The role of testosterone in bib size determination in the male house sparrow Passer domesticus, is age dependent

Roberts, Mark L., Buchanan, Katherine L., Goldsmith, Arthur R. and Evans, Matthew R. 2012, The role of testosterone in bib size determination in the male house sparrow Passer domesticus, is age dependent, Journal of avian biology, vol. 43, no. 3, pp. 264-272.

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Title The role of testosterone in bib size determination in the male house sparrow Passer domesticus, is age dependent
Formatted title The role of testosterone in bib size determination in the male house sparrow Passer domesticus, is age dependent
Author(s) Roberts, Mark L.
Buchanan, Katherine L.
Goldsmith, Arthur R.
Evans, Matthew R.
Journal name Journal of avian biology
Volume number 43
Issue number 3
Start page 264
End page 272
Total pages 9
Publisher Wiley - Blackwell Publishing
Place of publication Malden, Mass.
Publication date 2012-05
ISSN 0908-8857
1600-048X
Keyword(s) adaptation
age
gene expression
immune response
juvenile
passerine
sexual selection
signaling
testosterone
Summary Secondary sexual signals are thought to indicate individual quality. In order to understand the evolutionary pressures that give rise to such traits it is important to understand the physiological mechanisms underlying their production. The black bib of the house sparrow Passer domesticus is known to function as a badge of social status in males. Past studies have found that the size of the bib in older males is determined, at least partly, by the androgen testosterone. The immunocompetence handicap hypothesis suggests that testosterone has a key role in maintaining honest signalling – it is both involved in the development or expression of sexual signals and is immunosuppressive. In this paper we test experimentally two hypo theses relating to bib size development, whether 1) testosterone is only immunosuppressive in conditions where the natural feedback loop from the testes has been removed, and 2) testosterone is, in addition to influencing the bib size of older males, responsible for the size of the bib in juvenile sparrows. In the first experiment we found that exogenous testosterone administered to intact males during the winter (when LH and FSH levels are very low and were not artificially increased by castration) caused significant immunosuppression, albeit in interaction with the stress hormone corticosterone. Second, we found that exogenous testosterone administration in castrated fledgling male house sparrows had no effect on subsequent post-juvenile moult bib size relative to controls. Our results suggest that in some circumstances testosterone can be immunosuppressive, but that its role in bib size determination is age-dependent.
Language eng
Field of Research 069999 Biological Sciences not elsewhere classified
Socio Economic Objective 970106 Expanding Knowledge in the Biological Sciences
HERDC Research category C1 Refereed article in a scholarly journal
Copyright notice ©2012, The Authors. Journal of Avian Biology. 2012 Nordic Society Oikos
Persistent URL http://hdl.handle.net/10536/DRO/DU:30047027

Document type: Journal Article
Collection: School of Life and Environmental Sciences
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