Fisheries College, Zhejiang Ocean University, Zhoushan, Zhejiang, China.
PLoS One. 2022 Oct 13;17(10):e0276056. doi: 10.1371/journal.pone.0276056. eCollection 2022.
The mitochondrial genome plays a crucial role in the balance of energy and heat production in organisms and, thus, may be under natural selection due to its potential role in adaptive divergence and speciation. Here, we studied natural selection on the mitogenome of Acrossocheilus (Cypriniformes: Cyprinidae), a genus of fish that inhabits a broad latitudinal distribution ranging from the tropics and subtropics through temperate regions. Specifically, we used 25 published mitogenome sequences of Acrossocheilus species to investigate phylogenetic relationships in this genus and detected signals of positive selection on 13 protein-coding, mitochondrial genes. We found that relaxed purifying selection and genetic drift were the predominant evolutionary forces acting on the analyzed mitogenomes. However, we also found evidence of diversifying selection on some codons, indicating episodes of positive selection. Additionally, we analyzed the mitogenomic data within an environmental modeling framework and found that the Ka/Ks ratio of ATP6 may correlated with a mean diurnal temperature range (p = 0.0449), while the Ka/Ks ratio of COX2 may correlated with precipitation during the driest month (p = 0.00761). These results suggest that the mitogenomes of Acrossocheilus species may be involved in evolutionary adaptations to different habitats. Based on this, we believe that our study provides a new insight into the role of the mitochondrial genome of Acrossocheilus species in adaptation to different environments. During our study, we also discovered several cases of paraphyly and polyphyly among accessions of species and their putative synonyms. Thus, our study suggests that a careful reassessment of the taxonomy of Acrossocheilus is using high-quality molecular data merited.
线粒体基因组在生物体的能量和热量产生平衡中起着至关重要的作用，因此，由于其在适应性分化和物种形成中的潜在作用，它可能受到自然选择的影响。在这里，我们研究了横跨鱼属（鲤形目：鲤科）线粒体基因组的自然选择，横跨鱼属是一种鱼类，栖息在从热带和亚热带到温带的广泛纬度分布区。具体来说，我们使用了 25 个已发表的横跨鱼属物种的线粒体基因组序列来研究这个属的系统发育关系，并在 13 个线粒体蛋白编码基因上检测到了正选择的信号。我们发现，放松的净化选择和遗传漂变是作用于分析的线粒体基因组的主要进化力量。然而，我们也发现了一些密码子上的多样化选择的证据，表明存在正选择事件。此外，我们在环境建模框架内分析了线粒体基因组数据，并发现 ATP6 的 Ka/Ks 比值可能与日平均温度范围相关（p = 0.0449），而 COX2 的 Ka/Ks 比值可能与最干旱月的降水相关（p = 0.00761）。这些结果表明，横跨鱼属物种的线粒体基因组可能参与了对不同生境的进化适应。基于此，我们认为我们的研究为横跨鱼属物种的线粒体基因组在适应不同环境方面的作用提供了新的见解。在我们的研究过程中，我们还发现了一些物种及其假定的同义词的种系之间的并系和多系现象。因此，我们的研究表明，使用高质量的分子数据对横跨鱼属的分类学进行仔细的重新评估是值得的。
