Meeting Abstract
Mitochondrial function is critical for energy homeostasis and should thus shape how genetic variation in metabolism is transmitted through levels of biological organization to generate stability in organismal performance. Mitochondrial function is encoded by genes in two distinct and separately inherited genomes, and selection to maintain mitonuclear interactions is often intense. The frequently observed high levels of polymorphism in genes involved in mitonuclear interactions and variation for mitochondrial function is thus surprising and demands explanation. Potamopyrgus antipodarum, a New Zealand snail with coexisting sexual and asexual individuals and, accordingly, contrasting systems of separate vs. co-inheritance of nuclear and mitochondrial genomes, provides a powerful means to dissect the evolutionary and functional consequences of mitonuclear variation. The lakes inhabited by P. antipodarum span wide environmental gradients, with substantial across-lake genetic structure and mitonuclear discordance. We can therefore make comparisons across reproductive modes and lakes to partition variation in cellular respiration across genetic and environmental axes. Here, we integrated cellular, physiological, and behavioral approaches to quantify variation in mitochondrial function across wild P. antipodarum lineages. We found extensive across-lake variation in organismal oxygen consumption and behavioral response to heat stress, coupled with elevated mitochondrial membrane potential in males. These data set the stage for applying this important model system for sex and polyploidy to dissect the relationship between mitonuclear variation, performance, plasticity, and fitness in natural populations.
