DNA Barcoding And Molecular Phylogeny Of Caenogastropoda

Caenogastropods comprise about60%of living gastropod species and include alarge number of ecologically and commercially important marine families. Therelationships between the families and superfamilies remain largely unresolvedphylogenetically. The living of Caenogastropods is threatened because of the pollutionand global environment problem in the recent years. As the basic of species diversityresearch and protection, DNA-based approaches for taxon diagnosis have become thefocus of much attention in recent years. In our study, we assessed the utility of DNAbarcoding based on COI genes, and then analysed the phylogenetic relationships ofCaenogastropods using molecular markers.DNA barcoding provides an efficient method for species-level identifications. Inthis study, we have amplified partial sequences of mitochondrial cytochrome coxidase I (COI) gene from110specimens of45species of Caenogastropoda collectedfrom the coast along China to evaluate whether DNA barcodes can distinguish thesespecies accurately. The average Kimura two parameter (K2P) distances within species,genera and families were0.44%,13.96%, and22.27%, respectively. These resultsproved that the species of Caenogastropoda can be efficiently and accuratelyidentified by DNA barcoding based on the COI gene.The16S rRNA genes form26species of Caenogastropoda were sequenced to inferthe phylogenetic relationships, the sequences gathered from Genbank and the COIgenes were included. Both the Neighbour-joining tree and the Bayesian tree showed aclear discrimination of all the species in our study with highly supported clades. COIgene analyses did not well resolve the basal dichotomy between deep clades, whilethe result of16S rRNA analyses was better, all the species of six superfamiliesclustered under the same nodes. The results indicate that the phylogeneticrelationships of Caenogastropoda constructed by COI and16SrRNA genes are almostconsistent with traditional morphological analyses.