基于12SrRNA和ND3基因序列分析巨[鱼丕]遗传多样性及系统进化

为从分子水平研究巨鱼丕](Bagarius yarrelli Sykes)的遗传多样性和系统进化关系,本实验对采集于怒江、澜沧江、元江3河流5种群中的60个个体进行12S rRNA和ND3基因序列的PCR扩增,同时与红河河口群体12个个体的12S rRNA和ND3基因序列进行比对分析,采用Mega5.02软件对碱基组成、Kimura-2 parameter遗传距离、可变位点等进行分析。应用DnaSP软件进行遗传多样性相关参数的计算。结果显示:12S rRNA和ND3基因序列长度分别为954 bp和346 bp(349 bp),分别定义了51个单倍型和42个单倍型,12S rRNA和ND3序列中的碱基平均含量分别为:T为20.8%、C为25.7%、A为32.1%、G为21.4%和T为29.5%、C为28.2%、A为28.1%、G为14.1%,表现出明显的A+T偏倚性;6个群体的群体内和群体间的遗传距离分别为0.003~0.284(12S rRNA),0.009~0.059(ND3)和0.004~1.062(12S rRNA),0.008~0.143(ND3);12S rRNA基因的51个单倍型和ND3基因的42个单倍型序列总的单倍型多样性(Hd)、核苷酸多样性(Pi)及核苷酸平均差异数(K)分别为0.972和0.937、0.035和0.079、31.414和27.176,均显示出丰富的遗传多样性。结合从GenBank中下载的12S rRNA和ND3基因同源序列的鱼丕]科9属10种鱼类进行系统发育树的构建,结果表明巨鱼丕]独自汇聚成一大单系群,怒江潞江坝群体、怒江三江口群体及澜沧江临沧群体间关系较近,澜沧江景洪群体可单独构成一个单系种群,红河河口群体、红河曼耗群体与其它巨鱼丕]构成一单系种群后再同澜沧江景洪群体汇聚成一支。

Genetic diversity and phylogenetic analysis of Bagarius yarrelli based on 12S rRNA and ND3 gene sequences

In this study,the genetic diversity and phylogenetic relationship of five Bagarius yarrelli populations(12 individuals for each population)in Nujiang River,Lancing River and Yuanjiang River were analyzed based on the 12S rRNA and ND3 gene sequences,meanwhile,the 12S rRNA and ND3 gene sequences of the five B.yarrelli populations were compared with that of the B.yarrelli population collected in the estuary of Honghe Rivers.The base composition,kimura-2 parameter genetic distance and variable loci were analyzed by Mega5.02 software.DnaSP software was used to calculate the related parameters of genetic diversity.Results show that the full length of the 12SrRNA and ND3 gene sequences was 954 bp and 346 bp(349bp),consisting of 51 haplotypes and 42 haplotypes,respectively.The average base content of the 12S rRNA sequences was 20.8%for T,25.7%for C,32.1%for A,21.4%for G and,in terms of the ND3 sequences,the average T,C,A,G content was 29.5%,28.2%,28.1%and 14.1%,respectively,showing significant A+T bias.The genetic distances within and between the six B.yarrelli populations were in the range of 0.003~0.284(12S rRNA),0.009~0.059(ND3)and 0.004~1.062(12S rRNA),0.008~0.143(ND3),respectively.The total haplotype diversity(Hd),nucleotide diversity(Pi)and the average nucleotide mean difference(K)of the 51 haplotypes of 12S rRNA gene and the 42 haplotypes of ND3 gene were 0.972,0.035,31.414 and 0.937,0.079,27.176,respectively,indicating high genetic diversity among populations.Based on the 12S rRNA and ND3 homologous sequences of 10 Sisoridae species from 9 genera downloaded from GenBank,the phylogenetic trees of Bagarius yarrelli populations was constructed using neighbor-joining(NJ)method and the results show that B.yarrelli clustered into a single clade,and the relationship among Nujiang-Lujiangba population,Nujiang-sanjiangkou population and Lancangjiang-Lincang population was relatively close.Lancangjiang-Jinghong population formed a monophyletic population,and Honghe-Hekou population and Honghe-manhao population constituted a monophyletic group with other B.yarrelli population and then clustered into a clade with Lancangjiang-Jinghong population.