Meeting Abstract
11.2 Saturday, Jan. 4 10:30 Thermal Ecology of Podarcis tiliguerta (Lacertidae) Across an Altitudinal Gradient MAYERL, C.J.*; VAN DAMME, R.; Clemson University, SC cmayerl@clemson.edu
Most aspects of behavioral and physiological performance in lizards depend on body temperature (Tb). Environmental temperatures (Tes) are among the most important external factors influencing Tb in ectotherms. Elevation has a powerful impact on Tes, and organisms exhibit many responses to the colder Tes experienced at high elevation. There are two contrasting views on the evolutionary adaptability of thermal physiology: the ‘static’ view, which predicts that thermal physiology is resistant to directional selection, and the ‘labile’ view, which predicts susceptibility to directional selection. Size, condition, thermoregulatory behavior, Tb, skin absorptivity, heating rate and abundance of two populations of the Tyrrhenian Wall lizard, Podarcis tiliguerta (Lacertidae) at two altitudes in Corsica, France (250 m and 1,450 m) were studied, and predation pressure and the quality of the thermal habitat at both elevations were estimated. High elevation lizards showed no shift in thermoregulation, and did not absorb more solar radiation than conspecifics at low elevation, resulting in them having lower Tbs with equivalent heating rates. Despite this, the abundance of lizards at each location was equal, and lizards at high elevation were both larger and in better body condition than those at low elevation. Predation pressure was also lower at high elevation. Although previous research concluded that the thermal physiology of P. tiliguerta is static, this study questions the strength of that claim, suggesting instead that decreased predation risk at high elevation may reduce the pressure to respond to the thermal environment. These data highlight that studies on lizard thermal ecology should consider a breadth of factors when evaluating adaptability.
