Differences in the 16SrRNA and cytochrome c oxidase subunit I genes in the mullets Mugil cephalus and Mugil curema, and snooks Centropomus viridis and Centropomus robalito

The mitochondrial genes coding for 16SrRNA and cytochrome c oxidase subunit I (COI) in four commercially important fish from the Gulf of California were studied. These fish species were the striped mullet Mugil cephalus and white mullet Mugil curema, and the white snook Centropomus viridis and yellowfin snook Centropomus robalito. Fragments of the 16SrRNA and COI genes were obtained by PCR amplification. Restriction digest of the amplicons for both genes revealed different banding patterns among the four species. The genetic distances based on the 16SrRNA gene sequence were smaller than for COI for both groups of species. Phylogenetic inference for both genes showed monophyly of the four species in two separate groups, one comprising the mullets and the other the snooks. Monophyly of the groups was observed despite the polytomies with the rest of the species included in the bootstrap analysis of maximum parsimony and maximum likelihood analyses.