Grass carp (Ctenopharyngodon idellus) are economically important in China, though wild populations have been in serious decline throughout the region. We used microsatellite markers to evaluate the genetic diversity amongst grass carp from four populations in three watersheds (Yangtze River, Pearl River, and Heilongjiang River). We selected 26 microsatellite markers and calculated heterozygosity, polymorphism information content (PIC), valid allele number, allele frequency, genetic distance, genetic similarity coefficient, and Hardy-Weinberg balance deflection index. There was a high degree of polymorphism within the markers in all three watersheds. The mean polymorphism information content (PIC) ranged from 0.581 3 to 0.638 6. Each microsatellite locus had 2-11 alleles (mean: 5.46). We identified a total of 154 alleles from all four populations, with a mean number of valid alleles of 3.455 6. The heterozygosity was between 0.711 4 and 0.804 5. FSt and AMOVA analysis across all populations and loci suggested that there was low level of divergence amongst the four populations (FST=0.03 1 73). The Jianli population and the Hanjiang population were grouped in one cluster, which was clustered with the Pearl River population. The Heilongjiang population was grouped in a separated cluster. Our results suggest that there is a high level of genetic diversity among grass carp from the three watersheds, and no obvious differentiation. Our results may be used to better manage the fishery for conservation of locally adapted populations.%选取26个微卫星标记对来自长江(监利、邗江)、黑龙江、珠江3个水系的4个野生草鱼(Ctenopharyngodon idellus)群体的遗传多样性进行了检测.结果表明,26个微卫星位点均为高度多态位点,草鱼4个地理群体的多态信息含量(PIC)平均值为0.581 3～0.638 6；共检测出141个等位基因,其中有102个为共有等位基因；每个位点有等位基因2～11个,平均等位基因5.46,平均有效等位基因3.455 6.4个地理群体野生草鱼的平均杂合度在0.7114～0.8045之间.群体间遗传固定指数(FsT)及AMOVA分析表明,群体间遗传分化并不显著(FsT =0.031 73).基于DA遗传距离构建的UPGMA聚类树表明,监利群体与邗江群体这两个长江水系野生地理群体聚为一支,然后与珠江群体聚为一支,黑龙江群体单独聚为一支.长江群体是原始群体.综上所述,三江水系野生草鱼具有较高的遗传多样性,4个群体之间遗传分化并不明显.
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