基于线粒体COI序列的江淮下游湖泊鲢群体遗传多样性和遗传结构分析

Genetic diversity and genetic structure of Hypophthalmichthys molitrix populations in the lower reaches of Yangtze and Huaihe River based on COI sequences

本研究采用线粒体COI序列为分子标记,探究了长江、淮河下游8个湖泊鲢(Hypophthalmichthys molitrix)群体的遗传多样性和遗传结构。通过PCR和测序技术,获得鲢COI基因序列片段。分析结果显示:COI序列片段长度为630 bp,243条COI序列共检出23个变异位点,定义14种单倍型,平均单倍型多样性(H_(d))和核苷酸多样性(P_(i))分别为0.692和0.00512。8个群体的单倍型多样性为0.508~0.803,核苷酸多样性为0.00241~0.00694,表明鲢群体的遗传多样性有较大差异。分子方差分析结果显示,遗传变异主要来自于群体内,遗传分化指数(F_(ST))为0.0083,表明群体间没有显著遗传分化。系统发育树和网络结构图显示,单倍型分化为2个分支,但群体没有形成特定的地理遗传结构。中性检验结果和歧点分布曲线表明,鲢群体没有显著偏离中性选择,群体大小保持相对稳定。

The genetic diversity and genetic structure of eight Hypophthalmichthys molitrix populations from Tai Lake,Ge Lake,Changdang Lake,Dianshan Lake,Gaoyou Lake,Hongze Lake,Luoma Lake and Jinsha Lake were investigated based on mitochondrial COI gene sequences to assess the genetic background of Hypophthalmichthys molitrix populations in the low Yangtze and Huai River.The COI sequences of 243 individuals of H.molitrix were obtained by PCR and sequencing technologies.The amplified fragment length of COI gene was 630 bp,23 variable sites were detected and 14 haplotypes were defined.The average haplotype diversity(H_(d))and nucleotide diversity(P_(i))of H.molitrix were 0.692 and 0.00512,respectively.The haplotype diversity of eight populations ranged from 0.508 to 0.803,and nucleotide diversity ranged from 0.00241 to 0.00694,which suggested that the genetic diversity was obvious different among eight H.molitrix populations.Analysis of molecular variance(AMOVA)showed that genetic variation mainly occurred within the populations.The genetic differentiation index(F_(ST))was 0.0083,which indicated there was no significant genetic differentiation among populations.The phylogenetic tree and network structure diagram showed that 14 haplotypes consisted of two clades,and there was no geographical genetic structure.The results of the neutral test and mismatch distribution curve demonstrated that H.molitrix populations had not significantly deviated from neutral selection and it remained relatively stable.This research results can provide useful basic data for the scientific protection of H.molitrix germplasm resources and stock enhancement in freshwater lakes.