长江、黄河和辽河水系中华绒螯蟹野生和养殖群体遗传变异的微卫星分析

我国中华绒螯蟹(以下简称河蟹)养殖主要集中在长江、黄河和辽河流域,经过多年的人工养殖、跨流域引种和增殖放流等活动可能会对其遗传特性造成一定的影响,因此本研究利用29个微卫星标记对3个水系的野生和养殖群体进行了遗传特征分析。结果表明:(1)6个群体均表现出较高的遗传杂合度水平(Ho=0.702—0.744),香农信息指数(I)显示6群体的遗传多样性水平依次为:长江野生长江养殖黄河野生辽河养殖黄河养殖辽河野生。(2)分子方差分析(AMOVA)结果显示,来源于种群内个体间和个体内部的变异分别为14.02%和85.88%,群体间的遗传分化处于较低水平(FST0.05);(3)瓶颈效应和遗传结构分析显示,所有群体近期均经历过有效种群的降低,且6种群内个体的遗传组成混杂。综上所述,三水系野生和养殖群体均具有较高的遗传多样性,长江和黄河野生群体的遗传多样性略高于养殖群体;三水系河蟹野生群体的遗传分化与地理距离具有一定的相关性,长江养殖群体、黄河野生及养殖群体间的遗传分化较小可能与其跨流域引种及养殖群体逃逸造成其种质混杂有关。

GENETIC VARIATION OF WILD AND CULTURED POPULATIONS OF CHINESE MITTEN CRAB ERIOCHEIR SINENSIS FROM THE YANGTZE, HUANGHE, AND LIAOHE RIVER BASINS USING MICROSATELLITE MARKER

The major culture area of Chinese mitten crab Eriocheir sinensis are located in the drainage basins of Yangtze, Huanghe and Liaohe rivers in China.After years of artificial breeding, the inbreeding depression and adverse selection for small size broodstock crabs, eventually resulted in the genetic degeneration for pond-reared populations of E.sinensis.Moreover, the ultilization of pond-reared crab seeds and broodstock for stock enhancement may have some negative impacts on the genetic characteristics of natural populations in three rivers.The current study was firstly conducted to select 29 microsatellite loci with high polymorphism for the evaluation of genetic characteristics of E.sinensis, then to assess the genetic diversity and population structure of the wild and cultured E.sinensis populations from three major river systems, i.e.Yangtze wild population (YW), Yangtze pond-reared population (YP), Huanghe wild population (HW), Huanghe pond-reared population (HP), Liaohe wild population (LW), Liaohe pond-reared population (LP).The results show that: There were higher levels of heterozygosity (H_o=0.702-0.744) for six populations;according to Shannon information index (I), the order of genetic diversity for six populations was the YW > YP > HW > LP > HP > LW.The coefficient of genetic differentiation F-statistic (FST) among populations indicated the low divergence was existed among the populations (F_ST<0.05).Bottleneck analysis indicated that the effective number of each populations decreased recently while population genetic structure analysis showed that the individual genetic compositions of each population were miscellaneous for six populations.In summary, the six populations have the highly genetic diversity, and genetic diversity of YW and HW are slightly higher than their reared stocks.There is a certain relationship between the genetic differentiation and geographic distance of three wild stocks.The slight genetic differentiation among YW, HP and HW indicated the germplasm hybrid maybe exist in those populations because of blind introduction and escape of reared populations.