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

Abstract

When animals are exposed to higher-than-optimal temperatures, they are expected to thermoregulate by decreasing their activity and seeking cooler areas. However, individuals of certain species continue performing reproductive behaviors instead of thermoregulatory behaviors during challenging conditions. This trade-off has been demonstrated in aquatic animals, but not in terrestrial ectotherms. This research gap is important given the relevance of survival-reproduction trade-offs in evolutionary ecology and the pace of current habitat warming. We explored this potential trade-off in territorial males of the lizard Sceloporus ochoterenae, which mate during the hot-dry season in seasonally dry tropical forest. We first assessed the existence of a temporal trade-off between performing push-ups (territorial behavioral display) versus sheltering in the shade (thermoregulatory behavior), then used confirmatory path analysis to explore how it was affected by tree cover, microclimate temperature, and the presence of a conspecific intruder. We found that territories with less tree 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 loss of moisture and energy reserves, perhaps because the display is more effective when performed in the open. The potential effects of continued habitat warming on this trade-off could intensify it or driving lizards to change their daily activity rhythms.