Physiological stress links parasites to carotenoid-based colour signals

• Published in: Journal of evolutionary biology Vol. 23; no. 3; pp. 643 - 650
• Main Authors: MOUGEOT, F, MARTÍNEZ-PADILLA, J, BORTOLOTTI, G.R, WEBSTER, L.M.I, PIERTNEY, S.B
• Format: Journal Article
• Language: English
• Published: Oxford, UK Oxford, UK : Blackwell Publishing Ltd 01-03-2010; Blackwell Publishing Ltd
• Subjects: Animals; Anthelmintics; Birds; Body mass; Body Weight; Carotenoids; Carotenoids - blood; Color; Coloration; Corticosterone; Corticosterone - metabolism; Diets; Evolutionary biology; feather corticosterone; Feathers - metabolism; Galliformes - blood; Galliformes - parasitology; Host-Pathogen Interactions; Infection; Lagopus lagopus scoticus; Male; Nematoda; nematode parasite; Nematodes; Nutritional status; Parasites; Pigmentation; red grouse Lagopus lagopus scoticus; sexual selection; signal evolution; Stress; Stress, Physiological; trade-off; Trichostrongylus - physiology; Trichostrongylus tenuis
• ISSN: 1010-061X; 1420-9101
• DOI: 10.1111/j.1420-9101.2009.01926.x

Vertebrates commonly use carotenoid-based traits as social signals. These can reliably advertise current nutritional status and health because carotenoids must be acquired through the diet and their allocation to ornaments is traded-off against other self-maintenance needs. We propose that the coloration more generally reveals an individual's ability to cope with stressful conditions. We tested this idea by manipulating the nematode parasite infection in free-living red grouse (Lagopus lagopus scoticus) and examining the effects on body mass, carotenoid-based coloration of a main social signal and the amount of corticosterone deposited in feathers grown during the experiment. We show that parasites increase stress and reduce carotenoid-based coloration, and that the impact of parasites on coloration was associated with changes in corticosterone, more than changes in body mass. Carotenoid-based coloration appears linked to physiological stress and could therefore reveal an individual's ability to cope with stressors.