关键词: 子午沙鼠, Cyt b, 柴达木盆地, 遗传多样性, 系统进化, 环境变化

Abstract: The genetic diversities and population structures of Meriones meridianus representing 4 populations in the Qaidam Basin were investigated by examining mitochondrial Cyt b sequences. The results showed that Lenghu-Suganhu population had the highest genetic diversity (Hd =  1.000; π = 0.00530), while the Geermu population had the lowest(Hd = 0.750; π = 0.00255). AMOVA analyses indicated that 38.32% of the total genetic variation was attributable to differences among populations and 61.68% to differences among individuals within populations. A low level of genetic differentiation was found between the Lenghu-Suganhu and other populations and a high level was detected between the Geermu and other populations. Gene flow was extensive between populations except for the Geermu population. Phylogenetic analysis revealed that, as the original population in Qaidam Basin, M. meridianus in Lenghu-Suganhu spread from west to east along the basin periphery. The results of Mantel test illustrated that it was not obviously relevant between genetic distance and geographic distance among geographic populations (r = 0.031, P = 0.938). The Last Greatest Lakes Period on the Qinghai-Tibet Plateau might be the major cause for genetic differentiation among M. meridianus populations in the Qaidam Basin.

Key words: Cyt b, Environmental variation, Genetic diversity, Midday gerbil (Meriones meridianus), Phylogenetic evolution, Qaidam Basin