基于微卫星标记对长江下游鲢遗传多样性现状的分析

Genetic diversity of silver carp (Hypophthalmichthys molitrix) in lower reaches of Yangtze River based on microsatellite markers

  • 摘要: 为了解长江下游鲢 (Hypophthalmichthys molitrix) 遗传多样性和遗传结构分布,该研究利用微卫星分子标记结合毛细管电泳技术,通过对2017—2019年长江湖口、安庆、芜湖、当涂、镇江、靖江、张家港和常熟8个江段鲢野生群体共327 份DNA进行基因分型与遗传多样性相关分析,比对了其遗传多样性、遗传分化和遗传结构情况。结果显示,长江下游8 个群体总体遗传多样性水平较高,但群体内缺乏足够的杂合子,8个群体等位基因数 (Na)介于6.0~12.3,有效等位基因数(Ne)介于3.94~6.10,观测杂合度 (Ho)和期望杂合度 (He)分别介于0.617~0.719和0.658~0.774,无偏期望杂合度(uHe)介于0.671~0.782,Shannon's信息指数 (I)介于1.38~1.86,群体内近交系数 (F)介于0.001~0.174;遗传分化分析显示Fst (F-statitics values) 介于0.006~0.068,基因流 (Nm)介于3.41~41.9,遗传距离 (D)介于0.001~0.106,湖口群体与其他群体表现出中等程度的遗传差异,其他群体间遗传差异很小,分子方差分析显示变异主要来自群体内 (97.6%);遗传结构分析显示湖口群体有不同于其他群体的基因库。结果表明江湖连通性可能对于鲢在湖口江段展现独特遗传分化特征具有积极意义,而形成这种种群分化究竟是由于地理距离的空间隔离还是生境差异的生理屏障有待进一步探究。

     

    Abstract: In order to understand the genetic diversity and distribution of silver carp (Hypophthalmichthys molitrix) in the lower reaches of the Yangtze River, we used simple sequence repeats (SSR) combining with capillary electrophoresis to analyze 327 DNA samples of silver carp from eight wild populations in Yangtze River sections (Hukou, Anqing, Wuhu, Dangtu, Zhenjiang, Jingjiang, Zhangjiagang and Changshu sections) from 2017 to 2019, so as to investigate their genetic diversity, genetic differentiation and genetic structure. The results show that the genetic diversity of the eight populations was high. However, heterozygotes were not enough in the populations. The number of alleles ranged from 6.00 to 12.3, while the number of effective alleles ranged from 3.94 to 6.10. The observed heterozygosity and expected heterozygosity ranged from 0.617 to 0.719 and from 0.658 to 0.774, respectively. The unbiased expected heterozygosity ranged from 0.671 to 0.782. The Shannon's information index ranged from 1.38 to 1.86, and the inbreeding coefficient ranged from 0.001 to 0.174. The genetic differentiation analysis shows that the Fst value ranged from 0.006 to 0.068, while the gene flow ranged from 3.41 to 41.9. The genetic distance ranged from 0.001 to 0.106. Hukou population showed a moderate degree of genetic difference with the other populations, while the genetic differences among the other populations were small. Analysis of molecular variance shows that the variation mainly was within the population (97.6%). Genetic structure analysis shows that Hukou population had different gene pool from the other populations. The river-lake connectivity may be of positive significance for silver carp to show unique genetic differentiation characteristics in Hukou section of the Yangtze River. Therefore, whether the formation of this population differentiation is caused by the spatial isolation of geographical distance or the physiological barrier of habitat difference needs to be further studied.

     

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