Carotenoid-based plumage colors and immune function: Is there a trade-off for rare carotenoids?

Fitze, Patrick; Tschirren, Barbara; Gasparini, Julien; Richner, Heinz (2007). Carotenoid-based plumage colors and immune function: Is there a trade-off for rare carotenoids? The American naturalist, 169(S1), S137-S144. Chicago, Ill.: University of Chicago Press 10.1086/510094

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Theory suggests that carotenoid-based signals are used in animal communication because they contain specific information about parasite resistance or immunocompetence. This implies that honesty of carotenoid-based signals is maintained by a trade-off between pigmentation and immune function for carotenoids, assuming that the carotenoids used for coloration are also immunoenhancing. We tested this hypothesis by altering the diets of nestling great tits (Paris major) with supplementary beadlets containing the carotenoids that are naturally ingested with food or beadlets containing the carotenoids that are incorporated into the feathers; a control group received beadlets containing no carotenoids. We simultaneously immune challenged half of the nestlings of each supplementation group, using a two-factorial design. Activatior of the immune system led to reduced color expression. However, only nestlings fed with the naturally ingested carotenoids and not with the carotenoids deposited in the feathers showed an increased cellular immune response. This shows that the carotenoids used for ornamentation do not promote the immune function, which conflicts with the trade-off hypothesis. Our results indicate that honesty of carotenoid-based signals is maintained by an individual's physiological limitation to absorb and/or transport carotenoids and by access to carotenoids, indicating that preferences for carotenoid-based traits in sexual selection or parent-offspring interactions select for competitive individuals, rather than specifically for immune function.

Item Type:	Journal Article (Original Article)
Division/Institute:	08 Faculty of Science > Department of Biology > Institute of Ecology and Evolution (IEE) > Evolutionary Ecology
UniBE Contributor:	Richner, Heinz
ISSN:	0003-0147
Publisher:	University of Chicago Press
Language:	English
Submitter:	Factscience Import
Date Deposited:	04 Oct 2013 14:58
Last Modified:	05 Dec 2022 14:18
Publisher DOI:	10.1086/510094
Web of Science ID:	000243526400010
URI:	https://boris.unibe.ch/id/eprint/24873 (FactScience: 53483)