Microsatellite Polymorphism and the Population Structure of the Black Tiger Shrimp (Penaeus monodon) in Thailand

Genetic variation and differentiation of Thai Penaeus monodon from five geographic locations (Chumphon, Trad, Phangnga, Satun, and Trang) were investigated using five microsatellite loci (CUPmo18, Di25, Di27, CSCUPmo1, and CSCUPmo2). The number of alleles across the five loci ranged from 19 to 30, and heterozygosities ranged from 0.49 to 0.95. The mean number of alleles and effective number of alleles per locus were 21.0 to 26.6 and 13.1 to 20.4, respectively. The average heterozygosity across all investigated samples was 0.78, indicating high genetic diversity in this species. Geographic heterogeneity analysis of the results from two of the loci, CUPmo18 and Di25, showed significant differences among the Gulf of Thailand (Trad and Chumphon) but not the Andaman samples. Comparison between regions revealed significant heterogeneity of the Andaman and Trad P. monodon (P <.001), whereas those from Chumphon and the Andaman were genetically similar (P >.05). Significant genetic differentiation was consistently observed between the Andaman-Trad samples (F(ST) = 0.0101, P <.0001) and the Chumphon-Trad samples (F(ST) = 0.0101, P <.0001). On the basis of our analyses, the investigated samples from five geographic locations were allocated to three distinct populations composed of the Andaman Sea (A), Chumphon (B), and Trad (C).