Effects of Ambient Light at Night on the Metabolic Rates of Anolis carolinensis

Novel changes to an organism's environment may pose physiological and ecological challenges. Ambient light at night (ALAN) acts as an environmental challenge in urban environments and might disrupt physiological functions of organisms such as the green anole (Anolis carolinensis). One physiological function that might be challenged by ALAN is metabolic rate which provides insight into the energy consumption of an organism. To test for impacts of ALAN on metabolic rates, a group of anoles were exposed to a 24:0 light:dark cycle (ALAN Treatment) while a separate group of anoles were placed under a 12:12 light:dark cycle (Control Treatment). Metabolic rates were tested over the span of six weeks at noon and midnight using low-range respirometry. The body condition of each anole was measured (i.e., a measure of health). ALAN metabolic rates were greater than Control metabolic rates halfway through the study (Week 3), but there was no difference in metabolic rates between treatments during the last week of the experiment (Week 6). Metabolic rates differed between noon and midnight during Week 1, but did not differ between noon and midnight during Week 3 or Week 6. Body condition did not differ between treatments throughout the entire study. Despite differences in metabolic rates during Week 3, ALAN anoles could have compensated for the environmental challenge by altering other life-characteristics. Following the principle of allocation, the anoles might have shunted energy toward bodily maintenance to compensate for the increased metabolic rates seen halfway through the study. Further, ALAN may not be a detrimental threat to anoles found in urban environments as they may be able to acclimate to this environmental challenge