Evidence for locally adaptive metabolic rates among ant populations along an elevation gradient

1. As global temperatures rise, the mechanistic links between temperature, physiology and behavior will increasingly define predictions of ecological change. However, for many taxa, we currently lack consensus about how thermal performance traits vary within and across populations, and whether and how locally adaptive trait plasticity can buffer warming effects.
2. The metabolic cold adaptation hypothesis posits that cold environments (e.g. high elevations and latitudes) select for high metabolic rates (MR), even after controlling for body size differences, and that this enables high activity levels when an organism is near its cold lower thermal limits. Steep MR reaction norms are further predicted at cold temperatures to enable rapid behavioral activation with rising temperatures needed to exploit brief thermal windows suitable for performing eco-evolutionary tasks.
3. We tested these predictions by performing common garden experiments comparing thermal reaction norms of MR (from 15...