Correlates of avian flight mode variation with mitochondrial substitution rates: a comparative phylogenetic analysis

Abstract Mitochondria power animal locomotion through oxidative phosphorylation, but ATP production generates reactive oxygen species (ROS) that damage mitochondrial DNA (mtDNA). Due to imperfect repair mechanisms, this oxidative stress can elevate mtDNA mutation rates. Birds exhibit distinct flight modes—energy-intensive flapping versus efficient soaring—suggesting potential differential mtDNA mutation rates. However, the relationship between flight mode and mtDNA mutation rates in birds has received little attention. We investigated this link by comparing synonymous substitution rates between soaring and flapping species. Our phylogenetic comparative analysis demonstrated that flight mode evolution has shaped mitochondrial mutation rates in birds. This work reveals significant covariation between flight mode evolution and mitochondrial mutation rates, providing novel mechanistic insight into how locomotor intensity drives molecular evolution through oxidative stress pathways.