不同食性雁形目鸟类线粒体基因组的适应性进化分析

Adaptive Evolution Analysis of Mitochondrial Genomes in Anseriform Birds with Various Feeding Habits

以往的研究表明,动物的食性与能量代谢及生存适应密切相关。能量代谢主要发生在线粒体中,线粒体编码的13个蛋白质亚基是氧化磷酸化复合体的重要组成部分。雁形目鸟类的食性主要包括肉食性、杂食性和植食性3种类型。为了分析食性对鸟类基因组进化的影响,研究选取了20种雁形目鸟类,并根据食性分成3组,下载其线粒体基因组,通过适应性进化分析、放松性选择分析、多态性氨基酸位点检测以及3D结构预测分析,研究这3组鸟类的线粒体蛋白编码基因在进化上的表现。结果发现,食肉组鸟类线粒体基因组的进化速率高于食草组和杂食组鸟类,并且只有食肉组鸟类线粒体蛋白编码基因受到了放松性的选择压力作用。此外,多态性氨基酸位点检测表明,食肉组线粒体基因组编码的蛋白质中,多态性位点和有害位点数量远高于食草组和杂食组。而杂食组鸟类线粒体蛋白编码基因进化速率较低,大部分基因受到强化性选择作用,蛋白质序列中的多态性位点也较少。研究结果表明,不同食性的雁形目鸟类,其线粒体基因组编码的蛋白质受到了不同的选择压力,这为食性差异影响鸟类线粒体基因组适应性进化提供了分子依据。

Previous studies showed that,animals'feeding habits are related to their energy metabolism and adaptation.Energy metabolism takes place in mitochondria,and 13 subunits of the oxidative phosphorylation complexes were encoded by mitochondrial genome.According to feeding habits,birds of Anteriformes could be divided into three groups,including carnivorous,herbivorous and omnivorous.To study the evolutionary effects of feeding habit on mitogenomes,we selected 20 anteriformes species and divided them into three groups.We downloaded their mitogenomes,and did adaptive analysis,relax analysis,polymorphism analysis and 3D structure prediction.Our results showed that,the carnivorous group had higher evolutionary rates than the other two groups,and only the carnivorous group had multiple genes under relaxed selection.Meanwhile,the carnivorous group had more polymorphism sites and deterious sites among their proteins sequences than the other two groups.The genes from the omnivorous group showed decreased evolutionary rates,and most of the genes were under intensification selection,furthermore,less polymorphic sites were detected in this group.The results indicated that the proteins encoded by mitochondrial genomes of anteriformes birds with different feeding habits are subject to different selective pressures.This study provides a molecular basis for the influence of dietary differences on the adaptive evolution of avian mitochondrial genomes.