北部湾光裸星虫3个地理群体遗传多样性

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

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(Fst=0.019～0.049,P>0.05);基于DA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。

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,effec-tive 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,Fst analysis across the stocks and loci revealed a low level of divergence.We constructed NJ and UPGMA clustering trees based on DA genetic distance.The populations from nearby geographical locations were clustered together in both trees.