Population Structure And Parentage Determination Of The Black Tiger Prawn (Penaeus Monodon)

To assess genetic structure and genetic diversity of the black tiger prawn (Penaeus monodon) in northern South China Sea, polymerase chain reaction (PCR) technique was used to amplify the elongation factor 1-alpha intron sequences region from 95 wild individuals of Penaeus monodon caught from Sanya, Shenzhen, Zhanjiang and Beihai in China. The PCR products were cloned. The positive cloned products were sequenced. As a result, about 216 bp nucleotide sequences that could be analyzed were obtained (the primer and some of the marginal sequences were exclude). Nucleotide sequences from northern South China sea area combined with sequences of the black tiger prawn of eastern Africa sea area and southeast Asian sea area populations (from Genbank) were analyzed. By using Clustal X to align and compare the sequences of the 207 individuals with each other, 188 variation sites were observed, of which there were 67 insertion sites or deletions, 121 polymorphic sites. Eighty nine haplotypes were detected from the elongation factor 1-alpha intron sequences, the Haploid diversity (Hd) was 0.975. The results showed that the gene diversity of Chinese sea area was minimum, but the gene diversity of eastern Africa sea area was the biggest. By analyzing popultion pairwise F_ST-valules, very strong differentiation was indicated between populations from the southeast Asian sea area and eastern Africa sea area (p<0.001), and this differentiation was also detected among northern South China sea area, eastern Africa sea area and southeast Asian sea area populations. In the molecular phylogenetic tree constructed in the method of UPGMA, southeast Asian sea area and northern South China sea area populations aggregated to a branch, eastern Africa sea area population aggregated another branch. Judged by sequence difference analysis, the genetic distance between northern South China sea area and eastern Africa sea area population was farther than the distance related between northern South China sea area and southeast Asian sea area population; among four population of northern South China sea area, Beihai population was more distantly related with Shenzhen, Hainan and Zhanjiang populations, while Shenzhen, Zhanjiang and Hainan populations were more closely related.One of the difficulties in selective breeding program is to maintain the parentage information. For the sake of obtaining the survival and growth traits of each family, the progeny from family groups are often isolated and raised in separate tanks until they are large enough for physical tagging. Owing to their high polymorphic features, microsatellies markers have turned into an essential tool for identifying parentage relationships among individuals and for obtaining pedigree information in aquaculture selective programs. So the application of microsatellite markers to parentage determination in aquaculture has been approved and has come into widely use in aquaculture. This study probed into the potential of microsatellite markers in parentage determination of Penaeus monodon families through controlling mating.We applied several pairs of microsatellite markers to P. monodon parentage determination on the basis of 7 families plain in pedigree. The result showed that 7 families could be distinguished effectively with the DNA fingerprinting maps of the several microsatellite loci. According to the genetic distance of each family calculated from the microsatellite data, the UPGMA tree be formed. The results were consistent with the nature of the 7 families, further proving that microsatellite markers could be used in the genetic analyses among the families. So both of the genetic markers could be used in the parentage determination of P. monodon.