Characteristics and phylogenetic analysis of mitochondrial genome in the gobies

Abstract

The vast number of species, small size and high variation of morphology make the morphological identification and classification of gobies very difficult. In this study, the complete mitochondrial genome (mitogenome) of 26 species of gobies was analyzed, aiming at accumulating the molecular information on the identification, classification and molecular evolution of gobies. The results showed that the gene composition and arrangement of mitogenome of gobies are similar to most vertebrates. Due to various degrees of repetitive sequences in the control region, the mitogenome of 26 gobies exhibits a great variation in length. The A+T content of the mitogenome is greater than 50% and the lowest frequency is for G among the four bases. Thirty-seven coding gene sequences were used to calculate the average Kimura 2-parameter genetic distance of 26 species of gobies. Acanthogobius hasta and A. ommaturus, Glossogobius olivaceus and G circumspectus were synonyms, respectively. By comparing the control region sequences of 26 gobies, the terminal associated sequences, central conserved sequence block and conserved sequence block were identified, respectively. Thirty-six coding gene sequences of 26 gobies were used to construct the phylogenetic tree and the results were different from the traditional morphological classification. The five subfamilies of Gobiidae were obviously evolved: Amblyopinae, Oxudercinae and Sicydiinae were clustered into a group and then formed a sister group with Gobionellinae; the fishes of Gobiinae had distant relationship with the four subfamilies and formed a group alone. Molecular clock analysis estimated that gobies probably originated in the late Eocene to Oligocene time and further evolved into modern characteristic gobies in the Miocene.