Study On Morphology And Genetic Diversity Of Different Populations Of Macrobrachium Nipponense

This thesis was based on Macrobrachium nipponense as research object, which sampled from the main producing area, such as the Baiyangdian in North China, Weishan Lake, Taihu Lake, Gaoyou Lake, Dianshan Lake in East China, Honghu Lake, Poyang Lake, Dongting Lake, Longgan Lake in Central China and the population of Guizhou in Southwest China. By using the method of multivariate regression analysis and microsatellite molecular marker method, we tried to analyse the morphological differences, the effect of morphological traits that contributed to the body weight and genetic diversity of M. nipponense from the point of view of morphology and molecular biology. Based on the analyse, we attempted to find out the major factors that affected the body weight. We were wishing this study could provide reference for artificial breeding of Macrobrachium nipponense, and provide fundamental basis for conservation of germplasm resources of Macrobrachium nipponense in our country. Specific research results are as follows:1. Study on the morphological differences of Macrobrachium nipponenseIn this study, multivariate analysis among eight populations of Macrobrachium nipponense was conducted by transforming the form of the morphological measurements. According to the 15 set of parameters, cluster analysis, discriminant analysis, One-Way ANO VA analysis and LSD test were conducted to analyse the male and female Macrobrachium nipponense. Cluster analysis results revealed that the structure of morphological traits had relevance with their geographical positions, divided into two geographical groups, the northern one and the southern one, both in female and male Macrobrachium nipponense. The comprehensive discrimination rate of female shrimp population was 78.5%, while the male population was 72.6%, the discriminant accuracy rate was relatively high, so we can identity the unknown shrimp population belonging to the which population according to the discriminant equation. One-Way ANOVA analysis and LSD test found that the populations of female shrimp have differences between 14 parameters, while the male shrimp have 10 parameters, which showed that the changes in the morphology of the different groups had formed, but these changes were only in geographical groups, and can not reach the degree of subspecies.2. Study Through the analysis of morphological traits on body weight of Macrobrachium nipponenseIn order to analyze the effect of morphological traits on body weight,18 in 19 measured morphological characteristics were conducted by simple correlation analysis, path analysis, determination coefficient analysis and multiple correlation analysis. Research results revealed that the morphological characteristics which beneficial to body weight of the female shrimp were more inclined to the traits related grow fatter, carapace traits (length, width, height) and the first abdominal segment traits (length, width, height), while the male shrimp were more inclined to the traits related grow longer, body length, carapace length and the first abdominal segment length. The R2 of the coefficient of determination of the reseved traits in different groups and the two two coefficient of determination were all greater than 0.85, which meaned that the core morphological characters that promoted the body weight had been found, and we also established the multiple regression equations each populations, so we hope it can provid a theoretical reference value for the artificial breeding of high-quality varieties.3. Study on the genetic diversity of Macrobrachium nipponenseWe used 7 microsatellite locis to study the genetic diversity of 10 wild populations of Macrobrachium nipponense. A total of 100 alleles were detected, and the expected heterozygosity and observed heterozygosity of each population were between 0.541-0.742 and 0.622-0.764, Shannon diversity index was between 1.524 and 1.206, which indicated that all groups had a fine genetic diversity. But the phenomenon of lack of heterozygosity appeared in Baiyangdian group, Weishan Lake group, Taihu group, Dongting Lake group and Guizhou Macrobrachium nipponense group. The government should take effective measures, such as artificial restocking of these groups, in order to ensure the sustainable development of its germplasm resources. Guizhou population and the rest of the group showed a high degree of genetic differentiation, the genetic differentiation, genetic distance and clustering results were correlated with the geographical location. The genetic distance between Guizhou population and Weishan Lake group was the biggest, and the genetic differentiation among groups was also showed moderate genetic differentiation, the two groups can be used as a breeding strategy for inter population hybridization.