草鱼种群SSR分析中样本量及标记数量对遗传多度的影响  

Effects of Sample Size and Loci Number on Genetic Diversity in Wild Population of Grass Carp Revealed by SSR

作　　者：李鸥[1,2] 赵莹莹[1,3] 郭娜[2] 鲁翠云[1] 孙效文[1] 

机构地区：[1]中国水产科学研究院黑龙江水产研究所,黑龙江哈尔滨150070 [2]大连水产学院生命科学与技术学院,辽宁大连116023 [3]上海海洋大学水产与生命学院,上海201303

出　　处：《Zoological Research》2009年第2期121-130,共10页动物学研究（英文）

基　　金：国家科技基础条件平台项目(2006DKA30470_005);国家重大基础研究计划(2004CB117405)

摘　　要：利用45对微卫星分子标记(SSR),以草鱼(Ctenopharyngodon idellus)自然群体为实验材料,探讨野生群体遗传多样性研究中所需的最适样本量与标记量。实验设置6个样本量梯度,9个标记量梯度。对等位基因数(Na)、有效等位基因数(Ne)、观察杂合度(Ho)、期望杂合度(He)等遗传多样性指标的变化趋势进行统计分析。结果表明,样本量、微卫星标记的数量和多态性水平对群体遗传多样性均有较大的影响,其中等位基因数与样本量大小呈显著正相关,而杂合度随标记量的增多而剧烈波动。当取样量大于40,标记量大于25时,各遗传参数值趋于稳定。因此,在应用微卫星标记对水产动物自然群体的遗传学研究中,要根据所研究种类的特点,尽可能采样40尾以上,采用25个以上标记,避免由人为选择的偏差对群体遗传多样性水平的正确评估所造成的影响。同时根据上述研究结果,对陕西草鱼自然群体进行了遗传多样性的评估,结果显示该群体平均等位基因数(MNA)、平均有效等位基因数、平均观测杂合度、平均期望杂合度分别为7.26、4.21、0.73、0.68,认为该群体具有较高的遗传多样性。Sample collection and marker selection are of primary importance in population genetic studies, and can greatly influence the analysis and interpretation of the data obtained. Microsatellite DNA sequences are the most revealing DNA markers available so far for inferring population structure and have been widely employed in genetic studies of populations. Nevertheless, few studies have specifically examined the effects of sample size and loci number on various genetic diversity measures in population genetic work using these markers. Here, we examined this issue using experimental data from an analysis of genetic diversity of wild populations of grass carp at 45 polymorphic microsatellite loci. The following genetic diversity measures were studied： number of alleles per locus （Na）, effective number of allele per loci （Ne）, observed hererozygosity （Ho） and expected heterozygosity （He）. We also tried to infer the theoretical minimum sample size and loci number needed for population genetic studies with microsatellite loci. The results are as follows： （1） Na and Mean number of allele over loci （MNA） are significantly affected by sample size. It increase according to the raise of the sample size, only when the sample size exceeds 40 it tends to be stable. The significant correlation between sample size and Na was observed and the correlation curve is Y=3.8403＋0.6376, r^2=0.967. However, there is no significant correlation between the mean value ofNe, Ho, He and the sample size. Mean value of rio, He fluctuate with the raise of the sample size, only when the sample size exceeds 40 it manifest a stable trend. （2） Evaluating of different genetic parameters with the makers of different polymorphism information content, a significantly different result were acquired. When PIC〉0.5, Na, Are, Ho, He were 3.6, 1.5934, 0.2824, 0.3540, While PIC〈0.5, Na, Are, Ho, He were 9.5, 5.9209, 0.8497, 0.8242 respectively. Accordingly, marker selecting strategy has much greater impact on evaluation of

关 键 词：样本容量 标记量 草鱼 自然群体 遗传多样性 微卫星分子标记 

分 类 号：S917.4[农业科学—水产科学]