三个地理种群的董氏须鳅遗传多样性及种群历史动态

研究采用线粒体DNA Cyt b和D-loop基因分析西辽河、松花江和穆棱河3条水系董氏须鳅(Barbatula toni)的遗传多样性和种群结构, 并探讨其种群演变历史。结果表明: 3条水系119个董氏须鳅样本共检测出57个单倍型, 各群体间不存在共享单倍型; 3个董氏须鳅地理群体均呈现出较高的单倍型多样性(0.805—0.926)和较低的核苷酸多样性(0.00095—0.00458); AMOVA分子方差分析、群体间分化指数(F_ST)、系统发育树及单倍型网络图均表明3个地理种群已经出现高度分化, 群体间遗传变异占总变异的79.45%, 遗传分化显著(P<0.01)。中性检验和错配分析表明, 松花江和穆棱河群体历史上发生了群体快速扩张。参考鳅科鱼类Cyt b基因0.68—0.84%/Ma的进化速率, 估算3个地理群体的分歧时间为1.082—0.669 Ma前, 松花江和穆棱河群体扩张时间为0.071—0.047 Ma前, 推测我国董氏须鳅在中更新世期随冰期迁移至不同避难所, 形成各地理群体, 并于晚更新世早期经历了群体扩张事件。

GENETIC DIVERSITY AND POPULATION DEMOGRAPHIC HISTORY OF THREE POPULATIONS OF BARBATULA TONI (CYPRINIFORMES,NEMACHEILINAE) FROM NORTH CHINA

Natural resources of Barbatula toni have been seriously damaged in recent years due to habitat destruction and overfishing, which need urgent protection. The present study used mitochondrial DNA Cyt b and D-loop genes as molecular maker to perform the genetic diversity and phylogeographic analyses of three populations of B. toni from north China. 57 haplotypes were identified for 119 individuals of B. toni. No haplotype shared among different populations. Relatively high haplotype diversity (h=0.805—0.926) and low nucleotide diversity (π=0.00095—0.00458) were detected in three populations of B. toni. Haplotype Bayesian tree showed that B. toni from three river systems were separa-tely clustered as three clades. Analysis of molecular variance (AMOVA) indicated that the variation among populations (accounting for 79.45%) was the main source of variation. Differentiation index (F_ST) of three populations showed significant difference with F_ST >0.25 (P<0.01). Neutrality tests and mismatch distribution indicated the recent demographic expansion of B. toni. According to the average evolution rate of Cyt b of Cobitis melanoleuca from Siberia (0.68—0.84%/Ma), the divergence time of three populations of B. toni was 1.082—0.669 Ma, and recent demographic expansions time was at 0.071—0.047 Ma. Pleistocene climatic changes could be a key factor of the population dyna-mics.