Acclimation to daily thermal variability drives the metabolic performance curve

Background: Among the predictions of the effect of future climate change, the impact of thermal conditions at local levels on the physiological performance of individuals and their acclimation capacities is key to understanding animals' responses to global warming. Goal: Test for the effect of acclimation to environmental thermal variability, namely 24 plus or minus 0 degree C, 24 plus or minus 4 degree C, and 24 plus or minus 8 degree C, on the metabolic performance curve in the mealworm beetle Tenebrio molitor. Results: Maximum resting metabolism and metabolic breadth were significantly different, but optimal temperature was similar, between treatments. Thus, increases in ambient thermal variability caused a reduction in maximum performance at each level of acclimation, with a decrease of almost 50% between the nil variability and plus or minus 8 degree C daily variability treatments. Conclusions: If thermal variability changes in any of the directions forecast by climatologists, ecologists will have to use mechanistic and modelling approaches based on physiological and biophysical traits to predict the biodiversity consequences of climate change.