Abstract:

The Tamarisk Gerbil (Meriones tamariscinus), widely distributed in Central Asia desert, also is found in arid western Mongolia-Xinjiang region of China. In the present study, we combined the mitochondrial Cyt b gene (1 140 bp) and D-loop control regions (429 bp), a total of 1 569 bp, as molecular markers. Based on mtDNA sequence analyses, we calculated the nucleotide diversity, haplotype diversity and phylogeographic structure of the local populations, then discussed the geographical differentiation of the species. We detected 142 variable sites (9.05% of the total sequence) from 45 samples, including 34 single-state sites and 108 parsimony informative sites. No base insertions or deletions were detected.A total of 33 haplotypes were defined. Haplotype-based phylogenetic tree and haplotype network showed the 45 tamarisk gerbils clustered into two branches, of which the Ili Basin branch was the more primitive one. The divergence time for these two branches was 0.24 Ma years ago, about in the Lushan glaciation. The population had a rapid recession in the past 15 000 years, probably a result of the Last Glacial Maximum. Based on the phylogeographic patterns inferred from the genetic variation in mtDNA Cyt b gene and D-loop region, we suggest that the population in the Ili Basin should belong in M. t. jaxartensis, and those in Jungar Basin, Gansu,and Inner Mongolia should be regarded as M. t. satchouensis.

Key words: Cyt b gene, D-loop region, Genetic variation, Geographic subspecies, Tamarisk Gerbil (Meriones tamariscinus)

摘要： 柽柳沙鼠广泛分布于中亚荒漠地区,在我国分布于蒙新干旱区西部。本研究采用线粒体Cyt b 基因和D-loop控制区两个片段共1 569 bp作为分子标记,对我国蒙新区西部45 个柽柳沙鼠的核苷酸多样性、单倍型多样性及系统发生进行分析,并探讨其亚种分化。45 个柽柳沙鼠线粒体DNA 共定义33 个单倍型,包含142 个核苷酸变异位点(占全序列的9.05% ),其中单态位点34 个,简约信息位点108 个,未发现碱基插入或缺失的现象。基于单倍型的系统发生树和网络关系图显示,柽柳沙鼠的谱系分为两大支:伊犁盆地的种群聚为独立的一支,准噶尔盆地和额济纳地区的种群聚为一支,两大支的分歧时间为0.24 Ma年前,大约在庐山冰期。通过Beast 模拟,柽柳沙鼠在近15 000年有一次快速的种群衰退,表明柽柳沙鼠种群受到了末次盛冰期的影响。基于Cyt b 基和D-loop 序列的证据,我们认为分布于新疆伊犁盆地的柽柳沙鼠为哈萨克亚种(M. t. jaxartensis),分布于我国新疆准噶尔盆地以及甘肃、内蒙地区的为敦煌亚种(M. t. satchouensis)。

关键词: 柽柳沙鼠, Cyt b 基因, D-loop 控制区, 遗传分化, 地理亚种