AN EXCEPTION FOR THE RULE? THE THERMAL ECOLOGY OF A TROPICAL LIZARD

PAIVA, TALES M. A.; CARREIRA BRUINJÉ, ANDRE; COSTA, GABRIEL C.

Congreso; 3th International Symposium of Ecology; 2018

For lizards, temperature is a key factor that has direct consequences to organismal survival and reproduction. In comparison to temperate species, tropical lizards have a low thermal safety, meaning that an increase in mean environmental temperatures could drive tropical populations towards extinction more easily than temperate populations. Considering this general prediction for tropical lizards, our main goal here was to determine the thermal safety of Tropidurus semitaeniatus, a rock dwelling lizard endemic to the Brazilian Caatingas. We collected several thermal variables and adopted Warming Tolerance (WT), a metric used in the prediction above mentioned. We collected lizards in three different natural populations and measured their body temperature (Tb), preferred temperature (Tpref), maximal temperature tolerated (CTmax) and habitat temperature (Thabitat). WT is determined by the difference between the CTmax and Thabitat. We found that T. semitaeniatus has a Tb = 34.9°C, Thabitat = 35.5°C, Tpref = 37.9°C and CTmax = 43.8°C. Thus, WT = 8.3°C. Two major results can be observed. Firstly, on the contrary to expectations for tropical lizards, we found a high WT. Secondly, this species has body temperatures at the wild below its preferred temperatures. The fist result suggests that the thermal safety of T. semitaeniatus is high enough to resist the elevations on temperature predicted for the current century, considering all possible scenarios of IPCC?s expectations on south-american regions. The second result can be a consequence of thermoregulatory behavior presented by T. semitaeniatus, which provides to lizards an effective advantage to overcome overheating. Our results highlight the importance of thermal studies in species level to find cases apart from generalizations. This would raise questions about the causes of such mismatch. Studies with tropical species inhabiting regions with different climate dynamics are necessary for a better understanding of deleterious impacts of global climate changes on tropical lizards.