Genetic Diversity and Differentiation of Fenneropenaeus Penicillatus in the Southeastern Coast of China
|Keywords||Fenneropenaeus Penicillatus allozyme AFLP SSR genetic diversity genetic differentiation|
Fenneropenaeus Penicillatus is an important marine commercial animal in China, but its resource is falling sharply recently because of serious over-exploitation,environmental degradation of spawning grounds and other factors.A book called China Species Red List, which was published in 2005, has classified it as an endangered[EN]species.Thus the protection of F. Penicillatus and rejuvenation are imminent. Nine F. Penicillatus stocks from nine different coastal areas were analyzed by allozyme ,AFLP ,SSR technologies in order to study the genetic diversity and differentiation of the nine F. Penicillatus stocks. The aim of our study was to provide necessary information for resource protection, rejuvenation, breeding and sustainable use of resources in many aspects. The results were as follows:1.Polyacrylamide gel electrophoresis technology was used to analyze the allozyme heterozygosity of nine F. Penicillatus stocks.Eight enzymes coded by 15 loci were clearly resolved in the nine stocks.Seven loci (Me-1,Me-2,Mdh-2,Aat-1,Sod-2,Est-1,Amy-1) were polymorphic among the nine stocks exclaimed.The results also showed that a total of 6 loci meet the Hardy-Weinberg balance (p>0.05) and 30 loci deviated from the Hardy-Weinberg balance (p<0.05) of all polymorphic loci.Except the Ningde stock,13 loci from other eight stocks showed heterozygote deficiencies.Combined with information of the observed heterozygosity and expected heterozygosity,heterozygote deficiencies may mainly due to inbreeding,natural selection,Wahland effects,dumb allele and so on. In addition,in this study a total of 23 loci showed heterozygote excess (F<0) in nine stocks,which showed that the germplasm resources of F. Penicillatus is good.2.The allozyme analysis showed that the effective number of alleles (Ae) ranged from 1.1447 to 1.2094,with an average of 1.1664;percentage of polymorphic loci ranged from 13.33% to 40.00%, with an average of 26.67%;observed heterozygosity (Ho) ranged from 0.1311 to 0.1511,with an average of 0.1380;expected heterozygosity (He) ranged from 0.0720 to 0.1023, with an average of 0.0866.Genetic distance (D) was from 0.0002 to 0.0049,genetic similarity was from 0.9951 to 0.9998. And the genetic differentiation index GST among the nine stocks was 0.0327 and gene flow (Nm) was 11.7358.The AFLP technology was used to analysis the genetic diversity and differentiation of the nine F. Penicillatus stocks. Of all the 270 individuals,508 loci were amplified by eight pairs of primers.The results showed that the effective number of alleles (Ae) ranged from 1.1956 to 1.3988, with an average of 1.2770;the percentage of polymorphic loci (P) ranged from 41.34 to 63.58, with an average of 50.88%;the shannon’s index (I) ranged from 0.1841 to 0.3425, with an average of 0.2486; Nei’s genetic diversity index (H) ranged from 0.1194 to 0.2305, with an average of 0.1643.The average genetic distance (D) was 0.0626, and the gene flow (Nm) was1.8124.Comparing the genetic diversity from our study with that of other economy shrimps and crabs,which was obtained by corresponding experimental methods,our study showed that the genetic diversity of F. Penicillatus was at a high level,and the genetic differentiation was low.3. Useing statistical software SPSS11.5 to analyze the correlation between genetic distance and corresponding geographical distance of the nine F. Penicillatus stocks using allozyme and AFLP technologies. The results are as follows: (allozyme marker part) Pearson Correlation =-0.022,Sig.(2-tailed) =0.896>0.05;(AFLP marker part)Pearson Correlations=0.146, Sig.(2-tailed)=0.394>0.05.So our study showed that there was no significant correlation between genetic distance and geographical distance between nine stocks.4. Useing magnetic-bead enrichment method to construct microsatellite library in F. penicillatus. In this experiment, 108 DNA fragments (more than 500bp) were chosen from 864 colonies. 72 microsatellite sequences were obtained by analyzing the 108 DNA fragments. 41 pairs of primers were designed by Primer Premier 5.0. Up until now, 6 pairs of primers were selected which could be used to amply special fragments.