Meeting Abstract
Mismatch between nuclear and mitochondrial genomes is a potentially strong driver of physiological adaptation, yet challenging to investigate due to reduced reproductive success of parents and performance of offspring. In montane populations of the leaf beetle Chrysomela aeneicollis, variation at the glycolytic enzyme locus phosphoglucose isomerase (Pgi) and the mitochondrion is concordant along a north to south thermal gradient. Recent studies of naturally-introgressing populations show that performance and reproductive success of mitonuclear mismatched individuals is lower than individuals with matched genomes, especially after exposure to physiological stress. To directly investigate how the mitochondrion is interacting with nuclear gene products to cause these patterns, a large number of matched and mismatched offspring of known mitochondrial type is required. To test feasibility of generating such individuals, adult beetles were collected from populations at the northern (N) and southern (S) edges of C. aeneicollis’ latitudinal range in the Sierra Nevada, sorted by sex and allowed to mate with a partner of the same (NfNm, SfSm) or opposite (NfSm, SfNm) origin. Male mating frequency was lowest for NfNm pairs and highest for SfSm pairs. In contrast, fecundity was 50% lower for NfSm females than SfNm ones, a directional mismatch that may be due to mitonuclear incompatibility. Fecundity was intermediate for same-site crosses. For larvae, running speed after heat stress was significantly lower for NfSm and SfNm offspring than those from same-site crosses. Studies of mitochondrial physiology and genetics are underway. Results to date demonstrate feasibility of laboratory crosses to alter adult reproductive success and generate offspring that differ in physiological performance characters among mitonuclear types.
