Phylogeography And Taxonomy Study Of Rhadbophis Nuchalis Species Group In China

This is the firstly systematically study on Rhabdophis nuchalis species group since it was described by Jiang and Zhao(1983).This species group including three species,R.nuchalis,R.pentasupralabialis and R.leonardi.Researches showed that interspecies and intraspecies diversity has been uncovered.Four questions herein:(1)Whether the differences represent intraspecies geographic differentiation from different lineages or some mysterious cryptic species and subspecies?(2)What interspecies relationship between the three species of R.nuchalis species group?(3)When did the major lineages and species diverge?(4)In what geographic area did this clade originate and how did the lineages arrive at their current distributions? We used four mitochondrial DNA fragments including cyt b?Co I?12S and16 S,and one nuclear DNA fragment c-mos,to investigate the molecular phylogenetic,phylogeographic and population analysis to resolve above questions and clarify some questions about the current species group.The main results of this study are as follows:(1)Seven clades were showed in phylogenetic analysis.It was originally divided by morphology into two species,R.nuchalis and R.leonardi,each of which has two clades.However,morphological division of the species belonging to R.pentasupralabialis exist three clades.One of these three clades from the western edge of the Sichuan Basin is not formed a monophyletic with the clade from the type locality.(2)The ancestor area reconstruction result suggested that R.nuchalis species group originated in Hengduan Mountains at approximately 6.24 Mya and migrate northward to the Qinling-Daba Mountains.The Sichuan Basin appeared as a hindrance to migration.Species divergence is closely related to the rapid uplift of Qinghai-Tibet plateau.This study speculates that the rapid uplift of the Qinghai-Tibet Plateau plays a vital role in the formation of species diversity at least in this species group.The results of population Historical demography indicate each clade in this species group has risen steadily.(3)The integrative taxonomic approach combined phylogenetics,phylogeographic,species delimitation and morphology indicated that not only three species in this species group as original description.There is a species from the western edge of the Sichuan Basin had been never described,and a subspecies of R.leonardi proved to exist.