Evaluating the role of melanic coloration and environmental conditions on heat gain among patagonian lizards (Liolaemus fitzingerii group)

ESCUDERO, PAULA C.; SÁNCHEZ, KEVIN I.; AVILA, LUCIANO J.

South American Journal of Herpetology

Sociedade Brasileira de Herpetologia

Año: 2024

1808-9798

The performance of ectotherms in their environment is predominantly shaped by body temperature, which is contingent upon the interplay of environmental conditions and their capacity to regulate heat exchange. Thermoregulation involves costs (e.g. energy costs and fitness costs), which can be buffered by behavioral, physiological, and/or biophysical mechanisms (e.g. coloration). Here, we evaluated how differences in heating rates in individuals of Liolaemus melanops and L. xanthoviridis of the L. fitzingerii group are correlated with phenotypic traits expected to influence heat gain (melanic coloration and body size). Also, we investigated whether environmental conditions are correlated with heating rates in these two species. We collected adult males of coastal and plateau localities of both species. We measured heating rates, mass, and melanism in laboratory conditions. Moreover, we obtained environmental variables from each collecting site. Our results showed that heating rates were influenced only by the individual´s mass, where slender lizards heated faster than heavier lizards. Our results did not provide evidence for the color-mediated thermoregulation hypothesis, which posits that assuming a similar body size, melanic ectothermic individuals should heat faster and reach higher equilibrium temperatures than lighter ones. Also, we did not find evidence that the different environmental conditions of the coastal and plateau localities affected heating rate. In these species of Liolaemus, behavioral and physiological adjustments could be the key mechanisms driving active thermoregulation.