中间球海胆群体遗传学研究中AFLP引物数量及样本量的选择

采用10,20,30,40,50,60,70,80共8个样本量梯度,随机选择并逐步增加AFIP引物组合,研究了AFLP标记数量及样本量对中间球海胆(Strongylocentrotus intermedius)群体遗传学指标的影响。结果表明:基因多样性指数(H)、Shannon氏指数(I)和多态位点比例(PP)3个遗传学指标对样本量的敏感程度不同,PP指标受样本量影响较大,样本量≥50个时方稳定,H指标在样本量≥30时稳定下来,而I指标在样本量≥20时即不再出现显著差异。共采用6对A FIP引物对80只海胆进行群体遗传学研究。通过每1对、每2对、每3对、每4对、每5对引物组合分别计算各遗传学指标,发现前二者所得各值之间以及其与对照值(6对引物所得值)之间存在显著差异,而每三对引物组合计算的各指标间不存在显著差异。据此推测,对中间球海胆进行AFLP标记研究中,样本数量最好不少于50个;而若样本量足够大(80个个体),则至少需要3对AFLP引物(或不少于100个标记),方能对海胆群体进行准确的遗传学评价。

Selection of AFLP primer number and sample size in population genetic study of Strongylocentrotus intermedius

This study examines the effects of sample size and number of AFLP primer pairs on genetic structure in cultured sea urchin(Strongylocentrotus intermedius).8 different sample sizes,10,20,30,40,50,60,70 and 80 individuals,were used to calculate the genetic parameters including Nei’s gene diversity(H),Shannon’s information index (/) and percent of polymorphic loci(PP).These indicators increased dramatically along with the increasing of sample sizes and then held a stable trend.When the sample sizes were equal to,or more than 50,PP showed no significant differences with the sample size rising.H and I showed no significant differences when there were more than 30 and 20 individuals,respectively.The genetic parameters were also calculated from band information detected by each of one,two, three,four and five AFLP primer pairs,and those calculated from six AFLP primer pairs were considered as control.H,I and PP were all showed significant differences between results from one or two primer pairs and those from control.When the numbers of AFLP primer pairs were equal to or more than three,all genetic parameters showed no significant differences.Accordingly,we suggested that when AFLP markers were used to estimate genetic diversity of sea urchin population,the minimum sample size should not be less than 50 and at least 3 AFLP primer pairs(or,more than 100 loci) were required when the sample size was large enough(80 individuals).