From thermoregulation to photoregulation: Ultraviolet radiation exposure is regulated by lizard behaviours

Research Highlight: Lattanzio, M. S. (2026). Beyond thermoregulation: Active behavioural regulation of ultraviolet light exposure by a free-ranging lizard. Journal of Animal Ecology, https://doi.org/10.1111/1365-2656.70321. Exposure to ultraviolet radiation (UV) is both inevitable to any diurnal organism and a biological necessity for many animals. In many vertebrates, including lizards, UV exposure prompts important biological processes such as the endogenous production of vitamin D₃. Overexposure, however, can damage DNA, cells and tissues. Despite an extensive literature on how heliothermic lizards regulate body temperatures in heterogeneous environments by moving between areas with different levels of sun exposure, very little attention has been given to how these organisms might also regulate UV exposure. In a study combining laboratory experiments to assess preferred body temperatures and levels of UV exposure and field observations of lizards in contrasting environments, Lattanzio (2026) demonstrates that ornate tree lizards (Urosaurus ornatus) are capable of effectively maintaining preferred body temperatures in environments with and without plentiful shade access. At the same time, lizards could effectively regulate their levels of UV exposure in environments with shade, but were poor at doing so on tree snags without sufficient cover. This suggests that lizards may suffer consequences, either due to the physiological impacts of overexposure to UV or due to behavioural trade-offs, in these environments. Establishing the ecological relevance of UV exposure to lizard physiology, behaviours and life-histories provides direction to exciting new research avenues, expanding the field of lizard thermoregulation to additional axes of environmental variation.