DNA Barcoding And Molecular Phylogeney Of Partial Species Of Bellamya (Gastropoda:Viviparidae)

Many species of Bellamya (Gastropoda:Viviparidae) is widely distributed in china. The most widely distributed are Bellamya quadrata, Bellamya purificata and Bellmaya aeruginosa. We performed our research at the Bellamya group in order to verify the mitochondrial COI gene and16SrRNA as DNA barcodes and for phylogenetic studies. The main work and conclusion of the present study were as the following:The first section:We performed our research at the Bellamya group in order to verify the mitochondrial COI gene and16SrRNA as DNA barcodes for species identification. The main basis are genetic distance and the phylogentic relationship. Genetic distance was caculated in MEGA4.0software, and phylogenetic trees were constructed with PAUP, PhyML and MrBayes software. The results showed that genetic distance between species is higher than that within species. And all individuals of each species formed a clade in the phylogenetic trees. However, genetic distance does not reached that Hebert proposed "standard sequence threshold" that the average genetic distance between species should be10times higher than that within species. Because the biological is not a commodity, DNA barcodes can not be the same as the product. In determining species boundaries, it is also very important to consider the special environment of the geographical distribution and groups. In this study, we could conclude that COI gene was a valid marker for DNA barcoding of Bellamya taxa, and16SrRNA gene could also be a substitute gene as DNA barcodes.The second section:To assess the phylogenetic relationship between Bellamya species, we combined the mitochondrial COI gene sequences and16SrRNA gene sequences for phylogenetic construction of the Bellamya species. The phylogenetic tree revealed three groups. Bellamya aeruginosa and Bellamya purificata formed sister groups. And all individuals of each species formed a clade in the phylogenetic trees. However, the results does not support that Bellamya dispiralis exist as an effective species, we suggested that it should be incorporated into the subspecies of Bellamya aeruginosa.