合浦珠母贝2个野生种群的遗传多样性

Genetic diversity of two wild populations in Pinctada martensii

用形态特征比较与同工酶电泳分析相结合的方法 ,对产于我国北部湾和大亚湾的野生合浦珠母贝 (Pincta damartensii)的遗传多样性进行研究。结果表明 ,在贝壳形态方面 ,北部湾种群的平均壳长与壳高都略大于大亚湾种群 ,壳高与壳长呈乘幂相关 ,壳宽与壳长呈对数相关。大亚湾种群的壳宽指数、壳重指数和肥满度指标都大于北部湾种群。用聚丙烯酰胺梯度凝胶电泳检测由 2 6个位点编码的 12种同工酶 ,2种群都显示出较高的多态性 ,北部湾种群多态位点的比率为 38.4 6 % ,大亚湾种群则为 4 6 .15 %。都表现出明显的杂合子缺失现象 ,北部湾种群的平均杂合度 (0 .0 999)小于大亚湾种群 (0 .12 4 3)。 2种群之间的遗传距离为 0 .0 15 9。本文还讨论了引起 2种群杂合子缺失现象的原因 ,并认为生化遗传分析的结果与 2个种群的形态特征是相关联的。

The genetic diversity of two wild populations of Pinctada martensii from Beibu Bay and Daya Bay in South China Sea were studied by comparison of their morphological characters and isozyme analysis. Morphologically,the mean shell length(L) and shell height(H) of Beibu Bay population (BBP) are slightly larger than those of Daya Bay population (DBP). The relationships between shell length and shell height can be described by a power function: H B=1.548 1 L B 0.900 1 (R 2=0 919 5,P<0.05) for Beibu Bay population;,H D=1.188 6 L D 0.975 6 (R 2=0 899 9,P<0.05) for Daya Bay population. The relationships between shell width (W) and shell length (L) are described by a logarithmic function: W B=19.86ln(L B)-61.716 (R 2=0 877 8,P< 0.05 ) for Beibu Bay population; W D=28.28ln L D-90.667 (R 2=0 846 9,P<0.05) for Daya Bay population. The indexes of shell width and shell weight and the condition factor value of DBP are higher than those of BBP. The electrophoretic analysis of 12 isozymes at 26 loci in both of the populations suggests significant genetic variation. The rate of polymorphic locus is 38.46% in BBP and 46.15% in DBP. Both of the populations indicate strikingly heterozygote deficiency. The mean heterozygosity value of BBP is 0.099 9,and that of DBP is 0.124 3; the genetic distance between them is 0.015 9. The authors also discuss the reasons for the deficiency of heterozygote and suggest that the result from biochemical analysis be correlated with the morphological characters.