Artificial light at night (ALAN) is an omnipresent anthropogenic stressor disrupting ecological interactions, potentially driving rapid evolutionary change. However, evidence for genetic adaptation to ALAN remains limited, with ecological responses dominating observed effects. Here, we critically review current evidence for evolution under ALAN and propose that interactions between ecological and evolutionary processes—so-called eco-evolutionary feedbacks—may obscure direct evolutionary signals. We argue for more common-garden experiments to disentangle genetic adaptation from environmentally induced plasticity, for multiple study organisms. Using a conceptual framework of an urban freshwater pond and a key ecological interactor, the water flea Daphnia, we illustrate how ALAN may affect key ecological phenomena, including diel vertical migration, parasite infection, and top-down control of algae, and may impose complex and cascading selection pressures. Recognizing interactions between ecological and evolutionary processes provides new insights on how light pollution can influence ecosystem health and inform conservation strategies in increasingly illuminated environments.
