中国海南三亚大珠母贝不同年代种群的遗传变异研究

利用10个多态微卫星标记对中国海南三亚海域大珠母贝（Pinctada maxima）3个不同年代（2007、2009和2010）群体的遗传变异进行了分析，每个群体30个样品。10个位点共扩增出60个等位基因，平均每个位点6（2—8）个，3个群体分别丢失了1、2和4个稀有等位基因。平均期望杂合度（Hc）、平均多态信息含量（PIC）、平均Shannon多样性指数均呈下降趋势。各群体均存在一定程度的杂合子缺失。30个数据中（3个种群×10个位点）有18个偏离了Hardy—Weinberg平衡。两两群体间的平均近交系数（FIS）介于0．2273～0．2601之间，平均遗传分化指数（FST）介于0．0204～0．0462，遗传分化显著（P〈0．01）。结果表明，3个年代群体遗传多样性水平已经出现了逐渐降低的趋势，遗传结构存在显著差异，近交程度增加，因此，人工繁育工作中应注意避免近亲繁殖和遗传多样性的降低。

Genetic variation in Pinctada maxima populations of different year-class from Sanya, Hainan,China

With 10 polymorphic microsatellite markers, we studied the genetic variation in silver-lip pearl oyster （Pinctada maxima） populations of 3 year-classes （2007, 2009, 2010） from Sanya, Hainan, China. For each population we collected 30 samples, and 60 alleles were amplified among 10 loci using PCR, each locus including 2 -8 alleles. Three populations lost 1, 2 and 4 rare alleles, respectively. The average expected heterozygosity, PIC value and Shannon＇s information index all decrease. Moreover, there is an o- verall deficit of heterozygotes for the populations. Eighteen out of 30 loci are deviated from Hardy-Weinberg equilibrium. The average pairwise inbreeding coefficient Fis ranges from 0. 227 3 to 0. 260 1 , and the pairwise Fsw value ranges from 0. 020 4 to 0. 046 2, indica- ting a significant genetic differentiation （ P 〈 0. 01 ）. This study suggests that the genetic diversity and the degree of inbreeding for the populations of 3 year-classes decrease from generation to generation, and their genetic structures differ from one another significantly.Thus, it is necessary to avoid inbreeding and to maintain the genetic diversity during artificial reproduction.