Showiness, Carotenoids, and Captivity: A Comment on Hill (1992)

Hudon, Jocelyn

doi:10.2307/4088529

Cited by 110 publications

(73 citation statements)

References 21 publications

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“…Bright colours may be sexually selected traits that operate as social signals (Lozano 1994;Gray 1996). Such a function depends on pigments, or colour expression, being costly or at least limited to only some individuals; however, to date there has been little consensus, and fewer empirical data, as to whether or not carotenoids are a scarce resource (Hudon 1994;Olson & Owens 1998;Grether et al 1999).…”

Section: Introductionmentioning

confidence: 99%

“…There is abundant indirect evidence of the importance of dietary concentrations of carotenoids in determining coloration or plasma carotenoids in wild birds (Slagsvold & Lifjeld 1985;Linville & Brietwisch 1997;Eeva et al 1998;Negro et al 2000). However, it does not follow that dietary e¡ects also prove that carotenoids in the environment are limited (Hudon 1994). Only Grether et al (1999) have shown that carotenoid availability in the wild limits the expression of colour in animals, in this case guppies (Poecilia reticulata).…”

Section: Introductionmentioning

confidence: 99%

“…In addition to the issue of environmental availability, limitation may occur post-consumption and be inherent in an individual's physiological need or ability to absorb and use carotenoids Hudon 1994). Physiological demands are expected to vary in part because of an individual's genetic make-up.…”

Section: Introductionmentioning

confidence: 99%

“…In addition to the availability of this background work on variation in carotenoids of captive birds, kestrels are a good model for investigating carotenoid availability given their diet. Many studies of carotenoid-based coloration have been conducted on granivores and frugivores Gray 1996;Linville & Brietwisch 1997), which may have an abundance of carotenoids in their diet (Hudon 1994;Grether et al 1999). As carnivores, kestrels are predicted to have di¤culty in acquiring carotenoids (Gray 1996;Olson & Owens 1998;Hill 1999).…”

Section: Introductionmentioning

confidence: 99%

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Genetics, local environment and health as factors influencing plasma carotenoids in wild American kestrels (Falco sparverius)

Bortolotti

Tella

Forero

et al. 2000

Proc. R. Soc. Lond. B

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Carotenoids are important as pigments for bright coloration of animals, and as physiologically active compounds with a wide array of health-related functions. Carotenoid-dependent coloration may have evolved as a signal to conspeci¢cs; however, factors that may limit availability of carotenoids are poorly known. We investigated how the acquisition of carotenoids may be constrained by availability in the environment, diet, genetic make-up and health status of wild American kestrels (Falco sparverius). Plasma concentrations of siblings at the time of £edging showed a high degree of resemblance; however, a crossfostering experiment revealed that variance was largely explained by nest of rearing, rather than nest of origin, thus indicating a low genetic component. A multivariate analysis of attributes of nestlings (sex, size, plasma proteins, immune function), parental reproduction (laying date, clutch size) and rearing conditions (brood size, size hierarchy, nestling mortality) showed only a small signi¢cant e¡ect of leucocyte di¡erentials on carotenoid concentrations of nestlings. A strong environmental e¡ect on plasma carotenoids was demonstrated by levels of adult kestrels being correlated within mated pairs, and having a signi¢cant association with the abundance of voles, the primary prey species, per territory.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Genetics, local environment and health as factors influencing plasma carotenoids in wild American kestrels (Falco sparverius)

Bortolotti

Tella

Forero

et al. 2000

Proc. R. Soc. Lond. B

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“…These compounds are responsible for most bright reds and yellows in vertebrates (Brush 1990), but they also are important physiological modulators and so have a range of health-related functions (Lozano 1994;Rock, Jacob & Bowen 1996). A number of studies of birds (Zuk et al 1990;Hill & Montgomerie 1994;Hudon 1994;Dufva & Allander 1995;Sundberg 1995) …”

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confidence: 99%

Regulation of integumentary colour and plasma carotenoids in American Kestrels consistent with sexual selection theory

et al. 1998

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(1871) proposed the theory of sexual selection, whereby the choice of mates by females could result in the evolution of elaborate secondary sex traits. Various patterns in nature suggested sexual selection to Darwin. He proposed that when morphological characters were sexually dimorphic, developed in males only at sexual maturity, and appeared during the breeding season, then such traits functioned to enhance a male's chance of reproducing (see Andersson 1994). While recent research has contributed considerably to the development of sexual selection theory, empirical studies of physiological mechanisms responsible for the expression and development of the selected traits have lagged behind (see Cronin 1991; Andersson 1994).The evolution of bright coloration in male birds has been a frequent, albeit controversial, topic since Darwin's time (Cronin 1991). Of particular recent interest has been the role of carotenoid pigments in sexual selection. These compounds are responsible for most bright reds and yellows in vertebrates (Brush 1990), but they also are important physiological modulators and so have a range of health-related functions (Lozano 1994;Rock, Jacob & Bowen 1996). A number of studies of birds (Zuk et al. 1990;Hill & Montgomerie 1994;Hudon 1994;Dufva & Allander 1995;Sundberg 1995) Summary1. Sexually selected traits are expected to vary seasonally, with the maximal expression of the character being evident during mate choice; however, the mechanisms controlling or regulating such traits are generally poorly known. 2. Carotenoid pigments responsible for bright red or yellow coloration in the feathers, skin or other integumentary structures of birds are generally believed to vary seasonally because of diet. 3. Variation in carotenoid-dependent skin colour between winter and spring (mating season) was investigated, as was variation in plasma carotenoids across the breeding season in captive American Kestrels, Falco sparverius, fed a uniform diet. 4. Kestrels were more brightly coloured in the mating period than in winter, and plasma carotenoid concentrations declined from the time of mating to the rearing of young. 5. Although carotenoid levels were highly sexually dimorphic during mating and laying, males and both breeding and non-breeding females all had similar levels by the incubation period, and the pattern of variation over time suggests rheostatic regulation. 6. These results suggest kestrels may have the ability to regulate (rather than merely control) their colour physiologically, the variation in colour and carotenoids is consistent with that expected of a sexually selected trait, and the loss of colour after breeding may suggest a trade-off between the show and health functions of carotenoids.

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