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利用8个微卫星标记对引进的SPF凡纳滨对虾G0和两个养殖群体(G1,G2)进行遗传多样性分析。8个座位共获得64个等位基因,位点的等位基因数在5~l3之间。多态信息含量PIC在0.405 2~0.869 3之间,其中有6个位点为高度多态位点,适合于多态性分析。8个座位丢失的和新产生的等位基因共30个,占总数的47%。3个群体的平均观测杂合度分别为0.193 8、0.196 1、0.232 5,说明3个群体的遗传多样性较低。对近交系数Fis分析显示3个群体中存在近交,通过对哈迪温伯格平衡检验,显示所有座位均显著偏离平衡,存在杂合子缺失。通过配对Fst和Ne i遗传距离分析,显示3个群体之间有明显的遗传分化,说明种群结构发生了明显的遗传变异,变异可能来自于突变、随机漂变和选择的共同作用。实验结果能够很好地解释经过若干群体选育后,子代群体发生种质退化的现状,由此建议综合采用遗传育种的方法从引进的亲虾中筛选出性状优良稳定的仔虾作为虾苗。
Eight microsatellite markers were used to analyze the genetic diversity of introduced P. grisea G0 and two cultured populations (G1 and G2). A total of 64 alleles were obtained in 8 seats, and the number of alleles at 5 loci was between 5 and 13. The polymorphism information content (PIC) ranged from 0.405 2 to 0.869 3, of which 6 loci were highly polymorphic and suitable for polymorphism analysis. A total of 30 lost and newly generated alleles were found in 8 seats, accounting for 47% of the total. The average observed heterozygosities of the three populations were 0.193 8, 0.196 and 1.3232, respectively, indicating that the genetic diversity of the three populations was low. Inbreeding coefficient Fis analysis showed that inbreds were present in three of the populations, and a balanced heterogeneity test of Hardy Weinberg showed that all the loci were significantly off-balance with loss of heterozygotes. Paired-pair Fst and Ne i genetic distance analysis showed that there was obvious genetic differentiation among the three populations, indicating that obvious genetic variation occurred in the population structure. The variation may come from the combination of mutation, random drift and selection. The results of the experiment can well explain the status of germplasm degeneration in the offspring population after breeding by several groups. Therefore, it is recommended to select the larvae with good and stable characters from the introduced broodstock as the shrimp seed by comprehensive genetic breeding method .