喜马拉雅旱獭线粒体DNA控制区遗传多样性及系统发育

喜马拉雅旱獭是青藏高原的优势种,数量多、分布广,全面了解其遗传背景对该地区旱獭资源的保护与合理利用具有重要的意义。本研究以青藏高原云南、西藏和青海三省区共13个地理种群计258只旱獭为研究对象,PCR扩增获得线粒体DNA控制区基因部分序列(887 bp),并运用种群遗传学方法进行遗传多样性分析。结果显示:258份样品共发现了84个变异位点(9.40%),定义了68种单倍型,其单倍型多样性(h)平均值为0.968±0.003、核苷酸多样性(π)平均值为0.017 25±0.016 37,种群总体遗传多样性较高。AMOVA方差分析显示13个地理种群间存在着明显的遗传分化(Fst=0.620 67,P<0.001),种群间基因交流多数较低(Nm<1)。基于单倍型构建的系统发育树中13个地理种群的喜马拉雅旱獭聚为两支,其中来自青藏高原西南地区(西藏安多、青海格尔木、青海囊谦、云南迪庆)的18个单倍型聚成一个大的分支(A支),其余50个单倍型聚为一个大的分支(B支),在NETWORK网络图中也可见到相似网络拓扑结构。研究结果显示青藏高原喜马拉雅旱獭种群以唐古拉山脉为界分为两个大的种群,说明地理隔离是影响喜马拉雅旱獭种群动态变化的主要因素。

Genetic diversity and phylogenetic relationships based on mtDNA control region sequences of Marmota himalayana

The Himalayan marmot (Marmota himalayana) is an exceedingly common species widely-distributed across vast areas of the Qinghai-Tibet Plateau. In order to improve conservation and management strategies of this species, we must understand its genetic structure and genetic diversity at the population level. In this study, 258 Marmota himalayana individuals were collected from 13 geographic populations. The genetic diversity and genetic structures of these populations were analyzed according to the sequence variation of the mitochondrial D-loop sequence. All 258 samples were successfully sequenced for 887 bp of the mitochondrial D-loop sequence. We found 84 sites (22.49%) to be polymorphic and genetic diversity was high overall (mean haplotype diversity 0.968±0.003, mean nucleotide diversity 0.01725±0.01637). The results of AMOVA analysis showed obvious genetic differentiation (Fst=0.62067, P<0.001) and relatively low gene flow among different populations (Nm<1). A neighbor-joining phylogenetic tree produced two main branches; the first branch (A) included 18 haplotypes from the southwestern Qinghai-Tibet Plateau (including Tibet Andu, Qinghai Golmud, Qinghai Nangqian, and Yunnan Diqing), and the second branch (B) included the other 50 haplotypes from the northeastern Qinghai-Tibet Plateau. A similar topology was also found using network diagram methods. Populations of the Himalayan marmot on the Qinghai-Tibet Plateau are separable into two groups, with the Tanggula Mountains serving as a geographic barrier between them. Therefore, geographical isolation via this mountain range appears to be the primary factor enforcing genetic structure of Himalayan marmot populations.