Stress and the evolution of condition-dependent signals.

Stressful events are known to initiate a cascade of physiological mechanisms that are potentially costly for metabolic processes. Although these mechanisms are well understood, the long-term costs and the potential implications for individual condition and behaviour have been considered only recently. Combining information from physiological, ecological and behavioural studies can help us to understand the implications of stress for individual life history strategies. Furthermore, the concept of individual variation in stress tolerance has implications for the immunocompetence handicap hypothesis and the evolution of secondary sexual signals.