Phylogenetic relationships and identification of juveniles of the genus Sebastes

Abstract

The genus Sebastes is speciose and most members are distributed in the northeastern Pacific Ocean (NEP). Historically, morphology has been the basis for species identification and determination of phylogenetic relationships. However, because many Sebastes species overlap in range and are similar in morphology, especially during early life stages, morphological characters are often inadequate for species identification. This study examines the potential of using restriction site variation in the mitochondrial NADH-dehydrogenase subunits -3 and -4 and 12S and 16S ribosomal RNA genes to resolve the problems in species identification and phylogenetic relationships, particularly assignments to subgenera. Of the 71 species representing 16 subgenera examined, 58 species had species-specific mtDNA markers. The identity of the remaining species could be narrowed down to small groups. Forty-nine juveniles were tested for their identity. Twenty-four specimens were identified either to species or to a small group of species; the remaining specimens were not identified because of low quality of DNA. Analysis of the coherence of current sub generic assignments revealed that only the subgenus Sebastomus was monophyletic. Some consistent groups were formed by members from different subgenera. In particular, NEP members of the subgenus Pteropodus were monophyletic with three other NEP species in two subgenera.