Abstract
BackgroundThe family Labridae made up of 519 species in the world. The functional evolution of the feeding-related jaws leaded to differentiation of species, and the pharyngeal jaw apparatus evolved independently, but evolutionary mechanism still remain unaddressed in wrasses. Mitogenomes data can be used to infer genetic diversification and investigate evolutionary history of wrasses, whereas only eight complete mitogenomes in this family have been sequenced to date. Here, we sequenced the complete mitogenomes of Iniistius trivittatus to investigate genetic differentiation among wrasse species.ResultsWe sequenced the complete mitogenomes of I. trivittatus using a novel PCR strategy. The I. trivittatus mitogenomes is 16,820 bp in length and includes 13 protein -coding genes, 2 ribosomal RNA (rRNA) genes, 22 transfer RNA (tRNA) genes, and a control region. Compared to eight known mitochondrial genome, 2 additional noncoding regions (lengths of 121 and 107 bp), or so-called inserts, are found in the intergenic regions 12S rRNA - tRNAVal - 16S rRNA. The presumed origin of the two rare inserts is from tRNA- related retrotransposons. Compared with cytochrome b gene, the two insert sequences are highly conserved at the intraspecies level, but they showed significant variation and low similarity (< 70%) at the interspecies level. The insert events were only observed in I. trivittatus by checking the phylogenetic trees based on the complete mitogenomes of Labrida species. This finding provides evidence that in the mitogenomes, retrotransposon inserts result in intraspecific homoplasmy and interspecific heteroplasmy by natural selection and adaptation to various environments.ConclusionsThis study found additional mitogenome inserts limited in wrasse species. The rRNA genes with inserts might have experienced a selective pressure for adaptation to feeding modes. Such knowledge can enable a better understanding of molecular mechanism underlying morphological evolution in wrasses.
Highlights
The family Labridae made up of 519 species in the world
Most of the genes were encoded on the H-strand, while 8 transfer RNA (tRNA) genes and ND6 were on the L-strand (Table 1)
Two novel inserted noncoding regions, NCR1 and NCR2, were found in I. trivittatus Mitochondrial DNA (mtDNA)
Summary
The family Labridae made up of 519 species in the world. Mitogenomes data can be used to infer genetic diversification and investigate evolutionary history of wrasses, whereas only eight complete mitogenomes in this family have been sequenced to date. We sequenced the complete mitogenomes of Iniistius trivittatus to investigate genetic differentiation among wrasse species. There are approximately 519 known species of Labridae belonging to 71 genera in the world [2]. There are 150 species of labrid fishes within 38 genera in China, representing approximately 28.9% of the species worldwide [3]. Hybrids have been described in labrid fishes [4]. These characteristics cause problems in species identification via morphological characteristics for some species
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