Carotenoid plasma concentration, immune profile, and plumage ornamentationof male barn swallows (Hirundo rustica)

Citation
N. Saino et al., Carotenoid plasma concentration, immune profile, and plumage ornamentationof male barn swallows (Hirundo rustica), AM NATURAL, 154(4), 1999, pp. 441-448
Citations number
48
Language
INGLESE
art.tipo
Article
Categorie Soggetti
Environment/Ecology
Journal title
AMERICAN NATURALIST
ISSN journal
0003-0147 → ACNP
Volume
154
Issue
4
Year of publication
1999
Pages
441 - 448
Database
ISI
SICI code
0003-0147(199910)154:4<441:CPCIPA>2.0.ZU;2-W
Abstract
Carotenoids exert immunomodulating, immunostimulating, and antioxidant acti ons in mammals and are major determinants of coloration in animals. Honest advertisement models of sexual selection propose that male ornaments, inclu ding coloration, are reliable indicators of male quality. Because of their simultaneous effects on male coloration and immunity, carotenoids might med iate the hypothesized relationship between the expression of epigamic color ation and parasitism in vertebrates. We analyzed the relationship between i mmune profile and concentration of lutein, the most abundant carotenoid in the plasma of male barn swallows (Hirundo rustica). Consistent with our pre dictions, lutein plasma concentration was negatively correlated with gamma- globulin plasma levels and concentration of selected leukocyte types in per ipheral blood, suggesting that, to exert immune function, carotenoids are t aken up from plasma, thus becoming unavailable for epigamic signaling. The coloration of red feathers of the throat of adult males was positively rela ted to plasma concentration of lutein, but not with immunologic variables, consistent with the idea that more brightly colored males do not pay a larg er immunological cost for their cole ration compared with less brightly col ored males. Length of male rail ornaments, which is currently under directi onal sexual selection, was positively correlated with lutein plasma levels. In species where carotenoids limit immune function, demands for pigments f or sexual signaling might compete with those for immunity, thus generating a mechanism that enforces honesty on the signal.