草鱼野生群体和人工繁殖群体遗传结构的比较研究

采用新型分子标记SRAP(Sequence-related amplified polymorphism)对草鱼(Ctenopharyngodon idella)1个野生群体(来自邗江草鱼国家级原种场)和2个人工繁殖群体(分别来自淡水中心良种场和无锡前洲水产良种场)进行遗传多样性分析,从不同引物组合中筛选出8组条带清晰、多态性丰富的引物组合,每个引物组检测到的位点数为12～21个,在3个草鱼群体中共检测到120个位点,其中多态性位点有92个,多态位点比例为76.67%,显示了较高的多态性。野生群体与2个人工繁殖群体多态位点比例分别为67.62%、59.81%、53.33%,平均杂合度分别为0.214 3、0.211 0、0.172 2;邗江野生群体与2个人工繁殖群体间的遗传距离分别为0.098 0、0.115 9,两个人工繁殖群体间遗传距离为0.095 9。结果表明,草鱼人工繁殖群体遗传多样性有所下降。比较各扩增位点显性基因型频率在不同区间的分布发现,人工繁殖群体低频位点明显减少而隐性纯合基因位点显著增加。

Genetic structure analyses of grass carp populations between wild and cultured ones

Sequnce-related amplified polymorphism(SRAP) was used to compare genetic structures among three populations of Ctenopharyngodon idella-one wild and two cultured populations.Samples of wild population were collected from Jiangsu Hanjiang National Four Major Chinese Carps breeding Farm and the two cultured populations from Freshwater Fisheries Research Center Aquatic Breeding Plants and Wuxi Qianzhou Aquatic Breeding Plants.Eight primer combinations,which produced good amplified patterns,were sorted out.One hundred and twenty amplified loci were obtained from the three populations,among which 92 were polymorphic.The percentage of polymorphic loci in Hanjiang population(HJ),Freshwater Fisheries Research Center population(YC) and Qianzhou population(QZ) is 67.62%,59.81% and 53.33%,respectively.The results indicated that genetic polymorphism decreased in two cultured grass carp populations.The average heterozygosis of three populations were 0.2143,0.2110 and 0.1722,respectively.The genetic distance between Hanjiang wild population and two cultured ones were 0.0980 and 0.1159,while the genetic distance between two cultured ones was 0.095 9.The noticeable decrease in the number of rare loci and the increase in the number of homozygous recessive loci in the cultured population suggested a considerable loss of low frequency alleles in the cultured populations,which may have resulted from small effective population sizes during artificial breeding.