Claramunt Santiago, Haddrath Oliver
Department of Ecology and Evolutionary Biology, University of Toronto, Toronto, Ontario, Canada.
Department of Natural History, Royal Ontario Museum, Toronto, Ontario, Canada.
Genome Biol Evol. 2023 Oct 6;15(10). doi: 10.1093/gbe/evad173.
Mitochondrial genomes are expected to show adaptations for optimizing aerobic respiration in birds that make intense use of flight. However, there is limited empirical evidence of such a relationship. We here examine correlates of several mitochondrial genome characteristics and flight use across a diverse sample of 597 bird species. We developed an index of flight use intensity that ranged from 0 in flightless species to 9 in migratory hummingbirds and examined its association with nucleobase composition, amino acid class composition, and amino acid site allelic variation using phylogenetic comparative methods. We found no evidence of mitochondrial genome adaptations to flight intensity. Neither nucleotide composition nor amino acid properties showed consistent patterns related to flight use. While specific sites in mitochondrial genes exhibited variation associated with flight intensity, there was limited association between specific amino acid residues and flight intensity levels. Our findings suggest a complex genetic architecture for aerobic performance traits, where multiple genes in both mitochondria and the nucleus may contribute to overall performance. Other factors, such as gene expression regulation and anatomical adaptations, may play a more significant role in influencing flight performance than changes in mitochondrial genes. These findings highlight the need for comprehensive genomic analyses to unravel the intricate relationship between genetic variants and aerobic performance in birds.
线粒体基因组有望展现出适应性，以优化那些大量使用飞行能力的鸟类的有氧呼吸。然而，这种关系的实证证据有限。我们在此研究了597种鸟类的不同样本中，几种线粒体基因组特征与飞行能力使用之间的相关性。我们制定了一个飞行能力使用强度指数，范围从不会飞的物种的0到迁徙蜂鸟的9，并使用系统发育比较方法研究了它与核碱基组成、氨基酸类别组成以及氨基酸位点等位基因变异之间的关联。我们没有发现线粒体基因组适应飞行强度的证据。核苷酸组成和氨基酸特性均未显示出与飞行能力使用相关的一致模式。虽然线粒体基因中的特定位点表现出与飞行强度相关的变异，但特定氨基酸残基与飞行强度水平之间的关联有限。我们的研究结果表明，有氧性能特征具有复杂的遗传结构，线粒体和细胞核中的多个基因可能对整体性能都有贡献。其他因素，如基因表达调控和解剖学适应，可能在影响飞行性能方面比线粒体基因的变化发挥更重要的作用。这些发现凸显了进行全面基因组分析以揭示鸟类遗传变异与有氧性能之间复杂关系的必要性。
