Meeting Abstract
Organismal responses to rapid climate change rely heavily on the plasticity of physiology and behavior. For instance, mobile animals can behaviorally thermoregulate to buffer effects of climate warming. Yet, animals in immobile life stages lack the capacity to alter behavior and therefore rely on physiology. When a female Eastern fence lizard (Sceloporus undulatus) chooses a nest site, she determines the conditions experienced by her embryos. Developing embryos are exposed to recurrent thermal stress in shallow nests with fluctuating temperatures. In Summer 2014, we conducted a laboratory experiment to evaluate the capacity for acclimation to the embryonic thermal environment. We reared S. undulatus embryos under three thermal regimes—a contemporary regime with a maximum daily temperature (Tmax) of 32.1°C, and two regimes to simulate warming scenarios in which Tmax was raised by 3.5°C and 7.0°C. Results showed embryos from warmer nests had lower survivorship and grew more slowly post-hatching. In Summer 2015, we conducted a field experiment on S. undulatus nests located using radio telemetry of gravid females. We experimentally warmed a random subset of the nests, then compared embryonic survival and hatchling phenotypes to that of the remaining unaltered nests. Results showed similar effects to the lab study: offspring from warmed nests survived less and grew more slowly. The lab results indicate that increased nest mortality and thermal constraints on the physiology of developing lizards may limit the persistence of the species under climate change. However, our field results suggest that existing variation in nest characteristics and nest site selection might buffer offspring to a changing environment.
