Thermal Preference Plasticity in Ectotherms: Integrating Temperature Affinity and Thermoregulation Precision

AbstractThermal preference (Tp) prevents ectotherms from encountering sublethal temperatures. Its plasticity likely modulates the importance of behavioral thermoregulation under changing conditions. While it has been widely recognized that Tp varies across ontogeny, the plasticity level of this trait across life stages is poorly understood. We propose a novel conceptual framework relating two plastic components of Tp: its mean, which indicates temperature affinity, and its variance, which informs on the precision of behavioral thermoregulation. We tested this framework at the population scale by measuring Tp variations across life stages of an insect model after several generations under contrasting developmental temperatures. Tp plastic responses differed among life stages. Generally, we obtained a bell-shaped relationship between temperature affinity and precision of thermoregulation, indicating a strategy to avoid suboptimal and supraoptimal temperatures in Drosophila melanogaster, but not in all life stages. We highlight the need to change the paradigm underlying the study of Tp plasticity beyond the use of a single metric (median or range) to better comprehend thermoregulatory strategies.