Data from: Cold-adaptation increases rates of nutrient flow and metabolic plasticity during cold exposure in (Drosophila melanogaster)

Metabolic flexibility is an important component of adaptation to stressful environments, including thermal stress and latitudinal adaptation. A long history of population genetic studies suggest that selection on core metabolic enzymes may shape life histories by altering metabolic flux. However, the direct relationship between selection on thermal stress hardiness and metabolic flux has not previously been tested. We investigated flexibility of nutrient catabolism during cold stress in Drosophila melanogaster artificially selected for fast or slow recovery from cold-coma (cold-hardy and -susceptible), specifically testing the hypothesis that stress adaptation affects metabolic flux. Using 13C-labeled glucose, we first showed that cold-hardy flies more rapidly incorporate ingested carbon into amino acids and newly synthesized glucose, permitting synthesis of protective molecules essential for resisting cold stress. Second, using glucose and leucine tracers we showed that cold-hardy flies had higher oxidation rates than cold-susceptible flies before cold exposure, greater metabolic suppression during the cold-stress exposure, and returned to higher oxidation rates during recovery. Increased plasticity in substrate catabolism may allow cold-adapted flies to resist gradual loss of metabolic homeostasis in the cold, by suppressing substrate catabolism during cold exposure and thus maintaining energy balance in the face of reduced demand. This work illustrates for the first time the differences in nutrient fluxes that underpin cold adaptation, suggesting that metabolic costs associated with cold hardiness could invoke resource-based trade-offs that shape life histories.