Study On Morphology And Genetic Diversity In Four Wild Populations Of Oriental River Prawn(Macrobrachium Nipponense)

Macrobrachium nipponense,is an important economic value of large freshwater shrimp,widely distributed in lakes,ponds and rivers.The experimental material were randomly selected 96 individuals Baiyangdian lake(Hebei Province),Hengshui Lake(Hebei Province),Weishan Lake(Shandong Province)and Hongze Lake(Jiangsu Province).The morphological differences,the effect of morphological traits that contributed to the body weight and genetic diversity of M.nipponense were analyzed based on multivariate analysis methods of morphological measurements and microsatellite DNA markers.we attempted to find out the major factors that affected the body weight and ascertain the genetic differentiation.We were wishing this study could provide conservation of germplasm resources and fundamental basis for artificial breeding of M.nipponense in our country.Specific research results are as follows: 1.Analysis on morphological variations among four wild populations of M.nipponenseThe morphological variations among four of M.nipponense was analyzed in three multivariation analysis methods base on 16 proportional parameters.The results of cluster analysis had revealed that the morphological characters were similar between the populations of Baiyangdian Lake and Weishan Lake,and that the genetic distance of the population Hongze Lake and Hengshui Lake was farther and farther than the first two populations.The results of discriminant analysis revealed that three discriminant functions were obtained,the discrimination accuracy was 63.8%-96.3%(P1)and 62.2%-97.5%(P2),the integrated discrimination accuracy was 75.1%,which show that it is feasible to adopt stepwise discriminatory analysis to distinguish the populations.Principal component analysis revealed five principal components,contributing 17.275%?13.278%?12.979%?10.773% and 7.662%,and reaching cumulatively 61.967%.The results of the principal component analysis scatter plot are consistent with the cluster analysis.2.Effects of morphometric traits on bady weight in four wild populations of M.nipponenseBody weight and 17 morphological traits in four wild populations of M.nipponense were compared using correlation and path analysis,the results showed that there was very significant difference in the correlation coefficient between the various characters(P<0.01),and the correlation coefficients of different morphological traits of four populations were different,ranged from 0.486-0.944?0.157-0.948?0.369-0.974 and 0.155-0.968,respectively,and very significant level(P<0.01).We established the multiple regression equations of each population by stepwise regression analysis method and partial regression coefficient significance test.Total length and body length showed a largest direct impact on body weight of Baiyangdian group;second pereiopod length showed a largest direct impact on body weight of Hengshui Lake;total length showed a largest direct impact on body weight of Weishan Lake group;carapace length and abdomen height showed a largest direct impact on body weight of Hongze Lake.These results provide a theoretical basis for selective breeding of M.nipponense.3.Microsatellite analysis of genetic diversity in four wild populations of M.nipponenseGenetic diversity and differentiation of different wild population of oriental river prawn(M.nipponense)in Baiyangdian Lake,Hengshui Lake,Weishan Lake and Hongze Lake,was investigated using 22 microsatellite DNA loci.The data showed that all the 22 loci were highly polymorphic.An exact P-value test indicated that most loci significantly deviated from Hardy-Weinberg in the Baiyangdian Lake,Hengshui Lake and Hongze Lake populations with the number of 9 loci,respectively;the deviations of Hardy-Weinberg were also detected in Weishan Lake populations with the number of 6 loci.All of the four wild populations showed high genetic diversities,and the genetic diversity in Weishan populations was relatively higher than three the others three populations.The Fst and AMOVA analysis suggested that there was a moderate degree of genetic divergence among the four populations(0.0463< Fst <0.1012).UPGMA clustering tree based on Nei's genetic distance demonstrated that the populations of adjacent geographical position clustered together.