Chen Weicai, Liu Shaoying, Liu Yang, Hao Haibang, Zeng Bo, Chen Shunde, Peng Hongyuan, Yue Bisong, Zhang Xiuyue
Sichuan Key Laboratory of Conservation Biology on Endangered Wildlife, College of Life Sciences, Sichuan University, Chengdu, Sichuan 610064, China.
Zoolog Sci. 2010 Jun;27(6):487-93. doi: 10.2108/zsj.27.487.
The Hengduan Mountains, situated in the southeastern Tibetan Plateau, have undergone dramatic geological and climatic changes over the Pleistocene epoch. Several studies have revealed that the mountains served as a refugium during the ice age. The large white-bellied rat Niviventer excelsior is a rodent endemic to the Hengduan Mountains, which makes it an appropriate species for investigating the influence of glacial movements on the genetic structure of mammals. In this study, we sequenced the partial mitochondrial DNA control region from 72 N. excelsior specimens collected from 20 localities. The results revealed very high levels of haplotype diversity (h = 0.947) and nucleotide diversity (pi = 0.101) in this species. No common haplotype was found to be shared in samples from all geographic regions. Demographic analyses suggested that N. excelsior populations had not been subject to either expansion or bottleneck. The phylogenetic relationships among the haplotypes have no correlation with their geographical origins, while topology revealed two major clades. We speculate that the populations of N. excelsior may have been restricted to two separate refugia during the Last Glacial Maximum (0.60-0.17 Mya), with one west and one east of the Shaluli Mountains. Between the two major refugia, there existed a more widely distributed network subrefugia, which conserved genetic variations in N. excelsior. These results indicated that complex topographic configuration in the Hengduan Mountains provided a network of refugia to maintain the high level of genetic diversity in Pleistocene glaciations.
横断山脉位于青藏高原东南部，在更新世经历了剧烈的地质和气候变化。多项研究表明，这些山脉在冰河时代曾是避难所。大耳姬鼠是横断山脉特有的啮齿动物，这使其成为研究冰川运动对哺乳动物遗传结构影响的合适物种。在本研究中，我们对从20个地点采集的72个大耳姬鼠样本的部分线粒体DNA控制区进行了测序。结果显示，该物种的单倍型多样性（h = 0.947）和核苷酸多样性（pi = 0.101）非常高。在所有地理区域的样本中未发现共享的常见单倍型。种群动态分析表明，大耳姬鼠种群没有经历过扩张或瓶颈效应。单倍型之间的系统发育关系与其地理起源无关，而拓扑结构显示出两个主要分支。我们推测，在末次盛冰期（0.60 - 0.17百万年前），大耳姬鼠种群可能被限制在两个独立的避难所，一个在沙鲁里山以西，一个在沙鲁里山以东。在这两个主要避难所之间，存在一个分布更广泛的网络亚避难所，它保存了大耳姬鼠的遗传变异。这些结果表明，横断山脉复杂的地形结构提供了一个避难所网络，以维持更新世冰川作用期间的高遗传多样性水平。
