City limits: Heat tolerance is influenced by body size and hydration state in an urban ant community.

Cities are rapidly expanding, and global warming is intensified in urban environments due to the urban heat island effect. Therefore, urban animals may be particularly susceptible to warming associated with ongoing climate change. We used a comparative and manipulative approach to test three related hypotheses about the determinants of heat tolerance or critical thermal maximum ( ) in urban ants-specifically, that (a) body size, (b) hydration status, and (c) chosen microenvironments influence .