Comparison of seven Crassostrea mitogenomes and phylogenetic analyses

摘要

Oysters are widespread and species-rich group of bivalves. The rapid growth of aquaculture and breeding programs has created a pressing need to understand the genetic variation within and among various oyster species. However, conventional taxonomic and phylogenetic studies based on morphology and geographic range information have proved problematic (e.g., Harry, 1985;Brock, 1990) because the shell morphology of oysters is phenoplastic and greatly affected by habitat (Tack et al., 1992). Also, the dispersal capability of larvae and sympatry among species can confound identifications based on geographic range (Lapègue et al., 2002). To help resolve some of the questions concerning oyster identification and phylogenetic relationships, several molecular markers have been used such as allozymes (Banks et al., 1994;Sudradjat et al., 1995), RAPD (e.g., Klinbunga et al., 2003), PCR–RFLP (Xia and Yu, 2009) and DNA sequences (e.g., Boudry et al.,2003; Yu et al., 2003; Reece et al., 2008). These studies have proved useful, to some extent, and have improved our understanding of the relationships among species and/or genera. However, inconsistent or conflicting conclusions can be drawn when different DNA sequences are used for phylogenetic analyses (e.g., Zhang et al.,2005; Reece et al., 2008).