Integrating Physiology and Behavior in Assessment of Ectotherm Heat Tolerance

Understanding thermal performance and upper thermal limits of ectothermic organisms is crucial for predicting species responses to climate change. Traditionally, growth and fitness are described by thermal performance curves (TPC), showing sensitivity of life across permissive temperatures. Above a critical limit (Tc), injury accumulates until death, modeled by the thermal death time (TDT) approach. However, in nature, fluctuating temperatures expose animals to cycles of stress and repair, highlighting the need to integrate life and death models for better climate predictions.

Although many studies have discussed how thermal limits should be measured, interpreted, and applied, there are still many unknowns of how to integrate the physiological causes of heat stress in this understanding across permissive and stressful exposures. Further the roles of exposure time, acclimation, behaviour, and microhabitat selection remains challenging to integrate in models of thermal sensitivity.

This workshop will unite leading thermal-ecologists, physiologists, and modelers to advance knowledge of thermal stress biology in ectotherms and establish a unified framework for analysing consequences of high-temperature stress. Specifically we will:

• Discuss the utility of CTmax, TPC, and TDT in assessing climate sensitivity and linking these measures to heat stress physiology
• Discuss how models could consider fluctuating exposure to sublethal stress and how to include adaptation, acclimation, and hardening
• Discuss tools for aligning operative temperature of field exposure to heat stress assessment based on lab-based sensitivity estimates