As I’m sure we are all aware, humans are causing a lot of significant changes to their surrounding environments. These changes can include habitat loss or fragmentation or urbanization just to name a few. However, one novel component of anthropogenic change is the introduction of artificial light into ecosystems that were otherwise dark. Artificial light at night (ALAN) is a new pressure that many organisms haven’t necessarily dealt with before humans rose to industrial fame. The impacts of ALAN on species across the globe is something more people are realizing can be severe and harmful to populations of wild animals. ALAN is capable of altering many important ecological factors for species, including their susceptibility to predation, access to food, sleep, hormones, and reproduction.

Chris Thawley, an NSF postdoctoral researcher in the lab of Jason Kolbe at the University of Rhode Island, devised a field experiment to test for the impacts of ALAN on brown anoles (Anolis sagrei) from southern Florida. Previously, Thawley and colleagues found in the lab that ALAN increases growth in female brown anoles and causes them to initiate egg-laying earlier, thereby increasing their reproductive output. But in this study, they aimed to quantify how ALAN affects anoles in the field, to further ground-truth their laboratory results.

Thawley and colleagues traveled to southern Florida, marked over 200 individual brown anoles with individual beads, and monitored their sensitivity and orientation to ALAN. They found that anoles are exposed to a significant amount of ALAN at their sleeping perches, but that anoles didn’t necessarily exhibit behavioral avoidance of ALAN. They also performed physiological analyses and found that ALAN reduced plasma glucose (a good proxy for energy availability) in the bloodstream of these lizards by approximately 10%, a huge energetic cost for these lizards. Thawley and colleagues plan to continue adding individual lizards to their already impressive dataset to provide a holistic story, including ecological, behavioral, physiological costs of ALAN on these brown anoles. Stay tuned!!

Anthony Gilbert
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