长江中上游4个鲢群体遗传多样性分析

Analysis of the genetic diversity for 4 Hypophthalmichthys molitrix populations from middle and upper Yangtze River

鲢(Hypophthalmichthys molitrix)是我国重要的淡水经济鱼类,长江是其重要的种质资源库。为了研究长江中上游鲢群体遗传多样性现状,比较中上游群体的遗传分化,本研究采用线粒体DNA(mtDNA)细胞色素b基因(Cyt b)和控制区(D-loop)序列分析了长江中上游鲢群体遗传多样性及遗传分化状况,为鲢资源的保护和开发提供科学依据。采集了长江中上游江津(JJ)、宜昌(YC)、嘉鱼(JY)、黄冈(HG)等4个鲢群体共151尾样本。结果表明:135条Cyt b序列共检测出53个多态位点和19种单倍型,150条D-loop序列共检测出94个多态位点和48种单倍型,平均单倍型多样性指数(Hd)和核苷酸多样性指数(Pi)分别为0.693、0.00748和0.902、0.01557,2个标记数据均显示上游群体遗传多样性较中游群体高;群体间的分化指数(FST)和基因流(Nm)均表明长江上游(JJ)和中游(YC、JY、HG)地理群体间存在显著遗传分化。基于单倍型构建的NJ系统发育树及单倍型中值连接网络分析图显示,长江中上游鲢群体可划分为两个谱系,其中一个谱系主要源自上游群体。

Hypophthalmichthys molitrix is an economically important freshwater fish in China,and Yangtze River is its important germplasm library.In order to study the genetic diversity and genetic differentiation and to slove the issues of the prdection and development of H.molitrix popularions from middle and upper Yangtze River,Cyt b gene and D-loop sequences of mitochondrial DNA of H.molitrix from 4 populations(Jiangjin JJ,Yichang YC,Jiayu JY,Huanggang HG)in the middle and upper Yangtze River were used to investigate the genetic diversity and structure.The results showed that 53 polymorphic sites and 19 different haplotypes were identified among 135 Cyt b sequences,94 polymorphic sites and 48 different haplotypes were identified among 150 D-loop sequences,respectively.The average haplotype diversity(Hd)and average nucleotide diversity(Pi)of Cyt b and D-loop were 0.693,0.007 48 and 0.902,0.015 57,respectively.The data of Cyt b gene and D-loop sequences all showed that the genetic diversity of population in the upper Yangtze River was higher than that of in the middle Yangtze River.The F ST and Nm also revealed significant genetic differentiation existing between populations from middle(YC,JY,HG)and upper(JJ)Yangtze River.Both NJ(Neighbour-Joining)phylogenetic trees and network based on haplotype indicated that populations of H.molitrix could be divided into two clusters,and most of individuals in clusterⅡbelong to population JJ.