Complete mitochondrial genomes of eight seahorses and pipefishes (Syngnathiformes: Syngnathidae): insight into the adaptive radiation of syngnathid fishes
Complete mitochondrial genomes of eight seahorses and pipefishes (Syngnathiformes: Syngnathidae): insight into the adaptive radiation of syngnathid fishes
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八种海马和海龙（Syngnathiformes：Syngnathidae）的完整线粒体基因组：深入了解海马和海龙鱼的适应性辐射
DOI：
10.1186/s12862-019-1430-3
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发表时间：
2019-06-11
影响因子：
3.4
通讯作者：
Lin, Qiang
中科院分区：
文献类型：
--
作者：
Wang, Xin;Zhang, Yanhong;Lin, Qiang
雄性妊娠的进化是合颌纲生物最显著的特征，其特殊的生活史特征使合颌纲物种成为生物进化中许多问题的优秀模式物种。然而，合胞体的起源和不同合胞体物种的进化分化时间仍不清楚。综合系统发育研究将为阐明其起源、进化和分布模式提供关键证据。结果本研究对8种合颌鱼的线粒体基因组进行了测序，估计的分化时间表明，在始新世时期，合颌鱼与其他硬骨鱼的分化时间约为48.8万年。选择分析表明，合颌鱼的许多线粒体基因的ka / ksvalue明显低于其他硬骨鱼。与其他硬骨鱼相比，合鳃鱼中最常用的两个密码子不同，线粒体简单序列重复序列（SSRs）分布在非编码序列中的比例更大。结论合颌鱼在种群爆发初期经历了一个适应性辐射过程。与其他硬骨鱼相比，合骨鱼线粒体OXPHOS基因似乎表现出较低的ka / ks比值，这可能表明它们的有丝分裂基因组经历了强烈的选择性限制，以消除有害突变。
BackgroundThe evolution of male pregnancy is the most distinctive characteristic of syngnathids, and their specialized life history traits make syngnathid species excellent model species for many issues in biological evolution. However, the origin of syngnathids and the evolutionary divergence time of different syngnathid species remain poorly resolved. Comprehensive phylogenetic studies of the Syngnathidae will provide critical evidence to elucidate their origin, evolution, and dispersal patterns.ResultsWe sequenced the mitochondrial genomes of eight syngnathid species in this study, and the estimated divergence times suggested that syngnathids diverged from other teleosts approximately 48.8 Mya during the Eocene period. Selection analysis showed that many mitochondrial genes of syngnathids exhibited significantly lowerKa/Ksvalues than those of other teleosts. The two most frequently used codons in syngnathid fishes were different from those in other teleosts, and a greater proportion of the mitochondrial simple sequence repeats (SSRs) were distributed in non-coding sequences in syngnathids compared with other teleosts.ConclusionsOur study indicated that syngnathid fishes experienced an adaptive radiation process during the early explosion of species. Syngnathid mitochondrial OXPHOS genes appear to exhibit depressedKa/Ksratios compared with those of other teleosts, and this may suggest that their mitogenomes have experienced strong selective constraints to eliminate deleterious mutations.