Studies On The Molecular Phylogeny And Taxonomy Of Common Oysters In China Seas

Oyster is distributed widely in the world. It is one of the most important and best-knownspecies that cultured in China and other countries. Oyster classification remains problematic, andtaxonomic status for many species has not been satisfactorily resolved. This problem is mostpronounced in China, where diverse groups of oysters occur. Difficulties in oyster classificationhave partly rooted in the lack of well-defined morphological characters. Shell morphology, themain character used in oyster characterization, is known to be plastic and subject toenvironmental variation. The classification of some oysters has been a subject of confusion anddebate in China, clarifying the taxonomic status of oysters needs to be done urgently in Chinawith different methods. In this study, we collected and analyzed oysters from many locationsalong China's coast using both morphological characters and DNA sequence data frommitochondrial 16S rRNA and cytochrome oxidase I, and the nuclear 28S rRNA genes, thensubjected to Phylogenetic analysis of DNA sequences obtained in this study and existingsequences of reference species. The jinjiang oyster (Crassosstrea rivularis Gould 1861) is one of the most important andbest-known oysters in China. It has been cultured in China for centuries. Based on the color of itsflesh, two forms of C. rivularis are widely recognized and referred to as the "white meat" and"red meat". The classification of white and red forms of this species has been a subject ofconfusion and debate in China. To clarify the taxonomic status of red and white forms of C.rivularis, we collected and analyzed oysters from five locations along China's coast using bothmorphological characters and DNA sequence data from mitochondrial 16S rRNA andcytochrome oxidase I, and the nuclear 28S rRNA genes. Oysters were classified as white or red a英文摘要forms according to their morphological characteristics and then subjected to DNA sequencing.Both morphological and DNA sequence data suggested that the red and white oysters are twoseparate species. Phylogenetic analysis of DNA sequences obtained in this study and existingsequences of reference species showed that the white oyster is the same species as a newlydescribed species from Hong Kong, C. hongkongensis Lam and Morton 2003. The red oyster isthe same species as C. ariakensis Fujita 1913. Although the name C. rivularis has seniority overC. hongkongensis and C. ariakensis, the original description of Ostrea rivularis by Gould 1861does not fit shell characteristics of either the red or the white oysters. We propose that the nameof C. rivularis Gould 1861 should be suspended, the white oyster should take the name C.hongkongensis, and the red oyster should take the name C. ariakensis. The other subject of confusion and debate is about the taxonomic status of oysters distributedin North China coasts. The shell morphology of these oysters varied largely at differentenvironments. Several names were used to describe these oysters and there are many confusionand disagreements about it. To clarify the taxonomic status of these oysters, we collected andanalyzed oysters from nine locations along North China's coast using both morphologicalcharacters and DNA sequence data from mitochondrial 16S rRNA and cytochrome oxidase I,and the nuclear 28S rRNA genes. Both morphological and DNA sequence data suggest that thereare two species of oysters in North China sea. Phylogenetic analysis of DNA sequences obtainedin this study and existing sequences of reference species showed that the oyster collected fromWeifang is the same species as C. ariakensis Wakiya,1913, oysters in other sites are the samespecies as C.gigas. We propose that the old name of S.cuccullata and C.plicatula should besuspended for this oyster. Another subject of confusion and debate is about the taxonomic status of oysters distributed inSouth China coasts. Currently, it was considered t...