Meeting Abstract
In response to global climate change, organisms can move, adapt, acclimate, or die. Ectotherms are at particular risk to the effects of climate change because they behaviorally thermoregulate instead of creating heat through metabolic processes, and many cannot migrate to suitable conditions due to environmental or physiological barriers. The fence lizard Sceloporus consobrinus is a well-studied organism whose embryos have been shown to acclimate to temperature differences during development, but these studies have been conducted using constant temperature states. It is unclear whether embryos will respond similarly to fluctuating temperatures that naturally occur daily and seasonally. To assess the effect of fluctuating temperature on S. consobrinus embryos, we split clutches from 30 females and incubated eggs under two fluctuating conditions. The first fluctuated between 24 and 34˚C (average 27˚C). The second treatment fluctuated between 24 and 38˚C (average 30˚C). After 30 ± 4.6% of the incubation period in each treatment we measured embryonic heart rate at 33˚C (which is near the optimum for performance for juvenile and adult lizards). We chose our thermal treatments to simulate the average current conditions experienced by embryos and a condition with high temperature fluctuations, to simulate what animals might experience in the future. Contrary to the previous study conducted using constant incubation conditions, we found no difference in heart rates between the two treatments, suggesting that S. consobrinus embryos do not acclimate to their environments during development. As suggested previously by many authors, inferences about physiological variation can be sensitive to experimental conditions. Researchers should strive to simulate natural environmental variation when assessing physiological responses to the environment.
