Meeting Abstract
Introduced species are likely to rapidly adapt to local climates because of small founder populations and strong selective pressures in their new environments. Ectotherms may be particularly sensitive to climatic challenges, requiring swift adaptive change. To test these ideas, we compared thermal tolerances (critical thermal minimum, CTmin and panting threshold, Tpant) and temperature-dependent rates of evaporative water loss (EWL) and resting metabolism (RMR) of Mediterranean House Geckos (Hemidactylus turcicus) from different climates. These “porch light” geckos have been widely introduced throughout the New World since their first appearance in Florida in 1910. Eight populations of geckos were collected from the southern USA, representing three climates: desert (hot/dry; n = 2 populations), Mediterranean (warm/dry; n = 2), and subtropical (hot/humid; n = 4). We hypothesized that geckos would exhibit physiological differences consistent with adaptation to their local climates. Geckos from climates with cooler daytime temperatures had lower CTmin compared to those from hotter climates. However, we found no statistical difference in Tpant among populations. Compared to geckos from humid regions, those from arid climates had lower rates of EWL at higher temperatures, which is explained by correspondingly lower RMR. Interestingly, a recently founded (~3 yr) Mediterranean population did not show evidence of local adaptation. Future studies will include sprint performance and testing for developmental plasticity. Ultimately these data will be used in a mechanistic niche model to predict the future range expansion of this species in the USA.
