Physiological stress links parasites to carotenoid-based colour signals.
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.
Mougeot
F
F
EEZA (CSIC), Almeria, Spain. francois.mougeot@eeza.csic.es
Martínez-Padilla
J
J
Bortolotti
G R
GR
Webster
L M I
LM
Piertney
S B
SB
D000818:Animals; D000871:Anthelmintics; D001835:Body Weight; D002338:Carotenoids / Q000097:blood*; D003345:Corticosterone / Q000378:metabolism; D005241:Feathers / Q000378:metabolism; D046094:Galliformes / Q000097:blood / Q000469:parasitology*; D054884:Host-Pathogen Interactions; D008297:Male; D010858:Pigmentation; D013312:Stress, Physiological; D014254:Trichostrongylus / Q000502:physiology*
D000871:Anthelmintics; D002338:Carotenoids; D003345:Corticosterone