Study On Comparative Morphology Of Typical Stocks Of Sinonovacula Constricta Along The Coast Of China And Genetic Structure Of Zhejiang And Fujian

Sinonovacula constricta is one of four major aquacultural clams, which belongs to a benthic razor clam species living in the lower-to-mid intertidal zones. Razor clams were originally cultivated about several hundred years ago in Zhejiang and Fujian Provinces of China, and now cultivated along the coast of China. With the gradually expanded extent of culture, a large number of wild juvenile clams were introduced into other coastal culture districts from Fujian Province. It is necessary to research in genetic resources of razor clam. In this paper, 7 geographical stocks of Sinonovacula constricta along the coast of China, 9 stocks from Yueqing Bay in Zhejiang Province and 9 stocks from Sansha Bay in Fujian Province were analyzed by multivariate morphometrics analysis method and SSR of genetic diversity to provide important theoretical basis for identifying geographical stocks, conservation and utilization of aquatic genetic resources of Sinonovacula constricta in Zhejiang and Fujian Province. Our studies are as follows:1. Morphological Variations and Discriminant Analysis of 7 Stocks of Sinonovacula constricta along the Coast of ChinaThe multivariate morphometrics analysis method was used to study 12 morphological characters of 7 geographical stocks of Sinonovacula constricta from Zhuang-he, Han-gu, Hai-yang, Yan-cheng, Chong-ming, Ning-bo and Zhang-zhou, along the coast of China. The results of cluster analysis revealed that Han-gu and Hai-yang stocks were firstly clustered with Zhuang-he, then with Chong-ming and Yan-cheng finally clustered with Ning-bo and Zhang-zhou stocks. In the principal component analysis, three principal components were constructed, the contributory ratios of the three principal components were 36.28%, 22.23% and 12.72%, and the cumulative contributory ratio was 71.231%, respectively. The result of discriminant analysis revealed that there were significant differences among the 7 stocks (P<0.01). The discriminant functions of seven stocks were established, and the accuracy was 66.67%-86.67% (P1) and 68.96%-100% (P2). The total discriminant accuracy was 77.93%.2. Analysis on genetic structure of Sinonovacula constricta stocks from Yueqing Bay in Zhejiang Province9 stocks of Sinonovacula constricta: Weng-yang, Yue-cheng, Nan-yue, Nan-tang, Qing-jiang, Hu-wu, Wu-gen, Hai-shan, Lu-pu were sampled from Yueqing Bay in Zhejiang Province. Genetic structure of Sinonovacula constricta stocks were analysed by 8 pairs of microsatellite primers. The results showed that: The average effective allele numbers (Ne) were from 8.146 to 10.457, and the values of expected heterozygosity (He) were from 0.872 to 0.909. There were higher genetic diversity and no obvious differentiations among 9 stocks. Mutation-drift equilibrium analysis shows that 9 stocks of Sinonovacula constricta in Yueqing Bay, with heterozygote excesses, were significantly deviations from mutation-drift equilibrium. It might be indicated that the stocks in all of Yueqing Bay had suffered bottleneck effects in the past as well as the recent stock decline. AMOVA showed that only 0.63% was due to among stock variance. There was mild level of differentiation among 9 stocks (FST<0.05). The UPGMA phylogenetic trees based on DA genetic distance suggested that Nan-yue was firstly clustered with Lu-pu, then with Qing-jiang, Hu-wu, Yue-cheng, Nan-tang, Hai-shan, and finally with Weng-yang and Wu-gen.3. Analysis on genetic structure of Sinonovacula constricta stocks from Sansha Bay in Fujian Province 9 stocks of Sinonovacula constricta: Zhang-wan, Mei-tian, San-dou, Yu-jiang, Bai-zhao, Xi-wei, Chang-chun, Sha-jiang, Xia-tang were sampled from Yueqing Bay in Fujian Province. The results showed that: The average effective allele numbers (Ne) were from 7.457 to 9.947, and the values of expected heterozygosity (He) were from 0.846 to 0.894. There were higher genetic diversity and no obvious differentiations among 9 stocks. 9 stocks of Sinonovacula constricta in Sansha Bay were significantly deviations from mutation-drift equilibrium with heterozygote excesses. It might be indicated that the stocks in all of Sansha Bay had suffered bottleneck effects in the past as well as the recent stock decline. AMOVA showed that only 2.38% was due to among stock variance. There was some degree differentiation among 9 stocks. The UPGMA phylogenetic trees based on DA genetic distance suggested that San-dou was firstly clustered with Sha-jiang, then with Xia-tang, Chang-chun, Mei-tian, Yu-jiang, Xi-wei, Zhang-wan, and finally with Bai-zhao.