High genetic diversity and differentiation in three red tilapia stocks revealed by microsatellite DNA marker analysis

Red tilapia is thought to be the result of mutant-colored female Mozambique tilapias mating with male Nile, blue, or Zanzibar tilapias and cultured widely in Asia and central and South America. However, there is limited information about its genetic diversity and stock structure. In this study, we investigated the genetic variability of red tilapia stocks to provide fundamental knowledge for genetic improvement by molecular-marker-assisted selective breeding programs. Individuals (n = 180) from three stocks (Chinese Taiwan, Israel, and Malaysia) of red tilapia were genotyped based on 14 microsatellite markers. The results showed that all microsatellite loci were detected with high levels of polymorphism, with a mean number of 14.87 ± 3.85 alleles per locus in all stocks. Taiwan and Israel stocks showed higher heterozygosity than did the Malaysia stock. The F-statistic analysis showed that there was no significant genetic differentiation between the Taiwan and Israel stocks (P > 0.05), whereas there was highly significant genetic divergence in the other pairwise stocks (P < 0.01), suggesting that Taiwan and Israel stocks could be regarded as a single genetic group distinct from Malaysia stock. This result was in accordance with the UPGMA dendrogram based on Nei’s genetic distances of three stocks. The analysis of molecular variances (AMOVAs) revealed highly significant genetic variation among three stocks (P < 0.01) and accounted for 8.68% of the total variance. The results reported above were confirmed by Bayesian analysis in genetic structure simulation, which indicated a distinct genetic difference between Taiwan and Israel stocks compared with Malaysia stock.