Molecular Phylogeny Of Bivalves Inferred From RDNA And Genetic Diversity Of Pinctada Martensi

Bivalves constitute a dominant and divers group of marine animals in our country. Most of them are of major commercial important species, and studies on their genetic diversity are necessary for the sustainable exploitation and conservation of these bioresources. The objective of the present study is to explore the feasibility of using the ribosomal DNA as a molecular marker for studying the interspecific phylogenetic relationship and intraspecific genetic variations among bivalves. The 18S-ITS1 sequences of 11 species at differing taxonomic levels were determined. The sequences were found to exhibit a high degree of length polymorphism among different species, ranging from 558 bp (Chlamys farreri) to 784 bp in (Ostrea rivulahs), mainly resulting from the variation of ITS1. The percent divergence of sequences ranged from 3.8% to 60.4%. The NJ (neighbor-joining) tree inferred from 18S fragment of 14 species agree with the previous based on morphologies and chemical analysis well. The sequence was found to vary among 4 geographical sites of Pinctada martensi, ranging from 0.6% to 1.9%. The variations involved substitutions, transversion as well as insertions and deletions among them in P.martensi. All these results show that ITS1 is highly divergent among different species of bivalves and could be used in classification and distinguishing closely related species, and also could be used for molecular systematic studies at relative species, subspecies and population levels.Pinctata martensi is one of the most important aquacultural seashells in the southeast of China. Wild individuals were collected from Sanya (Hainan province), Beihai (Guangxi province) and Daya Bay (Guangdong province) randomly, then mated and cultured in the same condition. In order to get a deep understanding of it and improve efficiency of breeding by marker-assisted selection, we using 27 primers tested different filial populations by RAPDtechnique. The results showed that the diversity Shannon index of filial population mated from inter-populations was higher than filial populations mated from inner-populations. Then we analyzed the feasibility of breeding from two different areas.