Beyond thermal limits: comprehensive metrics of performance identify key axes of thermal adaptation in ants

How species respond to temperature change depends in large part on their physiology. Physiological traits, such as critical thermal limits (CTmax and CTmin), provide estimates of thermal performance but may not capture the full impacts of temperature on fitness. Rather, thermal performance likely depends on a combination of traits—including thermal limits—that vary among species.
Here we examine how thermal limits correlate with the main components that influence fitness in ants. First, we compare how temperature affected colony survival and growth in two ant species that differ in their responses to warming in the field—Aphaenogaster rudis (heat-intolerant) and Temnothorax curvispinosus (heat-tolerant). We then extended our study to compare CTmax, thermal requirements of brood, and yearly activity season among a broader set of ant species.
While thermal limits were higher for workers of T. curvispinosus than A. rudis, T. curvispinosus colonies also required higher temperatures for su...