基于线粒体COI基因的江苏湖泊鳙群体遗传多样性分析

摘要:

为了解江苏湖泊鳙群体遗传资源状况及科学开展增殖放流，采用线粒体COI基因研究了6个湖泊(太湖、滆湖、长荡湖、高邮湖、洪泽湖和骆马湖)鳙群体的遗传多样性及遗传结构。结果显示，在分析的630bp的COI基因片段中，碱基A+T含量(55.3%)大于G+C含量(44.7%)。223条COI序列检测出14个变异位点，定义9个单倍型，平均单倍型多样性和核苷酸多样性分别为0.576和0.0012，具有高单倍型多样性和核苷酸多样性的特点。6个群体的单倍型多样性为0.494~0.665，核苷酸多样性为0.0009~0.0019，表明6个湖泊鳙群体遗传多样性较低。分子方差分析结果显示，遗传变异主要来自于群体内(99.39%)，总遗传分化指数为0.0061。群体间遗传分化指数为-0.0228~0.0445，遗传距离为0.0012~0.0027，表明群体间没有明显遗传分化。单倍型邻接关系树和网络结构图显示，单倍型在6个群体中混杂分布，未形成特定的湖泊分支。中性检验和歧点分布分析表明，整个鳙群体经历过显著的种群扩张。研究表明，江苏湖泊鳙群体遗传多样性较低，遗传结构趋于同质化，需要采取措施提高鳙的遗传多样性

Abstract:

In order to understand the genetic status of Aristichthys nobilis populations from six freshwater lakes and scientifically carry out stock enhancement, the genetic diversity and genetic structure of 223 A. nobilis from Tai Lake, Ge Lake, Changdang Lake, Gaoyou Lake, Hongze Lake and Luoma Lake were analyzed in Juangsu province based on COI gene sequences. The results showed that the studied fragment length of COI gene was 630bp, and the A+T base composition(55. 3%) was higher than the C+G combination (44.7%). A total of 14 variable sites were detected and 29 haplotypes were defined from 223 COI sequences, and the average haplotype diversity index (Hd) and nucleotide diversity index (Pi) was 0. 576 and 0. 0012, respectively, revealing high haplotype diversity and low nucleotide diversity pattern. The haplotype diversity of six populations ranged from 0.494 to 0.665, and the nucleotide diversity varied 0.0009 to 0.0019, demonstrating their low genetic diversit . Analysis of molecular variance (AMOVA) showed that genetic variations mainly occurred within the populations(99.39%), the total genetic differentiation index (Fst) was 0.0061. The pairwise genetic differentiation index (Fst) ranged from -0.0228 to 0.0445, and the genetic distance among populations varied from 0.0012 to 0.0027, indicating that there was no significant genetic differentiation among six populations. The Neighbor- joining phylogenetic tree and network structure both showed that the haplotypes randomly distributed in six populations, without forming specific geographic calde. Both neutral tests and mismatch distribution anlysis indicate that the A.nobilis had experienced significant population expansion. The study showed that the genetic diversity of A.nobilis populations from freshwater lakes in Jiangsu province was relatively low, and their genetic structure tends to be homogenized. So, more measures need to be taken to improve the genetic diversity of A.nobilis.