样本量与东方蜜蜂微卫星DNA遗传多样性参数稳定性的关系

Relationship between sample size and the stability of genetic diversity parameters of microsatellite DNA in the eastern honeybee

准确地评估遗传多样性是研究遗传多样性和保育遗传学的重要前提.遗传多样性研究可靠性的影响因素之一就是采样策略中的最适样本量.本研究采用微卫星标记研究样本量对遗传多样性参数检测稳定性的影响.以5个东方蜜蜂种群为试验材料,设置10群为样本梯度,10~150群共15个梯度样本量,分析微卫星标记常用的7个遗传多样性参数与样本量之间的关系.结果表明:(1)每个参数反映的遗传多样性信息不同,能反映总体遗传多样性所需要的样本量也不同.(2)反映种群遗传变异丰富度的等位基因数和等位基因丰富度极易受样本量的影响,样本量为150群时能检测到总体91%以上的丰富度;反映种群遗传变异均匀度的期望杂合度、观察杂合度、有效等位基因数和多态信息含量的最小样本量分别为40、70、40和60~80群;同时反映遗传丰富度和均匀度的香农指数最小样本量为60~70群.综合考虑所有参数,建议在充分保证样本代表性的前提下,研究蜜蜂遗传多样性的样本量最少60群,最好在80群以上;重点关注等位基因数和等位基因丰富度等参数的研究,样本量应在150群以上;重点关注期望杂合度和有效等位基因数的研究,样本量可在40群以上.

Accurate assessment of genetic diversity is prerequisite for the studies on genetic diversity and conservation genetics, in which optimal sample size is critical for the reliability. To investigate the effect of sample size on the stability of genetic diversity parameter based on microsatellite markers, 5 representative populations of Apis cerana were all divided into 15 sampling groups, where each group consisted of 10-150 colonies based on a sample size gradient of 10 colonies. Then the relationship between the sample size of A.cerana and 7 genetic diversity parameters commonly used in microsatellite analysis were investigated. The results showed that:(1) due to the different information of genetic diversity provided by each parameter, the sample size required to calculate total genetic diversity was different.(2) The number of alleles and allelic richness, indicating the richness of genetic variation, were highly susceptible to sample size, and the total richness above 91% was only detected when the sample size was 150 colonies. To reflect the uniformity of population genetic variation, the minimum sample sizes for the parameters of expected heterozygosity, observed heterozygosity, effective allelic number, and polymorphic information content were 40, 70, 40 and 60-80 colonies, respectively. While Shannon′s index needed a minimum sample size of 60-70 colonies to reflect both genetic richness and evenness. Taken all the parameters into consideration, genetic diversity analysis of A.cerana needed a sample size of at least 60 colonies and preferably more than 80 colonies on the premise of representative samples. For the parameters of number of alleles and allelic richness, sample size of more than 150 colonies was recommended, and study focusing on expected heterozygosity, effective allelic number needed a sample size of 40 colonies at least.