Phylogenetic relationships of 12 Penaeoidea shrimp species deduced from mitochondrial DNA sequences

DNA sequences of an 847 bp fragment of mitochondrial cytochrome oxidase subunit I (COI) gene and a 514 bp fragment of 16s rRNA gene were determined to examine the phylogenetic relationships of 12 Penaeoidea shrimp species (Penaeus chinensis, Penaeus japonicus, Penaeus penicillatus, Penaeus vannamei, Penaeus canaliculatus, Trachypenaeus curvirostris, Metapenaeus affinis, Metapenaeus ensis, Metapenaeopsis barbata, Parapenaeus fissuroides, Parapenaeopsis hardiwickii, Solenocera crassicornis). Both fragments of the swimming crab Portunus trituberculaus chosen as the outgroup were also sequenced. Intraspecific sequence divergence of 0.24-1.2% in the COI gene was found in 5 species, while no intraspecific variation was observed in the 16s rRNA gene. Three phylogenetic trees based on the 1361 bp combined sequences of COI and 16s rRNA were concordant in indicating the following suggestions: (1) phylogenetic relationship of the 11 Penaeidae species based on our result support the opinion of Burkenroad (Burkenroad, M.D. (1983). Crustacean Issues 3: 279-290) on the basis of morphological features; (2) it seems more reasonable to class Solenocera crassicorni in the family Penaeidae; (3) the fragment of the COI gene chosen here appears to be a good marker for speciation studies and population analysis in Crustaceans, while the 16s rRNA gene fragment here seems suitable for examining phylogenetic relationships at the species or genus levels in Crustaceans. Our time estimates suggest that Penaeus and Metapenaeus might have separated about 6.38x10(6)-7.98x10(6) years BP in the post-Miocene, and the species separation within Metapenaeus and Penaeus might occur 0.08x10(6)-0.4x10(6) years BP in the late Pleistocene.