Keeping it cool to take the heat: tropical lizards have greater thermal tolerance in less disturbed habitats

Abstract

Global climate change has profound effects on species, especially those in habitats already altered by humans. Tropical ectotherms are predicted to be at high risk from global temperature increases, particularly those adapted to cooler temperatures at higher altitudes. We investigated how one such species, the water anole (Anolis aquaticus), is affected by temperature stress similar to that of a warming climate across a gradient of human-altered habitats at high elevation sites. We conducted a field survey on thermal traits and measured lizard critical thermal maxima across the sites. From the field survey, we found that (1) lizards from the least disturbed site and (2) operative temperature models of lizards placed in the least disturbed site had lower temperatures than those from sites with histories of human disturbance. Individuals from the least disturbed site also demonstrated greater tolerance to high temperatures than those from the more disturbed sites, in both their critical thermal maxima and the time spent at high temperatures prior to reaching critical thermal maxima. Our results demonstrate within-species variability in responses to high temperatures, depending on habitat type, and provide insight into how tropical reptiles may fare in a warming world.

Keywords: Anolis; Anthropogenic effects; CTmax; Costa Rica; Microhabitat; Primary forest; Secondary forest; Thermoconformer.