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

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 stoc