间颅鼠兔的种群遗传结构和历史演化动态

Population genetic structure and demographic history of Ochotona cansus( Lagomorpha,Ochotonidae)

本研究基于多个线粒体基因(包括COI、Cyt b、tRNA-Thr、tRNA-Pro、D-loop控制区部分序列共计2417 bp)对间颅鼠兔(Ochotona cansus)的种群遗传结构和历史演化动态进行了研究。基于线粒体基因联合数据构建的贝叶斯树显示,间颅鼠兔分为两大支系:来自岷山山系东部的甘肃白水江和四川唐家河的种群组成了支系一;其余采样点的种群组成了支系二。基于以上基因所构建的单倍型网络图显示的遗传结构与贝叶斯树一致。贝叶斯聚类分析(BAPS)将间颅鼠兔分为4个地理种群。A种群包括甘肃白水江(BSJ)和四川唐家河(TJH)的样本;B种群仅包括四川卧龙(WL)的样本;C种群包括青海北部种群(GC、MY、QL)、青海南部—四川北部种群(JW、JZ、ZK、RE)、四川康定(KD)和陕西太白山(TB)的样本;D种群包括山西娄烦(LF)以及陕西吴起(WQ)的样本。基于线粒体基因构建的物种树进行支系分化时间的推测,结果显示4个地理种群的分化时间分别约为0.72 Ma、0.32 Ma、0.12 Ma,这与造成青藏高原剧烈隆起的昆黄运动(1.10-0.60 Ma)和共和运动(0.15 Ma)发生时间基本吻合。采用中性检验、错配分布、扩展贝叶斯天际线(EBSPs)3种方法对间颅鼠兔的种群历史动态进行预测,分析结果显示间颅鼠兔在历史上并没有经历过显著的种群扩张,而且在末次盛冰期后开始衰减。生态位模型(ENM)预测结果表明:末次盛冰期时间颅鼠兔的潜在分布区比其现今分布区小,末次盛冰期比末次间冰期潜在分布区略大,表明间颅鼠兔受末次盛冰期影响较大。气候因子分析显示降水比温度对间颅鼠兔种群影响更大,推测降水对植被的演化影响显著,从而影响间颅鼠兔的食物来源和栖息环境。

In the present study, we studied the population genetic structure and demographic history of Gansu pika （O. cansus） by using multiple mitochondrial loci （COI, Cyt b, tRNA-Thr, tRNA-Pro, and a control region, totaling 2417 base pairs）. Bayesian analysis of the concatenated genes revealed two major lineages： Lineage 1 included samples from Baishuijiang and Tangiiahe; Lineage 2 contained samples from the other 12 locations. The phylogenetie structure of haplo- type network built based on the same genes was almost the same as that of the Bayesian tree. Bayesian analysis of popula-tion structure （BAPS） divided O. cansus into four geographic populations. Population A contained samples from Baishui-jiang and Tangjiahe; B included WL （Wolong, Sichuan） only; C included North Qinghai population （GC, MY, QL）, South Qinghai-North Sichuan population （JW, JZ, RE, ZK）, KD （Kangding, Sichuan ）, TB （Taibai Mountain, Shaanxi） ; and D included LF （Loufan, Shanxi） and WQ （Wuqi, Shaanxi）. Species tree constructed on mtDNA showed that the major divergence time for the four geographic populations were： 0. 72 Ma, 0. 32Ma, 0. 12Ma, which generally co-incided with the Kunhuang Movement （ 1.10 -0. 60Ma） and Gonghe Movement （0. 15Ma）, the two dramatic geological events during the uplift of Qinghai-Tibetan Plateau. Moreover, we estimated the demographic history of O. cansus by using three methods： neutrality tests, mismatch distributions and extended Bayesian skyline plots. The results indicated that 0. cansus might have not experienced population expansion, but it was significantly decreased since the Last Glacial Maxi-mum. The Ecological Niche Modeling indicated that the potential distribution of O. cansus in the Last Glacial Maximum （LGM） is smaller than Current and LIG, and that precipitation played a more important role than did temperature in the population dynamics of Gansu pika. This is possibly because precipitation strongly influences the food resources and habi-tats of Gansu Pika by affecting the vegetation succession.