亚热带无论在植物区系组成上还是在森林群落的结构上都是一整体．它们是华夏起源的．华南省植物区系可达７５００种．中国特有属达８６属,地区特有属约１５属．如猪血木、四药门花、圆籽荷、辛木、虎颜花、梅兰、四数苣苔、报春苣苔、拟九节、小花苣苔、圆唇苣苔等属．华南省又可分为三个亚省：粤西南—桂东南亚省,粤东南—闽西南亚省,粤北—闽西北亚省,三个亚省在地质史上,气侯区上,植物区系组成上都有各自的特点。