尼罗罗非鱼Oreochromis niloticus、奥利亚罗非鱼O.aureus和红罗非鱼O.sp.群体遗传多样性的比较

Comparison of genetic diversity among stocks of Oreochromis niloticus,O.aureus and red tilapia based on microsatellite DNA

用9对微卫星引物对尼罗罗非鱼Oreochromis niloticus、奥利亚罗非鱼O.aureus和红罗非鱼O.sp.群体的遗传变异进行了比较研究。在3个群体109个个体中共检测到60个等位基因,3个群体的平均等位基因数分别为4.11、1.33和3.44,平均观测杂合度分别为0.528、0.056和0.491,平均期望杂合度分别为0.644、0.091和0.526,平均多态信息含量分别为0.580、0.077和0.466。杂合子偏离度D值分别为0.148、0.222和0.044,表明3个罗非鱼群体存在不同程度的杂合子缺失。卡方检验表明3个群体的大部分位点偏离Hardy-Weinberg平衡,存在遗传漂变现象。群体间遗传分化显著(遗传分化指数FST在0.329到0.656之间,P<0.01)。尼罗罗非鱼和红罗非鱼群体间的遗传距离最小(0.47)。上述分析表明,尼罗罗非鱼的遗传多样性最高,奥利亚罗非鱼的遗传多样性最低,群体间分化显著。表明尼罗罗非鱼和红罗非鱼尚具有一定的选育潜力,而奥利亚罗非鱼遗传多样性低,不利于选择育种,需要引进新的种群。

To provide genetic information for the purpose of selective breeding,comparison of genetic variability among the three cultured stocks of Oreochromis niloticus,O.aureus and red tilapia O.sp.was made using nine microsatellite loci.In total 60 alleles were detected from 109 individuals.The mean numbers of alleles were 4.11,1.33 and 3.44 with average polymorphism information contents being 0.580,0.077 and 0.466,respectively,for the Nile,aurea and red tilapia stocks.The observed heterozygosities averaged 0.528,0.056 and 0.491,respectively,for the three cultured stocks,while the expected heterozygosities averaged 0.644,0.091 and 0.526,respectively.D values of heterozygote deviation were 0.148,0.222 and 0.044,respectively,showing heterozygote deficiency in the three tilapia stocks.Chi-square tests showed that most loci in the three stocks deviated from Hardy-Weinberg equilibrium,suggesting occurrence of genetic drift possibly due to founder effect.Significant genetic differences were observed among the three stocks（pairwise genetic differentiation index FST： 0.329 to 0.656,P〈0.01）.The genetic distance between O.niloticus and red tilapia was the lowest（0.47）.These observations indicated that O.niloticus has the highest genetic diversity,whereas O.aureus has the lowest;so there is still some selective breeing potential for O.niloticus and red tilapia,whereas new germplasms of O.aureus should be imported for supplement.