Graduate Research and Discovery Symposium (GRADS)

Document Type


Publication Date

Spring 2015


Sublethal stressors will likely mediate an organism’s response to climate change. Mobile animals can change their behavior to maintain temperatures within preferred ranges. However, animals in immobile life stages are particularly vulnerable to warming. For example, lizard embryos experience recurrent thermal stress as they develop in shallow nests with daily temperature fluctuations. Nesting temperatures above 41.5°C can be lethal to Eastern fence lizard (Sceloporus undulatus) embryos. Although that is beyond the range experienced at current nest sites, rapid warming will push nest conditions toward critical limits. Therefore, it is important to examine the effects of sublethal high nest temperatures on developing lizards. We reared S. undulatus embryos under three thermal regimes—one to simulate contemporary nest conditions with a maximum daily temperature (Tmax) of 32.1°C, and two regimes to simulate warming scenarios in which the Tmax was raised to 35.6°C and 39.1°C. We tracked changes in physiology and survival through embryonic development, and we measured growth and metabolic rates of surviving hatchlings. Results showed reduced embryo survival and decreased hatchling growth for lizards reared under sublethal warming, suggesting that thermal constraints on the physiology of developing Eastern fence lizards may limit the persistence of the species under climate warming.