Meeting Abstract
Organisms differ in resource allocation towards life history traits including growth, reproduction, activity, and maintenance, thus defining their life history strategy and metabolic demands. Variable energetic demands are met via differential flux of ingested nutrients through metabolism. Central metabolic pathways converge in the mitochondria, making this organelle the epicenter of life history allocations. We hypothesized that alternative life history allocations are underpinned by differences in mitochondrial function and tested the prediction that mitochondrial plasticity accompanies shifts in life history energy demands. Morphs of the wing-polymorphic cricket Gryllus firmus specialize either in dispersal (LW) or reproduction (SW). In early adulthood, LWs maintain functional flight muscle and accumulate lipid stores for flight, while SWs invest in ovary growth to reach an early reproductive maturity. Using high resolution respirometry, we characterized rates of mitochondrial respiratory function (State III, State IV, Cytochrome c oxidase capacity (CCO)) when fueled by multiple substrates (pyruvate, malate, glutamate, succinate) of LW and SW female adults across ontogeny (1, 3 or 5 day-old). At day one, mitochondrial respiration was similar in the morphs but diverged gradually, such that by the time LW are prepared to fly and SW have completed ovary synthesis, State III was significantly higher in LW than SW. CCO was correlated with State III suggesting that alterations in mitochondrial densities may underlie observed mitochondrial plasticity. Overall, these results indicate that divergence of mitochondrial respiration may be integral to the expression and constraint of life history strategies.
