北部湾光裸星虫3个地理群体遗传多样性

利用微卫星DNA分子标记对广东湛江乌石(ZJ)、广西北海山口(BH)与越南锦普(JP)3个光裸星虫(Sipunculus nudus)野生群体的遗传多样性进行分析。结果表明, 20个微卫星座位中有3个位点(Snu08、Snu10、Snu14)呈现单态, 17个多态微卫星座位中的等位基因数介于2～9之间, 多态信息含量(PIC)介于0.097～0.797之间。每个群体中有5个位点显著偏离了Hardy-Weinberg平衡, 在位点Snu18上3个群体均偏离Hardy-Weinberg平衡。3个光裸星虫野生群体均表现出中等程度的遗传多样性水平, 锦普群体遗传多样性水平高于北海和湛江群体。群体间F-统计量分析表明, 群体遗传分化处于低等分化水平, 差异不显著(F_st=0.019～0.049, P>0.05); 基于D_A遗传距离构建的NJ和UPGMA聚类树均显示, 地理位置相邻的群体聚在一起。研究表明, 3个光裸星虫地理群体均具有中等的遗传多样性, 杂合度均偏低, 群体间存在较大的基因流, 杂合子明显缺失; 群体间已产生遗传分化, 但分化水平还较低。

genetic diversity in three wild stocks of Sipunculus nudus Linnaeus, 1766 in Beibu Gulf

We evaluated the genetic diversity of three wild populations Zhanjiang (ZJ), Beihai (BH), Jingpu (JP)] of Sipunculus nudus in the Beibu Gulf using 20 microsatellite DNA loci. We calculated the allele numbers, effective allele numbers, expected heterozygosity, observed heterozygosity and Hardy-Weinberg equilibrium. Three loci were monomorphic and 17 loci were polymorphic. Five loci in each population deviated significantly from Hardy-Weinberg equilibrium. The locus Snu18 exhibited significant deviation from Hardy-Weinberg equilibrium in all 3 populations. Though diversity was higher in JP than in BH and ZJ, F_st analysis across the stocks and loci revealed a low level of divergence. We constructed NJ and UPGMA clustering trees based on D_A genetic distance. The populations from nearby geographical locations were clustered together in both trees.