| Mitten crab,Eriocheir is one of the important economic crustaceans in East Asia,especially the coastlines and rivers of China,Korea and Japan.At present,the mitten crabs in China are widely distributed from Liaohe,Huanghe,Yangtze,Oujiang,Minjiang and Nanliujiang River basins.The germplasm resources of the wild mitten crab populations from Liaohe,Huanghe and Yangtze River basins have been developed and applied to a certain extent,the aquaculture industry is huge and the economic benefits are remarkable,but they also face a series of problems,such as inbreeding,germplasm hybridization and aquaculture performance degradation.Up to now,the genetic information of Eriocheir s.s.populations from Oujiang,Minjiang and Nanliujiang River basins has not been systematically evaluated and developed,it is not conducive to genetic diversity assessment,germplasm conservation and exploitation of mitten crab.The phylogenetic relationship and taxonomic status of Eriocheir sinensis,Eriocheir hepuensis and Eriocheir japonica were still controversial,and its genetic relationship and taxonomic status are conducive to the protection of germplasm resources of Eriocheir.Therefore,based on the molecular markers of mitochondrial genome and fatty acid biomarkers,the genetic diversity and genetic structure of Eriocheir s.s.populations from the six major rivers in China were evaluated comprehensively.At the same time,the phylogenetic relationship and taxonomic status of Eriocheir s.s.were analyzed based on mitochondrial genome,so as to provide basic materials for the identification of Eriocheir germplasm,the seeding selection,and the rational development and protection of resources.Mainly included the following contents:1 Genetic diversity and genetic structure of mitten crab(Eriocheir sensu stricto)populations from six major river basins by mitochondrial DNA COI gene sequenceThis study was designed to evaluate the genetic diversity and genetic structure of Eriocheir s.s.populations from Liaohe,Huanghe,Yangtze,Oujiang,Minjiang and Nanliujiang River basins based on mitochondrial DNA cytochrome oxidase subunit I(COI).The results showed that there were 71 variable sites and 54 parsimony informative sites in the 647 bp of sequenced mt DNA COI from 203 samples.52 haplotypes were identified,of which 10 haplotypes were common to the six populations.The six Eriocheir s.s.populations showed a trend of high haplotype diversity and low nucleotide diversity.AMOVA showed a significant difference in the level of genetic differentiation between the six populations.The maximum likelihood tree and haplotype network diagrams showed that the three Eriocheir s.s.populations from Liaohe,Huanghe and Yangtze River basins have common ancestral haplotypes,which does not intersect with the mitten crab population from Nanliujiang River basin,and Minjiang and the Oujiang River Eriocheir s.s.populations ware evenly distributed between the two branches.The results of UPGMA indicated that the geographical distance has a certain relationship with the genetic distance values of the six populations.According to the neutral test and mismatch analysis,they are concluded that the four Eriocheir s.s.populations from Liaohe,huanghe,Yangtze and Nanliu River basins have experienced population expansion or a short evolutionary history after the bottleneck effect.Based on the mitochondrial COI gene sequence,it is further speculated that the mitten crab population from Nanliujiang River basin was likely not the same species as the mitten crab populations from Liaohe,Huanghe and Yangtze River basins.In conclusion,these results have great significance for the evaluation and exploitation of germplasm resources of Eriocheir s.s.2 The population inheritance of six mitten crab populations(Eriocheir sensu stricto)in coastal china based on phospholipid fatty acids biomarkersThe fatty acid composition of aquatic animal muscles can be used to evaluate their population inheritance.In this study,the fatty acid compositions of the six Eriocheir s.s.population muscles were measured and compared in phospholipid fatty acids biomarkers.The genetic diversity and phylogenetic relationship were analyzed among the six Eriocheir s.s.populations.The results show as follows: 1.All the six Eriocheir s.s.populations contained 26 types of fatty acids among which the total volume of seven main fatty acids C20:5n3,C18:1n9,C22:6n3,C16:0,C20:4n6,C18:2n6,and C18:0 was over 74%;2.There were eight fatty acid indices with high contribution to the discrimination of the six Eriocheir s.s.populations,including C17:0,C18:0,C20:0,C22:1n9,C18:3n3,C18:3n6,C20:2n6,and C22:5n3.Relevant discrimination equations were established for each Eriocheir s.s.population,the synthetic discriminant accuracy was 98.33%;3.The results of cluster analysis show that the Euclidean distance between OJ and MJ populations were the closest,and the distance between HH and YZ populations were relatively larger than those of OJ and MJ populations,and the Euclidean distance of HP population was the farthest compared with the other five populations;4.Among the six Eriocheir s.s.populations,the variable coefficients of fatty acid content ranged 2.99% ~ 30.00%,and the genetic diversity indexes varied from 3.2732 to 3.3204.Overall,the genetic diversity indices of the six populations were quite high based on phospholipid fatty acids biomarkers.Fatty acids were effective to identify the six Eriocheir s.s.populations.The phylogenetic relationship of the other five populations were the farthest from HP population.The results of this study provide basic information for the evaluation,development and utilization of germplasm resources of Eriocheir s.s.3Analysis of the population inheritance and phylogenetic relationships of Eriocheir sinensis,E.hepuensis,E.japonica,and the mitten crab from Minjiang river basin based on complete mitochondrial genomesThe mitten crab Eriocheir sensu stricto was currently one of the most important economic crustaceans animal of East Asian Region,but the phylogenetic relationship and taxonomic status of Eriocheir sinensis,Eriocheir hepuensis and Eriocheir japonica were still controversial,and the affiliation of the mitten crab population from Minjiang River basin is also uncertain.This study analyzed the taxonomic status,genetic relationship,and the affiliation among the four populations of Eriocheir s.s.based on the mitochondrial genomes.The results showed that the mitochondrial genomes of the four Eriocheir s.s.were composed of 13 protein coding genes,2 r RNA genes,22 t RNA genes and 1 control region,and the gene order of the complete mitochondrial genomes of the four Eriocheir s.s.populations were the same.The distribution of mutation locis showed a clear trend.E.sinensis,E.hepuensis and E.japonica have themselves unique mutation locis,and the variation locis of E.sinensis and E.hepuensis populations existed in different individuals of the mitten crab population from Minjiang River basin.Based on the complete mitochondrial genomes and 13 protein coding genes,Bayesian phylogenetic analysis tree and the maximum likelihood trees were constructed,respectively.The results showed that E.sinensis,E.hepuensis and E.japonica were neatly divided into three branches,and the individuals of the mitten crab population from Minjiang River basin were evenly distributed between the branches of E.sinensis and E.hepuensis populations.In summary,based on the molecular marker analysis of mitochondrial genome,this study speculated that E.sinensis,E.hepuensis and E.japonica populations are likely to be the three species with the same taxonomic status in the genus Eriocheir,and mitochondrial genome sequences of the mitten crab population from Minjiang River basin have intersections with those of E.sinensis and E.hepuensis populations.Therefore,this study speculated that the mitten crab population from Minjiang River basin is likely to be a mixed population between E.sinensis and E.hepuensis populations. |
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