罗氏沼虾种群SSR分析中样本量及标记量对遗传多样性指标的影响

利用60对微卫星分子标记分别对罗氏沼虾3个养殖群体进行遗传多样性分析,通过比较样本量及标记量对遗传多样性指标的影响,探讨最适宜的样本量及标记量。结果显示,样本量和标记量的大小均对遗传多样性指数有较大的影响,其中样本量与平均等位基因数和平均有效等位基因数呈高度正相关,与杂合度和Nei氏遗传多样性指数分别呈中度、高度相关,样本量为10~30时,遗传参数变化差异显著,样本量大于30,变化差异不显著;标记量与遗传参数也存在不同程度的相关性,标记量为5~25时,各遗传多样性指数变化有明显差异,标记量大于25时,各遗传参数变化较小,多态信息含量不同的标记直接影响到群体遗传参数。性别对群体遗传多样性指标无显著性影响。研究表明,应尽可能选择多态信息含量高的微卫星分子标记开展罗氏沼虾群体遗传多样性分析,可不考虑样本性别,样本量不宜小于30,标记量不宜少于25。

Effects of sample size and loci number on genetic diversity index in Macrobrachium rosenbergii with microsatellite markers

As assessment of genetic structure of population is the key point of aquatic animal breeding, the selection of sample size and loci number is the first step of correct evaluation of population genetic structure. Here, we solved the problem from an analysis of genetic diversity of three breeding groups of Macrobrachium rosenbergii at 60 polymorphic microsatellite loci. The results show that selection of different sample sizes and loci numbers both had a great effect on the genetic diversity index. The sample size was positively correlated with the average number of alleles and the average effective number of alleles, and the sample size was moderate and highly correlated with heterozygosity and Nei′s genetic diversity index, respectively. Only when the sample size exceeds 30, they tend to be stable. When we select the loci, we found the different polymorphism information contents also directly affect the accuracy of the genetic parameters. When the loci number was 5–25, there was a significant difference in the genetic diversity index(P<0.05). When the loci number was more than 25, the genetic parameters changed little(P>0.05). So, we suggested that when microsatellite markers were used to estimate genetic diversity of population as far as possible to choose high polymorphism information content and we can′t consider sample gender, meanwhile the minimum loci number and sample size are needed to exceed 25 and 30, respectively.