Trends in Ecology & Evolution
ReviewStress and the evolution of condition-dependent signals
Section snippets
What do we mean by stress?
To examine the effects of physiological stress on the individual we need to understand what is meant by ‘stress’ (Box 1). For the individual, the stress response is typified by physiological changes to short- or long-term unpredictable alterations in environmental circumstances, which cause a redirection of resources to vital processes and impair, or threaten to impair, homeostasis1, 8. However, the stress response will vary enormously according to the nature of the stressor. A rapid-onset
Measuring stress
Individual stress levels can be assessed in a variety of ways. For example, invertebrate stress has been assessed extensively using levels of heat shock proteins (HSPs) (Box 2). By contrast, the most common method in vertebrate studies is to measure glucocorticoid production in relation to a standardized stressor (Box 3). Glucocorticoid production varies in relation to the intensity of the stressor and it is essential to focus upon biologically relevant levels of stress when examining the
Stress and immune function
The effects of stress upon the immune system are without doubt complex, variable and extremely controversial. The stress response is multifaceted in nature and, therefore, has the potential to affect immunocompetence through a variety of routes. Furthermore, immunocompetence involves allocation between different aspects of the immune system, which might be affected differentially.
This assessment is complicated further by the fact that the effects of glucocorticoids on the immune system differ
Stress and behavioural strategies
Individual differences in stress responses and the consequences for immune function open the possibility for a range of optimal behavioural strategies. Establishing and maintaining dominance rank involves potentially dangerous interactions, as social defeat can have important effects on individual physiology, which can last for periods of up to several days14. A long-term study of olive baboons (Papio anubis) has demonstrated differences in basal levels of glucocorticoids in relation to both an
Stress and condition-dependent signals?
According to the immunocompetence handicap hypothesis, immunosuppression by sex hormones mediates the cost of development of many secondary sexual signals30. The hypothesis predicts that levels of circulating androgens, necessary for the development of many sexual signals and behaviours, should covary with immune function31. Therefore, elaborate secondary sexual traits honestly reflect male quality by indicating the level of immune suppression an individual can tolerate. Although these
Prospects
Although the integration of physiological understanding with behavioural ecology is necessary if we are to understand the mechanisms underlying basic evolutionary processes, it must be done with care. Furthermore, it is necessary to be pragmatic about the difficulties of demonstrating the role of stress. Researchers should be aware of the potential pitfalls of generalizations concerning the physiology underlying exposure to stressful events. The stress response is complex and specific both to
Unlinked list
7, 9, 12, 27
Acknowledgements
I would like to thank Matthew Evans, Arthur Goldsmith, Kirsty Park, Ken Wilson, John Wingfield and two anonymous referees for their helpful comments on this article. K.L.B. is supported by NERC grant GR3/11426.
References (45)
Neuroendocrinology of the stress response
An Introduction to Neuroendocrinology
(1994)On the adaptive significance of stress-induced immunosuppression
Proc. R. Soc. London Ser. B
(1998)Nestling diet, secondary sexual traits and fitness in the zebra finch
Proc. R. Soc. London Ser. B
(1999)Good genes, oxidative stress and condition-dependent sexual signals
Proc. R. Soc. London Ser. B
(1999)- et al.
Stress and Animal Welfare
(1993) Evolutionary rates: stress and species boundaries
Annu. Rev. Ecol. Syst.
(1991)Corticosterone and behavioural responses to unpredictable events
Modulation of the adrenocortical response to stress in birds
Does stress damage the brain?
Biol. Psychiatry
(1999)
Stress and cognition: are corticosteroids good or bad guys?
Trends Neurosci
Progress and perspectives in the biology of heatshock proteins and molecular chaperones
Sexual selection in the zebra finch Taeniopygia guttata: condition, sex traits and immune capacity
Behav. Ecol. Sociobiol.
The temporal dynamics of the stress response
Neurosci. Biobehav. Rev.
Physiological effects of hunting red deer (Cervus elaphus)
Proc. R. Soc. London Ser. B
Increase in a heat-shock protein from blood cells in response of nestling house martins (Delichon urbica) to parasitism: an experimental approach
Oecologia
Gene therapy with HSP72 is neuroprotective in rat models of stroke and epilepsy
Ann. Neurol.
Stress and cognitive function
Curr. Opin. Neurobiol.
Endocrine regulation of host immunity
Parasite-mediated sexual selection: endocrine aspects
The integration of the neuroendocrine and immune systems: a marriage of convenience or necessity?
Physiological functions of glucocorticosteroids in stress and their relation to pharmacological actions
Endocr. Rev.
Cited by (307)
Heat stress reveals a fertility debt owing to postcopulatory sexual selection
2024, Evolution LettersDIESL fuels a DGAT-independent triglyceride synthesis pathway
2023, Life MetabolismBarley shows reduced Fusarium head blight under drought and modular expression of differentially expressed genes under combined stress
2023, Journal of Experimental BotanyComparison between the gut bacterial community of laboratory cultured and wild Daphnia
2023, FEMS Microbiology Ecology