The 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. We 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. This 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.

中文翻译：

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Iniistius trivittatus 的完整线粒体基因组以及在濑鱼中观察到的 rRNA 和 tRNA 基因之间两个插入片段的独特变异。


世界上有 519 个物种，属于 Labridae 科。与摄食相关的颌部的功能进化导致了物种的分化，咽颌装置独立进化，但濑鱼的进化机制仍未得到解决。线粒体基因组数据可用于推断濑鱼的遗传多样性和研究进化史，而迄今为止，该家族中只有八个完整的线粒体基因组已被测序。在这里，我们对 Iniistius trivittatus 的完整线粒体基因组进行了测序，以研究濑鱼物种之间的遗传分化。我们使用一种新的 PCR 策略对 I. trivittatus 的完整线粒体基因组进行了测序。 I. trivitatatus 线粒体基因组长度为 16,820 bp，包括 13 个蛋白质编码基因、2 个核糖体 RNA (rRNA) 基因、22 个转移 RNA (tRNA) 基因和一个控制区。与八个已知的线粒体基因组相比，在基因间区域 12S rRNA - tRNAVal - 16S rRNA 中发现了 2 个额外的非编码区域（长度为 121 和 107 bp）或所谓的插入片段。两个罕见插入片段的推测来源是 tRNA 相关的逆转录转座子。与细胞色素b基因相比，这两个插入序列在种内水平上高度保守，但在种间水平上表现出显着的变异和较低的相似性(< 70%)。仅通过检查基于拉布里达物种完整线粒体基因组的系统发育树，在 I. trivittatus 中观察到插入事件。这一发现提供了证据，证明在有丝分裂基因组中，逆转录转座子插入通过自然选择和对各种环境的适应而导致种内同质性和种间异质性。这项研究发现额外的线粒体基因组插入仅限于濑鱼物种。 带有插入片段的 rRNA 基因可能经历了适应喂养模式的选择压力。这些知识可以更好地理解濑鱼形态进化的分子机制。