关键词: 长爪沙鼠, 细胞色素b 基因, 遗传变异, 地理分化

Abstract: In order to investigate genetic structure and population history of Meriones unguiculatus,a total of 1 140 base pairs (bp)of the mitochondrial Cyt b gene were sequenced from 52 individuals of six populations in the arid regions of China. Among the sequences of 1140 bp,74 nucleotide sites were variable,including 65 transitions and 9 transversions. Significant genetic subdivision existed between Baotou population and the other populations,however not among other populations. A total of 37 haplotypes were detected and phylogenetic analyses recovered two distinct clades (Clade A and Clade B). Clade B consisted of tree haplotypes from the Eastern Helan Mountains population,the other haplotypes were in Clade A. A unimodal mismatch distribution of the Clade A was observed,and the Tajima's D test and Fu test were all significantly negative (D = - 1.86, P <0.05 and Fs = - 21.89, P<0.05), and suggests that a population colonization and expansion of M. unguiculatus occurred. The expansion times were estimated as 0.011 million years ago at the last interglaciation stage. The climatic oscillation during the Quaternary ice ages might resulted in the intra-specific divergences (Clades A and B)and the Eastern Helan Mountains might have served as a glacial refugium and harbored both distinct lineages. The present distribution of this species was probably shaped through the rapid range expansion from the refugium during the last interglaciation stage.

Key words: Clawed jird (Meriones unguiculatus), Cytochrome b (Cyt b), Genetic structure, Geographicial variation