The role of mitonuclear interactions in thermal and dietary adaptation

Abstract

Mitochondria play a key role in energy metabolism through cellular respiration. Despite their importance, they are uniquely exposed to perturbation because their functions depend on the correct interaction between two distinct genomes, the mitochondrial and the nuclear DNA. Even mild incompatibilities between the two genomes could impact mitochondrial functions with downstream repercussions on individual fitness. Climate change predictions estimate an increase in temperature and its variability, changes in food web structures, but also in the distribution of populations. Events that may generate mitonuclear mismatches (e.g. hybridization between separate populations) are therefore expected to increase in frequency following the shifts in thermal niches. In addition, temperature and dietary regimes are well-known metabolic stressors whose variation can potentially exacerbate mitonuclear incompatibilities. The aim of this research was to test how far mitonuclear interactions contribute to thermal and dietary adaptation or breakdown in changing environments. I employed experimental lines of the fruitfly Drosophila melanogaster, characterized by mitonuclear match or mismatch, to investigate the combined impact of mitonuclear genotype, temperature, and diet modulation over a wide array of phenotypic traits, including mitochondrial functions, reactive oxygen species metabolism and life-history trade-offs. Results suggest that mitonuclear interactions might impact organismal fitness in an unpredictable way, potentially influencing local adaptation in a mutating world.