Molecular Phylogeography Of The Phrynocephalus Forsythii

Phrynocephalus forsythii belong to the genus Phrynocephalus in the family Agamida,which mainly distributed in Tarim Basin with a broad altitudinal range from872 m to 3100 m.The habitat types of P.forsythii are mainly fixed in the desert,semi-fixed shrub or gobi desert.P.forsythii is the first species to form in the genus viviparity group.The study of its evolutionary history is helpful for us to deepen our understanding of the evolution of viviparity group.There are few studies about the phylogeographic structure of P.forsythii.but the results existed contentions: one was that P.forsythii originated in Yanqi basin and the other was that it originated in Qinghai-Tibet Plateau.In addition,global climate change has become one of the important factors threatening the survival of Phrynocephalus.Therefore,the conservation work of P.forsythii deserves people’s attention.To sum up,it is necessary to conduct a more comprehensive study for molecular phylogeography of P.forsythii and explore the influence of environment on its evolutionary history,so as to provide a scientific basis for the conservation work of P.forsythii.In this paper,mitochondrial gene(cyt-b,ND2 and ND4)sequence and nuclear gene(SNP)were used as molecular markers to solve the following problems:(1)the geographical structure and divergent time of P.forsythii;(2)the relationship between the genetic diversity and the environment of the geographical populations in the southern xinjiang desert;(3)the influence of the environmental change of the alternating cold and warm climate of the Quaternary glacial interglacial period on the evolutionary history of P.forsythii.The research results of this paper are following:(1)All the geographical populations of P.forsythii were divided into three branches: the Minfeng Group was the first to differentiate,the remaining populations along the basin were divided into the Southern Group and the Northern Group,and in both branches,the populations distributed in the westernmost part of the Tarim Basinwere the first to differentiate.The differentiation time of the minfeng branch was5.38 Ma,which was consistent with the time when the desert first appeared in the Tarim Basin.The differentiation time of the Southern Group and the Northern Group was 4.15 Ma,when the emergence of rivers and shrubs in the basin promoted the diffusion and evolution of P.forsythii.(2)Genetic diversity of P.forysthii is relatively low,which may be caused by the pressure of natural selection.In other words,the habit of P.forysthii current environment may not be conducive to its survival.(3)The results of neutral test and mismatch distribution showed that the population had not experienced rapid expansion in history,which may be related to the environment.The survival rate of P.forysthii was low due to the inappropriate environment,and the population size was difficult to increase.And the results of BSP indicated that the population size of the Mingfeng Group appeared to growth started approximately 0.1Ma,corresponding to the interglacial period of Guxiang/Baiyu glacial stage,possibly because the climate was warm and humid in the interglacial period and the habitat was suitable.On the contrary,the population size of both the Southern Group and the Northern Group experienced a fluctuation at 0.24 Ma,corresponding to the last glacial maximum.In the course of P.forysthii evolution,environmental changes always play an important role.Firstly,the formation of the phylogeographical structure is mainly due to the environmental changes in the basin,and the gradual emergence of suitable habitat environment enables the population to spread.The low level of genetic diversity indicates that P.forysthii are in an unfavorable living environment.Combined with the historical dynamics of the population,it can be speculated that the relatively dry environment is not suitable for the survival of P.forysthii.