基于线粒体控制区的序列变异分析青海东部甘肃鼢鼠遗传多样性

甘肃鼢鼠(Myospalax cansus)是一种终年营地下独居生活的小型掘土类动物。本文通过测定mt DNA的控制区部分序列(530 bp)变异,分析青海东部地区8个甘肃鼢鼠地理种群遗传多样性与遗传结构。158个样本共发现26个变异位点,定义了39种单倍型,整体的平均单倍型多样性高(h=0.953 2)、核苷酸多样性低(π=0.006 36)。歧点分布和中性检验均说明青海东部甘肃鼢鼠种群在历史上存在着快速扩张的事件。基于邻接法构建的网络关系图中,单倍型呈星状分布,没有按地理位置形成对应类群。基因流(Nm)数据显示多数地理种群间基因交流贫乏,AMOVA结果显示种群内与种群间遗传变异分别为48.82%和51.18%,遗传分化明显。IBD分析表明,甘肃鼢鼠的遗传分化与地理距离呈正相关,说明距离隔离对甘肃鼢鼠种群分化具有重要作用。甘肃鼢鼠的这种遗传多样性与种群遗传结构特点,可能是地下生活方式靠挖掘迁移带来的较小扩散能力的结果。

Genetic Diversity and Population Structure of Gansu Zokors (Myospalax cansus) in Eastern Qinghai Inferred from Mitochondrial D-loop Sequences

Gansu zokors (Myospalax cansus) are small, solitary, subterranean rodents that inhabit the Loess Plateau in China. The genetic diversity and population genetic structure of M. cansus were determined by analyzing the sequence variation of a 530 bp fragment of the mitochondrial D-loop region in 158 natural individuals from eight locations in eastern Qinghai. Overall, 26 polymorphic sites were identified and 39 haplotypes were defined. Genetic diversity estimates revealed extensive haplotype diversity (0.9532) and limited nucleotide diversities (0.00636) in all populations. Analysis of neutral evolution and mismatch distribution implied that M. cansus might have experienced a recent population expansion. The median-joining network was star-like throughout the studied range of M. cansus and showed that most individuals from different populations were highly interconnected with each other and did not exhibit reciprocal monophyly. Population differentiation among populations was confirmed by the percentage of variation among populations and within populations, which were 51.18% and 48.82%, respectively. Nm analyses indicated that the gene flow was limited among sampled populations. A Mantel test revealed significant positive correlation between genetic distances, expressed by FST, and geographical distances among populations, excluding the PA1 population, suggesting that distance isolation plays a remarkable role in genetic differentiation. In the present study, the available data suggested that the Quaternary climatic oscillation and the weak dispersal ability of subterranean animals have shaped the peculiar population genetic diversity and genetic structure of Gansu zokors.