Sequencing cytochrome oxidase subunit I of mitochondrial DNA and the taxonomic status of apple snails.
The fragments of mitochondrial cytochrome oxidase subunit I (CO I) gene were amplified from 29 Apple Snails in 6 different locations, then sequenced and analyzed. Compared with the corresponding CO I gene sequences of Pomacea canaliculata, P. insularum, P. diffusa, P. haustrum, P. paludosa, P. camena and Pila conica in the ampullariids published in GenBank, the taxonomic status of introduced Apple Snails in six regions of China was examined. The results showed that the length of CO I gene sequence was 619 bp, including 99 variable sites and 80 parsimony sites. The average contents of A, T, C and G were 23.6%, 39.1%, 16.6% and 20.7%, respectively. Total 13 different haplotypes of apple snails were found in 6 different locations. There were 3 haplotypes in Guangzhou, Qinzhou and Jian, and two haplotypes in Maoming, Xiamen and Yaan. In addition, 3 locations of Guangzhou, Xiamen and Qinzhou all existed a uniform haplotype. Molecular analyses showed that the genetic distances ranged from 0.114 to 0.191 between apple snails in six locations in China and Pomacea diffusa, P. haustrum, P. paludosa, P. camena, 0.011 to 0.063 between P. insularum and Haplotype 4, 5, 6, 9, 13, and 0 to 0.074 between P. canaliculata and other eight haplotypes. Phylogenetic analysis based on the mitochondrial CO I gene segregated them into seven major clades including 6 species of the genus Pomacea and one of the genus Pila. Haplotype 1, 2, 3, 7, 8, 10, 11, 12 and Pomacea canaliculata formed a clade that was sister to the P. insularum clade including Haplotype 4, 5, 6, 9, 13. Sequence analysis, genetic distances and Phylogenetic trees suggested that there were two species of non-native apple snails in China continent including P. canaliculata and P. insularum, and this two species had mixed with each other in the course of pervasion. This study will provide a scientific basis for developing resources investigation, control and management of apple snails in the future.