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Sexual dimorphism in melanin pigmentation, feather coloration and its heritability in the barn swallow (Hirundo rustica).

Saino N, Romano M, Rubolini D, Teplitsky C, Ambrosini R, Caprioli M, Canova L, Wakamatsu K - PLoS ONE (2013)

Bottom Line: The relative concentration of either melanin (Pheo:Eu) differed between sexes in throat but not in belly feathers, and the concentrations in males compared to females were larger in belly than in throat feathers.Finally, we found high heritability of color of throat feathers.Melanization was found to differ from that recorded in Hirundo rustica rustica from Scotland or from H. r. erythrogaster from North America.

View Article: PubMed Central - PubMed

Affiliation: Department of Biosciences, University of Milan, Milan, Italy. nicola.saino@unimi.it

ABSTRACT
Melanin is the main pigment in animal coloration and considerable variation in the concentrations of the two melanin forms (pheo- and eumlanin) in pigmented tissues exists among populations and individuals. Melanin-based coloration is receiving increasing attention particularly in socio-sexual communication contexts because the melanocortin system has been hypothesized to provide a mechanistic basis for covariation between coloration and fitness traits. However, with few notable exceptions, little detailed information is available on inter-individual and inter-population variation in melanin pigmentation and on its environmental, genetic and ontogenetic components. Here, we investigate melanin-based coloration in an Italian population of a passerine bird, the barn swallow (Hirundo rustica rustica), its sex- and age-related variation, and heritability. The concentrations of eu- and pheomelanin in the throat (brown) and belly (white-to-brownish) feathers differed between sexes but not according to age. The relative concentration of either melanin (Pheo:Eu) differed between sexes in throat but not in belly feathers, and the concentrations in males compared to females were larger in belly than in throat feathers. There were weak correlations between the concentrations of melanins within as well as among plumage regions. Coloration of belly feathers was predicted by the concentration of both melanins whereas coloration of throat feathers was only predicted by pheomelanin in females. In addition, Pheo:Eu predicted coloration of throat feathers in females and that of belly feathers in males. Finally, we found high heritability of color of throat feathers. Melanization was found to differ from that recorded in Hirundo rustica rustica from Scotland or from H. r. erythrogaster from North America. Hence, present results show that pigmentation strategies vary in a complex manner according to sex and plumage region, and also among geographical populations, potentially reflecting adaptation to different natural and sexual selection regimes, and that some coloration components seem to be highly heritable.

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Related in: MedlinePlus

Relationships between ϑ and φ tetrahedral hue color components and eu- (PTCA) or pheomelanin (4-AHP).Panel A): throat feathers; panel B): belly feathers. Lines are fitted by linear regression to statistically significant relationships for either sex separately.
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pone-0058024-g004: Relationships between ϑ and φ tetrahedral hue color components and eu- (PTCA) or pheomelanin (4-AHP).Panel A): throat feathers; panel B): belly feathers. Lines are fitted by linear regression to statistically significant relationships for either sex separately.

Mentions: Within-sex there were poor associations between color components and melanin concentrations of throat feathers, with the exception of pheomelanin in females that was strongly associated with both the θ and φ color components (Table 3; Fig. 4a). In fact, a linear model disclosed a significant effect of the sex by pheomelanin concentration interaction on θ values (F1,41 = 4.15, P = 0.048) and a marginally non-significant effect on φ values (F1,41 = 3.58, P = 0.066), suggesting that the relationship between throat coloration and pheomelanin concentration differed between the sexes.


Sexual dimorphism in melanin pigmentation, feather coloration and its heritability in the barn swallow (Hirundo rustica).

Saino N, Romano M, Rubolini D, Teplitsky C, Ambrosini R, Caprioli M, Canova L, Wakamatsu K - PLoS ONE (2013)

Relationships between ϑ and φ tetrahedral hue color components and eu- (PTCA) or pheomelanin (4-AHP).Panel A): throat feathers; panel B): belly feathers. Lines are fitted by linear regression to statistically significant relationships for either sex separately.
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC3585210&req=5

pone-0058024-g004: Relationships between ϑ and φ tetrahedral hue color components and eu- (PTCA) or pheomelanin (4-AHP).Panel A): throat feathers; panel B): belly feathers. Lines are fitted by linear regression to statistically significant relationships for either sex separately.
Mentions: Within-sex there were poor associations between color components and melanin concentrations of throat feathers, with the exception of pheomelanin in females that was strongly associated with both the θ and φ color components (Table 3; Fig. 4a). In fact, a linear model disclosed a significant effect of the sex by pheomelanin concentration interaction on θ values (F1,41 = 4.15, P = 0.048) and a marginally non-significant effect on φ values (F1,41 = 3.58, P = 0.066), suggesting that the relationship between throat coloration and pheomelanin concentration differed between the sexes.

Bottom Line: The relative concentration of either melanin (Pheo:Eu) differed between sexes in throat but not in belly feathers, and the concentrations in males compared to females were larger in belly than in throat feathers.Finally, we found high heritability of color of throat feathers.Melanization was found to differ from that recorded in Hirundo rustica rustica from Scotland or from H. r. erythrogaster from North America.

View Article: PubMed Central - PubMed

Affiliation: Department of Biosciences, University of Milan, Milan, Italy. nicola.saino@unimi.it

ABSTRACT
Melanin is the main pigment in animal coloration and considerable variation in the concentrations of the two melanin forms (pheo- and eumlanin) in pigmented tissues exists among populations and individuals. Melanin-based coloration is receiving increasing attention particularly in socio-sexual communication contexts because the melanocortin system has been hypothesized to provide a mechanistic basis for covariation between coloration and fitness traits. However, with few notable exceptions, little detailed information is available on inter-individual and inter-population variation in melanin pigmentation and on its environmental, genetic and ontogenetic components. Here, we investigate melanin-based coloration in an Italian population of a passerine bird, the barn swallow (Hirundo rustica rustica), its sex- and age-related variation, and heritability. The concentrations of eu- and pheomelanin in the throat (brown) and belly (white-to-brownish) feathers differed between sexes but not according to age. The relative concentration of either melanin (Pheo:Eu) differed between sexes in throat but not in belly feathers, and the concentrations in males compared to females were larger in belly than in throat feathers. There were weak correlations between the concentrations of melanins within as well as among plumage regions. Coloration of belly feathers was predicted by the concentration of both melanins whereas coloration of throat feathers was only predicted by pheomelanin in females. In addition, Pheo:Eu predicted coloration of throat feathers in females and that of belly feathers in males. Finally, we found high heritability of color of throat feathers. Melanization was found to differ from that recorded in Hirundo rustica rustica from Scotland or from H. r. erythrogaster from North America. Hence, present results show that pigmentation strategies vary in a complex manner according to sex and plumage region, and also among geographical populations, potentially reflecting adaptation to different natural and sexual selection regimes, and that some coloration components seem to be highly heritable.

Show MeSH
Related in: MedlinePlus