Study On Morphology And Genetics Of Eriocheir Sinensis

Eriocheir sinensis,which belongs to family Decapoda. order Grapsidae,is an economically and culture species. E. sinensis is widely distributes at China. Because of long-term over exploitation, the wild resource of Chinese mitten crab is deficient day by day. Currently, the artificial breeding and enhancement and releasing have leaded to mingle of different populations which was inhabitant at different drainages. In this study, we systematacially analyzed E. sinensis population genetic diverstiy and genetic structure by using morphological analysis and mtDNA melocular genetic analysis, and evoluate the effectiveness of enhancement use microsatellite maker and mtDNA melocular maker. Finally, mitochondrial COI,D-loop and Cyt b fragment were used for analysing the differention of four kinds of mitten crab. (1) Morphological analysis of Eriocheir sinensis populationEighteen measurement characteristics of 123 individuals from 4 populations (Dongying,Panjing,Nanjing,Suzhou) were measured by conventional morphological and the data was analyzed by using oneway-ANOVA analysis, discriminant analysis, principal componnet analysis and cluster analysis. One way-ANOVA analysis showed that 6 indices were insignificantly different between Nanjing population and Suzhou population.while 5 indices were significantly different between Suzhou population and Panjin populaiton:the results of discriminant analysis showed that the correct classification ratio distributed from 71.4%～84.2%,and the average classification ratio was 77.7%. scatter diagram of discriminant analysis showed that samples of four popilation chaotic distributed:the results of principal component analysis showed that the first 6 principal components explained 82.1% of morphological difference, the differention was mainly focus on carapace:the result of cluster analysis showed that population Panjin and Nanjing were pooled in one group, then pooled with other populations. The results of multivariate statistical analysis methods showed that there was no significant Morphological differentiation existed among four geography populations.(2) Studies on genetic diversity of Chinese mitten crab Eriocheir sinensis based on mitochondrial DNA control regionTo investigate the genetic structure and diversity of Chinese mitten crab Eriocheir sinensis. the 458 bp hypervariable fragments of mitochondrial DNA control region were sequenced and analyzed. In the present study.114 individuals were collected from Tumenjiang. Dandong. Panjing. Kenli and Nanjing. The fragments revealed 58 polymorphic sites, which defined 54 haplotypes. The results revealed that the haplotype diversity indices of five populations ranged from 0.848±0.070 to 0.952 ±0.032, while the values of nucleotide diversity ranged from 0.010±.006 to 0.019± 0.010. The results of present study showed that the genetic diversity of Chinese mitten crab were at high level. There were some genetic differentiations among those five wild populations. The genetic differentiation between Dandong population and Nanjing population was the largest (Fst=0.13.P<0.05). while the genetic differentiation between Panjin population and Tumenjiang population was the least (Fst=-0.04,P>0.05). The exact test of population differentiation (non-differentiation exact P values) following sequential Boferroni correction showed that no significant differences existed between Kenli population and Nanjing population, which supported null hypothesis. Significant genealogical structure was also not detected corresponding to the sampling sites based on the MST and NJ phylogeny analyses.(3) Comparative analysis of genetic variation in artificial releasing and wild populations of Chines mitten crab Eriocheir sinensis based on mitochondrial DNA control regionTo investigate the genetic variation and diversity of Chinese mitten crab Eriocheir sinensis among one artificial releasing population and three wild populations, the 455 bp hypervariable fragments of mitochondrial DNA control region were sequenced and analyzed. The results revealed that the gene diversity indices of artificial releasing population was 0.950±0.021. the gene diversity indices of wild populations were 0.018 ± 0.009～0.023±.012,which were the same as the artificial releasing population, while the values of nucleotide diversity for both releasing and wild populations were at high level. Among the 50 haplotypes defined, only 9 of them were shared by wild population and artificial releasing population. The result of pairwise Fst and AMOVA indicated no significant genetic differentiation existed among wild populations and artificial releasing populations (P>0.05). Significant genealogical structure was also not detected corresponding to the releasing and wild populations based on the MST and NJ analyses.(4) Effect of restocking enhancement of Chinese mitten crab Eriocheir sinensis based on molecular markersChinese mitten crab is an economic species in the north of Chinese aquaculture, whose wild resources is scarce. Currently, hatchery-reared juvenile E.sinensis are released into natural waters to supplement the wild population. However the effectiveness of these enhancement efforts has not be evaluated to date. To address this, we collected 40 juveniles when they cultivated in the hatchery and 72 recaptured individuals. Microsatellite DNA loci together with nucleotide sequences of the mitochondrial DNA (mtDNA) control region were used as genetic tags, and we compared the properties of the two molecular markers in tracking the released mitten crab. For mitochondrial DNA maker, the analysis showed that 6 mtDNA haplotypes were observed in 22 of the 72 E.sinensis recaptured individuals, which were also shared by E.sinensis juveniles. For microsatellite maker,67 of the 72 are not the survivors of released E.sinensis. Tracking the released Chinese mitten crab analysis showed 3 of the 72 E.sinensis recaptured individuals are the survivors of released E.sinensis. Based on the method of combing the two molecular markers, accounted for 4.17% of the recaptured individuals. As expected, microsatellite maker are more efficient than mitochondrial DNA maker, which can be dominant marker in case of dealing with massive samples.(5) Comparative Analysis of mtDNA Gene among three kings of mitten crabTo elucidate the phylogeny and taxonomy of Eriocheir,mitochondrial COI, D-loop and Cyt b fragment were used for the combined analysis. E. sinensis. E. hepuensis, E.japonica. and E. japonica-ok form four separate monophyletic groups in the NJ, MP and BI trees. The average intraspecific genetic distance within E. sinensis. E. hepuensis, E. japonica. and E. japonica-ok was lower than their interspecific genetic distance significantly. The mean pairwise Fst value obtained from E. japonica, and E. japonica-ok comparisons was no significant difference with other species. Results of the AMOVA revealed that 87.80% of the total molecular variance can be attributed to the significant differences among species. The study showed significant genetic difference among E. sinensis. E. hepuensis. E. japonica. and E. japonica-ok and E. japonica-ok should be ragard as a valid species.