| Population is the basic unit of the modern taxonomy, fish resources change was took population as the unit. Studing populations of fish is the basic premise of fish biology study, and is an important research topic resources of biology.Nowadays, The situation of the South China Sea dispute is complicated, it will also become the direction of the future to joint development of the South China Sea resources, so accurate discriminating of fish populations is conducive to the management in the future. Based on the South China Sea red bigeye(Priacanthus macracanthus) as the research object, this study was using mitochondrial DNA sequence analysis as marker, distinguishing population of Priacanthus macracanthus from every sampling sites of the south and north of the South China Sea, filling the blank of the fish genetic studies. Results can use to protect the weakening of the South China Sea germplasm resources, provide the theory basis for protection of diversity of biology, what’s more, it is important to the scientific management to marine stock enhancement, protection of transboundary fish, and strive for fishing quotas.Specific content is as follows:1. In the present study, we examined the population genetic structure of red bigeye Priacanthus macracanthus from the South China Sea which include coastal waters of Beibu Gulf,Sanya, Maoming, Zhuhai, Shantou and the Southwest of Nansha. Sequences of the mitochondrial control region(D-loop) were amplified by polymerase chain reaction. Fragments of 729 bp of the mitochondrial D-loop were sequenced for Priacanthus macracanthus along the coast of the South China Sea. The content of bases A, C, T, G,is 31.8%, 19.1%, 34.1% and 19.1% respectively, A + T content is 65.9%, C + G content is 34.1%, showing obvious AT preferences and anti G bias.Detected 101 mutations, 94 nucleotide polymorphism loci, defines the 172 haploid types. All 6 groups were characterized with high haplotype diversity(0.980 5 ~ 0.997 1)and low nucleotide diversity(0.048 2 ~ 0.060 9). MJ network figture found advantage haploid types: Hap10, Hap29 and Hap39, but found no significant geographical distribution characteristics.Pairs of Fst analysis shows that the Fst value between the sampling sites of the south China sea is between ―0.012 6~0.014 6, less than 0.05. Phylogenetic analysis and analysis of molecular variances revealed no significant genealogical clades of samples corresponding to sampling localities. Both neutrality tests and mismatch distribution analyses indicated a recent population expansion in P. macracanthus in the late Pleistocene. So P. macracanthus of the South China Sea belongs to one population. The research results provided the basis for the fishery resources sharing and quotas winning of China and south China sea surrounding countries.2. The population genetic structure and the genetic diversity of the demersal economic fish Priacanthus macracanthus from South China Sea were examined based on 684 bp segment of the mitochondrial cytochrome b(Cyt b). A total of 264 individuals were collected from the north of the South China Sea and the Southwest of Nansha. The bases of A, T, C, G, is 22.7%, 28.4%, 33.4%, 28.4%, and A + T similar to C + G content, 51.1% and 48.9% respectively. Polymorphic loci was 92, accounting for 13.45% of all sequences. Defining 90 haplotypes. Genetic diversity showed high diversity of haploid type(0.813 0 ~ 0.901 2) and low nucleotide diversity(0.004 0 ~ 0.005 3); Haploid type network diagram found advantages haploid type of Hap1, Hap2, Hap4 and Hap6, but did not see a significant geographical features. Pairs of Fst analysis shows that only the value of the Nansha sampling point with Sanya and the Beibu gulf exceeds 0.05, respectively significantly 0.065 4, 0.088 7, 0.062 4, the others are between-0.018 5 and 0.037 2, which are less than 0.05, and the value was not significant. Analysis of molecular variance(AMOVA) indicated that most of the differentiation occurred within populations(98.75%), and only 1.25 % occurred among populations. The calculation of genetic parameters suggested that genetic differential index(Fst) between populations was 0.012, and the degree of genetic differentiation was low. Molecular tree constructed by Neighbour-joining method showed that the seven groups of Priacanthus macracanthus were panmiotic population, there were not obvious type branch. Phylogenetic analysis and molecular analysis of variance analysis showed that the fish had a higher genetic homogeneity, the genetic differentiation was not significant, no obvious geographical branch or clustering. Neutral detection and analysis found that asymmetric distribution, and it happended population expansion to Priacanthus macracanthus of the South China Sea in the late Pleistocene. The results indicated that great gene flow existed among populations and the genetic diversity between populations was at quite high level. Although the continental shlef of the south China sea is broad and the seabed of that is complex and diverse, the result suggest that Priacanthus macracanthus maybe belong to one single population in the South China Sea. |
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