Characteristics And Phylogenetic Analysis Of Mitochondrial Genome In The Labridae

The Labridae fish, belongs to Perciformes, Labroidei, which is widely inhabited in tropical and subtropical waters, and it mostly feed on shellfish. Wrasse fish usually has high ornamental value. There were over 161 species in 37 genera in China, Size ranging from a few centimeters to several meters. Concealment of wrasse species identification has brought great distress diversity and body characteristics of the body. As a huge biological group, the morphological diversity makes traditional morphological identification of labridae very difficult, and it is also very difficult to clarify the evolution status and origin of the species through morphological and statistical. In this study, we firstly determined the complete mitochondrial genome of Bodianus oxycephalus and analyzed sequence features for coding and non-conding region. Meanwhile, in order to accumulate molecular data for the study of the family Labridae, we used 17 complete mitochondrial genome sequences by Bayesian method to construct the phylogenetic tree and estimate the origin time for Labridae.The main studies are as follows:(1) This paper determined the complete mitochondrial genome of Bodianus oxycephalus, and analyzed sequence features for coding and non-conding region. All of 22 tRNA genes can fold into a typical cloverleaf structure except for tRNA-Ser(AGY), which lacks a dihydrouridine arm. As in most vertebrates, two non-coding regions are found in B. oxycephalus mitogenome, an OL within the WANCY region including five tRNA genes, which can fold into a stemloop secondary structure with the conserved motif 5'-GCCGG-3'. We identified the central and conserved sequence(CSB-1, CSB-2, CSB-3) domains in the control region.(2) Combined with other Labrida mitochondrial genome sequence, which obtained from GenBank database, we analyzed the 16 SrRNA, ND1, COI, Cytb and the control region respectively. The result showed that the A+T content is higher than G+C content, whith a slight anti G bias.(3) We used 17 complete mitochondrial genome sequences by Maximum likelihood and Bayesian method to construct the phylogenetic tree. The result showed that Bodianus oxycephalus(belongs to Bodianinae)and Pseudolabrus sieboldi(belongs to Pseudolabrus) clustered in a clade first, and formed a sister relationship with Halichoeres melanurus, and then Cheilinus undulates. This result preliminarily supported Bodianinae has a closer relationship with Pseudolabrus.(4) Molecular clock results, which based on 36 encoding genes of mitochondrial genome, revealed that the divergence time of the fishes of Labridae probably originated in the late Eocene to Oligocene time and may further evoled to modern characteristic labridae species in Miocene.