An evolutionary perspective on stress responses, damage and repair

Area of Science:

• Evolutionary biology
• Physiological ecology
• Stress physiology

Background:

• Stress responses vary with environment, ecology, life history, and fitness.
• Mechanistic studies reveal how stress causes physiological damage and repair.
• The influence of damage and repair on stress response evolution remains unclear.

Purpose of the Study:

• To investigate the evolution of hormone levels considering stressor occurrence, damage, and repair efficiency.
• To model how fitness consequences of damage and repair influence stress response evolution.
• To understand optimal stress response strategies under varying stressor dynamics.

Main Methods:

• A simplified model of repeated stressor encounters with varying frequency and predictability.
• Analysis of optimal strategies for hormone levels (stress response).
• Investigation of strategy responses to acute and chronic stressor exposures.

Main Results:

• Higher repair rates lead to elevated baseline and peak hormone levels, increasing damage that is quickly repaired.
• Increased stressor predictability results in sustained stress responses and potential damage buildup.
• Chronic stressor exposure can lead to fatal damage levels if organisms are not evolutionarily adapted.

Conclusions:

• Stress response evolution is shaped by the interplay of stressor dynamics, damage, and repair.
• Optimal stress responses depend on the balance between stressor risk and damage-induced risk.
• Understanding stress physiology evolution requires joint consideration of stressor timing, mortality risks, and repair efficiency.