Meeting Abstract
Thermal tolerance data are collected to increase our understanding of how closely an organism’s physiology reflects adaptation to its environment. Unfortunately, because thermal tolerance can be highly plastic, sensitive to prior housing conditions, and sensitive to methods of measurement, comparisons between and within studies can be complicated. Though we know that thermal tolerance is plastic, to understand how it relates to adaptation to the thermal environment, it is important to study how plastic it can be. To do this, we measured cold tolerance of two non-native populations of Podarcis siculus once weekly during a cold acclimation treatment. Heat tolerance, thermal preference, evaporative water loss, and standard metabolic rate were also measured before and after the cold acclimation treatment. We found that the population of P. siculus from the more variable climate (Long Island, NY) was able to shift its cold tolerance relatively quickly, whereas the population from the milder climate (San Pedro, CA) did not shift its cold tolerance. NY lizards also decreased thermal preference while CA lizards did not. Temperature coefficients (Q10 ) of water loss and metabolism were greater in CA lizards. Overall, results suggest that NY lizards are more adapted to a varying thermal climate compared to CA lizards. This underlying difference in plasticity, a potentially adaptive trait, would not have been detected if lizards had only been tested once prior to the cold acclimation treatment. These findings highlight the need to incorporate plasticity into theory and experiments investigating potentially adaptive traits.
