Impact of food availability on the thermal performance curves of male European green lizards (Lacerta viridis)

In a changing environment, characterized by human-induced rapid environmental change (HIREC), understanding the impacts of environmental stressors on reptile species is crucial. Preferred body temperatures (PBT) and thermal performance curves (TPCs) are comprehensive thermal physiology traits reflecting overall physiological performance and crucial for predicting species-specific responses to environmental changes. There is limited or conflicting information on how food availability affect the PBT and TPCs of lizard species, despite their significance in the context of the global decline in reptile species. The aim of this study was to experimentally investigate how food deprivation affects the PBT and TPCs of the European green lizards (Lacerta viridis). We exposed 30 adult male European green lizards to optimal and suboptimal food treatments. We assessed PBTs, and characterized the TPCs based on the thermal optimum (T_o), the maximum performance (P_max) and performance breadth (B₈₀) of the lizards. We found that food availability had a significant impact on preferred body temperature and locomotor performance. Lizards experiencing suboptimal conditions showed a preference for lower body temperatures, indicating an intention to minimize energy expenditure during fasting. Additionally, food-deprived lizards had wider B₈₀ range, suggesting their thermal acclimatization to maintain effective performance across a broader temperature range. Our findings highlight the importance of food availability as a key environmental stressor influencing thermoregulation strategies. As habitat modifications and global warming continue, it is crucial to evaluate the impacts of these changes on species for the development of effective conservation strategies.