Temporal trade-off between territorial and thermoregulatory behaviors of a generalist lizard in a dry forest

Abstract

Abstract Avoiding dangerously hot body temperatures is important for survival, but animals may perform reproductive behaviors at the expense of behaviors used to cool down (or vice-versa), resulting in a thermoregulation-reproduction trade-off. Although this trade-off has been demonstrated in semi-aquatic animals, it has not been studied in terrestrial ectotherms. This is an important research gap given the importance of survival-reproduction trade-offs in evolutionary ecology and the pace of habitat warming due to vegetation loss and global climate change. We explored this trade-off in territorial males of the lizard Sceloporus ochoterenae, which mates during the hot-dry season in seasonally dry tropical forest. We first confirmed the existence of a temporal trade-off between performing push-ups (a territorial behavioral display) versus sheltering in the shade (thermoregulatory behavior), then used confirmatory path analysis to explore how it is affected by vegetation cover, microclimate temperature, and the presence of a conspecific intruder. We found that territories with less vegetation cover had higher microclimate temperatures, where focal males spent more time performing push-ups at the expense of sheltering in the shade. Focal males also spent more time performing push-ups the longer an intruder was present, who was also affected by the environmental variables. Territorial males spent more time in sunny spots when performing push-ups despite the potential for overheating, perhaps because the display is more effective when performed in the open. The potential effects of continued habitat warming on this trade-off vary widely, including intensifying it, driving lizards to change their daily activity rhythms, and chronic overheating.