长江流域种群遗传多样性和遗传结构分析

摘要

Fish population genetics have mainly focused on economic fish or endangered species, while the knowledge on genetic structure of the fish with low economic value is limited. In the present study, we collected a total of 323 sharpbelly (Hemiculter leucisculus) individuals from 13 populations in Yangtze River Basin and the affiliated lakes to evaluate their genetic diversity and population structure by amplifying the mitochondrial DNA Cyt b gene fragments (1100 bp). Genetic diversity analysis showed the pattern of high haplotype diversity and high nucleotide diversity, sug-gesting that the populations in the Yangtze River Basin were fairly stable. In addition, based on mitochondrial cyto-chrome b gene phylogenetic analysis, there were five mitochondrial lineages (lineage A-F). The neutral test of Fu’Fs and mismatch distributions with negative Tajima’s D values indicated that the lineage A, B, E, and F underwent population expansion, and the expansion was from the upper section to the middle section of the Yangtze drainage. Fst and phy-logenetic analysis and the significant divergence among lineages A-F implied that there are at least four different species on the level of mitochondrial DNA in the Yangtze River Basin. The population genetic structure and diversity of Hemiculter leucisculus may reflect the distribution pattern in Yangtze River Basin.%鱼类群体遗传学研究主要集中在经济鱼类或濒危物种，然而一些经济价值较低的物种的遗传结构却甚少关注。因此，研究选择了经济价值较低的(Hemiculter leucisculus)，共计323尾个体分别来自13个长江流域及其附属湖泊的自然群体。通过扩增线粒体DNA Cytb基因序列片段(1100 bp)，以探讨种群遗传结构和遗传多样性。遗传多样性分析呈现出高单倍型多样性和高核苷酸多样性的模式，表明该种群在长江流域较为稳定。另外，基于线粒体细胞色素 b 基因的系统发育分析，显示有5个线粒体谱系(谱系 A-F)组成。中性检验和核苷酸错配分布分析均显示谱系A、B、E、F曾经历过种群扩张，并且呈现从上游向中游扩张的规律。谱系间较高且显著的遗传分化指数和显著的系统进化关系，均表明谱系 A-F 之间存在明显的遗传分化，暗示长江流域可能至少存在4个不同线粒体DNA水平上的种。种群的遗传结构和多样性可能受到了长江流域特定格局的影响。