Artificial Light at Night Disrupts Circadian and Metabolic Gene Expression in the Green Anole Lizard ( Anolis carolinensis ): A Transcriptomic Analysis

Artificial light at night (ALAN) disrupts natural light-dark cycles, posing ecological challenges for wildlife in urban areas. Here we investigated the effects of ALAN on gene expression in the brain, liver, and skin of green anole lizards ( Anolis carolinensis ) whose urban populations are increasingly exposed to light pollution. To identify genetic pathways impacted by ALAN exposure we analysed expression of genes associated with circadian and metabolic regulation at midday, midnight and at midnight with artificial light. Differential expression analysis revealed that clock-related genes ( PER1 , NR1D1 , CRY2 ) were significantly altered in the brain, liver, and skin following ALAN treatment and genes involved in glucagon regulation ( GCG ) and lipid metabolism ( NOCT ) were differentially expressed in the liver, indicating metabolic disruptions. Skin exhibited unique responses to ALAN suggesting that repair responses may be altered as genes related to cellular processes, such as wound healing, were upregulated under normal light and dark conditions. Our findings also show that ALAN disrupts core circadian genes, impacting physiological processes including hormone regulation, glucose homeostasis, and potentially reproductive cycles. This study provides the first transcriptomic evidence of the effects of light pollution on green anoles, highlighting the need to preserve natural light cycles in urban habitats. An interactive online database developed for this study allows further exploration of gene expression changes, to promote research on artificial light-polluted environments.