Genetic Structure And Population History Of The Reeves's Butterfly Lizard (Leiolepis Reevesii)

The Reevese's butterfly lizard Leiolepis reevesii has a most northerly distribution of the genus Leiolepis(Agamidae),ranging from South China(Guangxi,Guangdong and Hainan)to Vietnam.This lizard is among ground-dwelling tropical agamids that are undergoing population decline,for multiple reasons including habitat loss,illegal trade and human predation,and has been listed as a highly vulnerable species according to the China Red Data Book of Endangered Animals.We characterized 25 polymorphic microsatellite loci isolated from L.reevesii genomic libraries.These markers revealed a relatively high degree of genetic diversity(2-18 alleles per locus)and heterozygosity(HO ranged from 0.000-0.938,and HE ranged from 0.160-0.954).Nine microsatellite loci and mitochondrial ND4 gene were used to study genetic diversity,gene flow,population structure,evolutionary history and migration pattern of L.reevesii,and lizards were collected from 31 sample sites in China and Vietnam(covering the entire range of this animal).Our phylogenetic analysis revealed two mitochondrial lineages,Clade A and Clade B,which were estimated to have divergenced about 0.6 million years ago(Ma).Clade B contained individuals from the southern part of Hainan,others belonged to Clade A.Clade A could be further divided into three clusters according to microsatellite data,thus resulting in four clusters(Group 1,Group 2,Group 3 and Group 4)in this lizard.Group 1 contained the individals from Vietnam and Guangxi,Group 2 included the ones from Guangdong and west part of Hainan,Group 3 contained lizards from east part of Hainan,while Group 4 contained the individuals from south part of Hainan.Neutrality test,mismatch distribution analyses based on mitochondrial gene all revealed that population expansion in Group 2,and the estimated expansion time was about 0.217 Ma.The estimated times falled wihin a period of the land-bridge,Qiongzhou Strait,formation and disappearance in the Pleistocene,and related to the rise of the Tibet-Qinghai Plateau and Wuzhishan Moutain.Gene flow analysis revealed that the effective number of migrants per generation into clusters of Group 2 and Group 3 were high,and there was no significant evidences showed the lizrd was sex-biased dispersal.The Wuzhishan and Yinggeling mountain ranges were the barriers limiting gene flow between populations,whereas the Gulf of Tonkin and the Qiongzhou Strait were not.In conclusion,the phylogeographical and migration patterns of L.reevesii were the combined result of Pleistocene sea-level oscillations caused by the global climate and geographical barriers to gene flow.