Development under artificial light at night (ALAN) alters telomere dynamics in a nocturnal amphibian

Artificial light at night (ALAN) is a rapidly increasing global threat to wildlife, disrupting circadian rhythms and inducing physiological costs such as oxidative stress. However, the underlying mechanisms are still poorly understood. Telomeres, the protective caps of DNA, are biomarkers for somatic condition and aging, as they are sensitive to environmental stressors. In this study, we investigated the effects of ALAN on the telomere length of developing European green toads (Bufotes viridis). Our results show that individuals developing under ALAN had longer telomeres and a non-significant trend toward increased mortality. Metamorphs showed a trend towards longer telomeres in both the experimental and the control group. These findings suggest that accelerated telomere loss, likely caused by higher levels of oxidative stress under ALAN, may lead to compensatory antioxidative defence and telomere restoration mechanisms. However, possible long-term costs and accumulating effects like an increased cancer risk associated with longer telomeres, should be considered. In this study we show that ALAN significantly alters telomere dynamics in the European green toad, highlighting the importance for further studies on the consequences of increasing ALAN on wildlife.