Population Genetic Analysis of Rainbow Clam Moerella iridescens by Using rDNA

Abstract

To assess the genetic background of the germplasm resource of rainbow clam Moerella iridescens along China coasts, population genetic structure and genetic diversity of rainbow clam from five geographical populations in the Yellow Sea and the East China Sea (Lianyungang, Chongming, Cixi, Zhoushan, and Ningde) were analyzed based on rDNA (ITS1-5.8S-ITS2) sequences. Forty-Seven rDNA haplotypes were identified among 109 rainbow clam individuals of the five populations. Gen4 and Gen21 were the dominant haplotypes, accounting for 49.5% of rDNA whole gene sequences, and shared by the five populations. Six to eight exclusive haplotypes were found in each population. The average haplotype diversity index (HD) of the five populations was 0.8733. The genetic distance among populations ranged from 0.002 to 0.004, and haplotypes from the same population were not clustered in a single clade. Molecular variance analysis (AMOVA) demonstrated that the main genetic differentiation mainly occurred within population, and the genetic differentiation coefficient (FST) among five populations was between-0.02836 and 0.01896, which meant that no genetic differentiation among populations occurred. Overall, the five geographical populations showed a high genetic diversity, but no evident genetic structure or genetic differentiation. Qinhuangdao (Hebei), Yellow River Delta (Shandong), Lianyungang (Jiangsu), Chongming Island (Shanghai), and Haimen (Guangdong), and etc. The different climate of each sea area and the diversity of ecological environment may lead to genetic differentiation among the geographical populations of M. iridescens, which is closely related to its adaptability, reproductive capacity and evolutionary potential (Sokal et al., 1989). For the recent more than a decade, over-exploitation and shrimp farming in the inning beach have led to a fragmented natural ecological environment of M. iridescens in habitat, degradation of germplasm resources, and severely declining resources quantity of M. iridescens (Li et al., 2009; You and Wang, 1990a, 1991b). So it is necessary to effectively assess genetic resources so as to take rational conservation strategies. The richer the genetic diversity of a species, the stronger its adaptability to environmental changes, and it is easy to expand its distribution range (Su et al., 2007). Therefore, assessing population genetic diversity is of great scientific and practical significance in protecting and managing the germplasm resources of M. iridescens. A few of reports are available regarding the germplasm resources and molecular biology of M. iridescens. In the analysis of geographical population morphological variation and micro chemical composition in the population, the heavy metal pollution characteristics of M. iridescens in Hangzhou Bay and Haizhou Bay were quite different, which also indicated that the habitat of M. iridescens was greatly affected by human beings (Li et al., 2010a; Dong et al., 2012). ISSR primers for germplasm evaluation of M. iridescens was established, the geneti...

SSR Marker-Based Genetic Resource Assessment of the Rainbow Clam Moerella iridescens Along the Coasts of China: Implications for Strategy of Conservation Management

“…Total DNA was extracted with the sodium dodecyl sulphate (SDS) phenol-chloroform method and according to the detailed protocol for the DNA extraction as previously described by Li et al (2020). The PCR system and program in this study was done as previously described by Zhang et al (2019).…”