湖北钉螺扩增片段长度多态性分子标记遗传多样性研究的合理样本量与分子位点数

Appropriate sample size and molecular marker loci in the study of genetic diversity of Ocomelania hupensis

目的 探讨用扩增片段长度多态性(AFLP)分子标记研究湖北钉螺遗传多样性的合理样本量与分子位点数。方法 选取湖南省岳阳市遗传变异较大的肋壳钉螺为研究材料，用AFLP方法对钉螺基因组DNA进行扩增，然后分析湖北钉螺样本量和分子位点数与遗传变异信息可靠性的关系。结果 湖北钉螺样本量和分子位点数与遗传多样性信息的可靠性之间存在明显的关系。当样本量低于7只时，AFLP总位点数、多态位点数、多态位点频率、Nei’s基因多样性指数和Shannon’s信息指数变化很大，而当样本量超过30只时，这些指标值的变化趋于平稳。当AFLP分子位点数低于128时，多态位点频率、Nei’s基因多样性指数、Shannon’s信息指数以及这两个指数的标准差变化相当剧烈，当分子位点数超过338时，这些指标值的变化趋于稳定。结论 在用AFLP分子标记技术研究湖北钉螺的遗传多样性时，每个钉螺种群内的样本量最好不应低于30只，用于研究分析的分子位点数最好不低于338个。

Objective To explore the reasonable sample size and the number of molecular marker loci in the study of amplified fragment length polymorphism （AFLP） being used to analyze the genetic diversity of Ocomelania hupensis. Methods The ribbed-shelled snails coming from Yueyang, Hunan province, were selected to analyze the relationship of the number of AFLP molecular marker loci and sample size with the reliability of information on genetic variation for Ocornelania hupensis by AFLP method. Results Correlations found among the numbers of AFLP molecular marker loci and the sample size with reliable information on genetic variation for Ocomelania hupensis. When sample size was less than 7 individuals, the total number of AFLP loci, the number of polymorphic loci, Nei＇s gene diversity and Shannon＇ s information index appeared great changes. However, when sample size was bigger than 30 individuals, the values of these indices tended to be stabilized. When the number of AFLP loci was less than 128, the frequency of polymorphic loci, Nei＇s gene diversity,Shannon＇s information index and the standard deviation of these two indices changed greatly. Again, when the number of loci was bigger than 338, the values of these indices tended to be stabilized. Conclusion When the genetic diversity of Ocomelania hupensis were analyzed by AFLP method, the sample size coming from each snail population should not be less than 30 individuals and the number of molecular loci analyzed not less than 338.