Genetic heterogeneity of the giant tiger shrimp (Penaeus monodon) in Thailand revealed by RAPD and mitochondrial DNA RFLP analyses

Genetic diversity of the giant tiger shrimp (Penaeus monodon) collected fro m 5 areas, Chumphon and Trat (Gulf of Thailand), and Phangnga, Satun, and T rang (Andaman Sea), was examined by randomly amplified polymorphic DNA (RAP D) and mitochondrial DNA (16S ribosomal DNA and in intergenic COI-COII) pol ymorphism. A total of 53 polymorphic fragments from UBC299, UBC273, and UBC 268 was consistently scored across all samples. From the respective primers 26, 32, and 30 genotypes were generated. A 260-bp RAPD fragment venerated by the primer UBC268 was specifically observed in 95.8% of Trat P. monodon, suggesting that this RAPD could be used as a marker for comparing phenotyp ic performance of P. monodon from Trat and other geographic samples. In add ition, 37 mtDNA composite haplotypes were observed from restriction analysi s of the same P. monodon samples. High haplotype diversity (0.855) and nucl eotide diversity (3.328%) of Thai P. monodon were observed. Population diff erentiation of P, monodon between the Andaman Sea and Gulf of Thailand was clearly illustrated by both techniques (P < .0001). Nevertheless, contradic tory results Oil patterns of differentiation were observed between R monodo n within the Gulf Of Thailand. Analysis of nuclear DNA polymorphism (RAPD) indicated a genetically, significant difference between Chumphon and Trat ( P < .0001), whereas mtDNA polymorphism did not show differentiation between these samples (P = .0497). Under the presumption of selective neutrality o f these markers, biased female gene flow between Trat and Chumphon P. monod on may exist and be responsible for an anomalous differentiation pattern be tween these geographic samples.