High prevalence of non-synonymous substitutions in mtDNA of cichlid fishes from Lake Victoria.
High prevalence of non-synonymous substitutions in mtDNA of cichlid fishes from Lake Victoria.
复制标题
维多利亚湖慈鲷线粒体 DNA 中非同义替换的发生率很高。
DOI：
10.1016/j.gene.2014.09.039
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发表时间：
2014
期刊：
影响因子：
3.5
通讯作者：
Tachida H.
中科院分区：
文献类型：
--
作者：
Shirai K;Inomata N;Mizoiri S;Aibara M;Terai Y;Okada N;Tachida H.
当种群规模减少时，遗传漂变可能会修复轻微有害的突变，预计非同义替换会增加。有人认为，过去的干旱已经严重影响和减少了维多利亚湖的慈鲷鱼种群，而地理研究表明，坦噶尼喀湖和马拉维湖的水位保持相当稳定。在后两个湖泊中的非稳定环境可能使慈鲷鱼的种群数量足够大，以消除轻微的有害突变。维多利亚湖和坦噶尼喀湖和马拉维湖之间的慈鲷鱼种群规模的稳定性的差异，预计会导致不同的非同义/同义比，ω（=dN/dS），进化速度。在这里，我们估计ω和比较它之间的三个湖泊慈鲷的13个线粒体蛋白编码基因使用最大似然法。我们发现，在维多利亚湖慈鲷科鱼类的血统有一个显着较高的几个线粒体基因座的ω。此外，在维多利亚湖丽鱼科鱼类的mtDNA中的几个密码子的正选择。我们的研究结果表明，适应性和轻微有害的分子进化发生在维多利亚湖慈鲷的mtDNA基因，其非同义位点通常是保守的。
When a population size is reduced, genetic drift may fix slightly deleterious mutations, and an increase in nonsynonymous substitution is expected. It has been suggested that past aridity has seriously affected and decreased the populations of cichlid fishes in Lake Victoria, while geographical studies have shown that the water levels in Lake Tanganyika and Lake Malawi have remained fairly constant. The comparably stable environments in the latter two lakes might have kept the populations of cichlid fishes large enough to remove slightly deleterious mutations. The difference in the stability of cichlid fish population sizes between Lake Victoria and the Lakes Tanganyika and Malawi is expected to have caused differences in the nonsynonymous/synonymous ratio, ω (=dN/dS), of the evolutionary rate. Here, we estimated ω and compared it between the cichlids of the three lakes for 13 mitochondrial protein-coding genes using maximum likelihood methods. We found that the lineages of the cichlids in Lake Victoria had a significantly higher ω for several mitochondrial loci. Moreover, positive selection was indicated for several codons in the mtDNA of the Lake Victoria cichlid lineage. Our results indicate that both adaptive and slightly deleterious molecular evolution has taken place in the Lake Victoria cichlids' mtDNA genes, whose nonsynonymous sites are generally conserved.