基于CO I和Cyt b序列的丹江口水库鲢群体遗传结构特征分析

有效的人工增殖放流应监控放流群体和野生群体的遗传结构特征，以避免放流群体对天然群体遗传多样性的负面影响。本研究利用线粒体CO I和Cyt b基因分析了丹江口鲢库区、鲢亲本和鲢子代3 个群体的遗传结构特征。分析结果显示，104 条646 bp线粒体CO I序列中共检测到多态位点15 个，简约信息位点5 个，单一变异位点10 个，定义了7 个单倍型，单倍型多样性为0.544~0.676，核苷酸多样性为0.00221~0.00254；103 条1058 bp线粒体Cyt b序列中共检测到多态位点19 个，简约信息位点13 个，单一变异位点6 个，定义了14 个单倍型，单倍型多样性为0.609~0.714，核苷酸多样性为0.00262~0.00424，总体上处于较高单倍型多样性和较低核苷酸多样性。CO I和Cyt b序列遗传距离、遗传分化指数以及基因流分析结果显示，群体间遗传距离为0.002（CO I）、0.003~0.004（Cyt b），总的遗传分化指数为-0.00468（P>0.05）（CO I）、0.03180（P>0.05）（Cyt b），差异均不显著，群体间基因流为14.69～41.47（CO I）、5.49～40.47（Cyt b），分子方差分析（AMOVA）结果表明群体的遗传变异主要来自群体内。单倍型聚类关系树表明，3 个鲢群体间均存在共享单倍型，不同地理群体间单倍型散乱分布于各支，未形成地理群体的聚集。以上分析结果显示，3 个鲢群体间不存在明显的遗传分化，表明增殖放流鲢群体与丹江口库区野生群体的遗传多样性和遗传结构相近，可开展增殖放流。本研究结果可为丹江口鱼类增殖站鲢群体的增殖放流提供科学依据。

Genetic Structure Analysis of Hypophthalmichthys molitrix Populations in Danjiangkou Reservoir Based on Mitochondrial CO I and Cyt b Sequences

Effective artificial breeding and restocking should monitor the genetic structure characteristics of the released population and the wild population to avoid the negative impact of the released population on the genetic diversity of the natural population. This study used mitochondrial CO I and Cyt b genes to analyze the genetic structure characteristics of three H. molitrix populations in Danjiangkou Reservior. In 104 mitochondrial CO I sequences with a length of 646bp, 15 polymorphic sites, 5 parsimony information sites and 10 single variant sites were detected, which defined 7 haplotypes. The haplotype diversity is 0.544~0.676, the nucleotide diversity is 0.00221~0.00254. In 103 mitochondrial Cyt b sequences with a length of 1058bp, 19 polymorphic sites, 13 parsimony information sites and 6 single variant sites were detected, which defined 14 haplotypes. The haplotype diversity is 0.609~0.714, the nucleotide diversity is 0.00262~0.00424, which is generally at a high haplotype diversity level and a low nucleotide diversity level. Genetic distance between populations is 0.002 (CO I), 0.003~0.004 (Cyt b), and the total genetic differentiation index (Fst) is -0.00468 (P>0.05) (CO I), 0.03180 (P>0.05) (Cyt b), indicating that there is no significant genetic differentiation among the H. molitrix populations. AMOVA analysis shows that the genetic variation of the population mainly comes from within the population. The haplotype cluster relationship tree shows that there are shared haplotypes among the three H. molitrix populations, and the haplotypes among different geographic populations are scattered in each branch, and no geographic clusters are formed. The above analysis results show that there is no genetic differentiation among the three H. molitrix populations, indicating that the current breeding and releasing silver carp population has no impact on the genetic diversity and genetic structure of the wild population in the Danjiangkou reservoir area. The results of this study can provide a scientific basis for the artificial breeding and restocking of H. molitrix populations at Danjiangkou reservoir.