华南沿海西部美丽小条鳅基于线粒体控制区的种群遗传变异及亲缘地理格局

为研究其种群遗传变异和亲缘地理格局,分析了107尾采自华南西部和海南岛的12条水系的美丽小条鳅(Micronoema-cheilus pulcher Nichols)控制区934-938 bp的序列,其中有79个核苷酸变异位点。分子变异分析(AMOVA)表明,种群间的遗传变异占46.88%,种群内的遗传变异占55.06%。基于36个单倍型的系统树显示,12条水系的种群聚成两支。其中,广西沿海诸独立水系(防城河、峒中河、北仑河、南流江)和西江水系与广东漠阳江和潭江水系关系密切,而海南岛万泉河和南渡江与广东鉴江水系关系密切。根据嵌套进化枝系地理分析(NCPA)推测,防城河周边地区可能是美丽小条鳅的扩散中心,该物种可由此区域通过两条途径扩散:(1)沿西江水系向广西沿海独立水系至广东漠阳江和潭江水系扩散;(2)向海南岛诸水系再至雷州半岛的鉴江水系扩散。在演化过程中,曾发生片断化事件、长距离建群和持续的分布区扩张。

Population genetic variations and phylogeography of Micronoemacheilus pulcher Nichols based on mtDNA control region

The population genetic variations and phylogeographical patterns of 107 Micronoemacheilus pulcher from 12 drainage systems in western South China were investigated based on 934-938 base pairs (bp) nucleotide sequences of mtDNA control region. We found 79 nucleotide sites variable in the full sequence. Analysis of molecular variance (AMOVA) revealed that genetic variation within the populations was 42.84%, among the populations was 58.53%. Thirty-six haplotypes of the mtDNA control region were analyzed using the neighbor-joining method. The populations of 12 drainage systems could be divided into two lineages. The drainages in Guangxi (Fangcheng River, Dongzhong River, Beilun River and Nanliujiang River) and Xijiang River were more closely related to Moyangjiang River and Tanjiang River, the Wanquanhe River and Nandujiang River in Hainan island were closely related to Jianjiang River in Guangdong Province. Nested clade phylogeographic analysis indicates that this fish has originated from the joining area of Guangxi and Vietnam (in which Dongzhong River, Beilun River and Fangcheng River are located) and spread to other drainages by two ways: (1) through Xijiang River spread to drainages of Guangxi, Moyangjiang River and Tanjiang River of Guangdong Province; (2) through ancient river systems between Hainan Island and Vietnam to Hainan Island, then back to the mainland expanding northward to Jianjiang River of Leizhou Peninsula in Guangdong Province. The current phylogeographical distribution of the populations might have formed by several events: allopatric fragmentation, long-distance colonization possibly coupled with subsequent allopatric fragmentation, contiguous range expansion.