Thermal ecology and thermoregulatory behaviour of Tropidurus hispidus and T. semitaeniatus in a caatinga area of northeastern Brazil

This study assessed the thermal ecology of Tropidurus hispidus and T. semitaeniatus in a caatinga area in the state of Rio Grande do Norte, Brazil. The mean activity body temperature of T. semitaeniatus (35.1±2.0 °C) was significantly higher than that of T. hispidus (33.6±2.3 °C). While there was no seasonal variation in the body temperature of T. hispidus, it was significantly higher for T. semitaeniatus in the wet season compared to the dry season. Substrate temperature was the best predictor of body temperature in T. hispidus in both seasons, whereas for T. semitaeniatus substrate and air temperatures were the best predictors of lizard temperature in the wet and dry season, respectively. During the dry season, both species spent more time in the shade or under filtered sunlight. In the wet season, T. hispidus did not prefer areas with specific light exposures, whereas T. semitaeniatus predominantly spent time exposed to the sun or under filtered sunlight. We conclude that the similarity in temperature ranges during activity of T. hispidus and T. semitaeniatus most likely reflects their common phylogenetic origin and foraging mode, whereas the differences in thermal behaviour may be due to their particular adaptations to their local, seasonal habitat.