Thermal Ecology and Thermoregulatory Behavior of the Invasive Turtle, Trachemys scripta elegans, in the Mediterranean...

The success of invasive species, which pose a significant threat to global biodiversity, hinges on their physiological and ecological adaptive capacities to the environments into which they are introduced. Trachemys scripta elegans (T. scripta elegans), recognized as one of the world's 100 most invasive species, has spread across a wide geographic range and exerts considerable pressure on native ecosystems. To investigate this, we studied the thermal ecology of an invasive population of T. scripta elegans in a wetland located in the province of Manisa, in Western Anatolia. Our objective was to assess the species' level of pre-adaptation to local climatic and habitat conditions and to identify its thermoregulatory strategies. Between March and October 2024, we measured individual body temperatures (T_b) and environmental temperatures (T_e) in the study area; concurrently, we recorded data on water temperature (T_w), air temperature (T_a), solar radiation intensity, and wind speed. We also measured preffered body temperatures (T_set) in the laboratory. We found that the thermal quality of the habitat (d_e) was suboptimal during the species' primary activity period, thereby presenting a thermally challenging environment. Despite this, the invading population exhibited high thermoregulatory accuracy (d_b), successfully maintaining its body temperatures in close alignment with its preferred temperature range. This resulted in a high index of thermoregulatory effectiveness (E = 0.79) and a positive thermoregulation index value (I = 3.79 > 0). Furthermore, Pearson correlation analysis revealed a strong positive correlation between T_b and T_w, as well as between T_b and T_a. Our results indicate that the invasive T. scripta elegans population prefers an effective thermoregulation option rather than being thermoconformist. This high thermoregulatory capability represents a key pre-adaptation, enabling the species to spread successfully even in thermally suboptimal habitats and providing a competitive advantage over native species. The findings from our study support projections that in the face of a warming climate, thermal stress tolerance and behavioral thermoregulation can facilitate the expansion of invasive species.