Abstract

LOPEZ, Aldana S  and  FERRETTI, Valentina. Plumage coloration in museum specimens of White-rumped swallow (Tachycineta leucorrhoa). Hornero [online]. 2018, vol.33, n.1, pp.19-28. ISSN 0073-3407.

The genus Tachycineta includes nine species of swallows distributed throughout the Americas with large differences in their genetic mating systems and extra-pair paternity rates. A previous study found 78% of White-rumped Swallow (Tachycineta leucorrhoa) nests could have at least one extra-pair nestling, with a variation of 1-4 different male sires for their nestlings. Given that extra-pair paternity can be an indicator of the intensity of sexual selection, we evaluated the sexual dimorphism of this species, as a brighter or striking coloration in males could be used by females as a quality signal to be preferred when choosing a mating partner. We measured spectral reflectance at 90° and 45° in four body regions in museum specimens. We found curves with peaks at wavelengths within the blue and white, associated with the coloration observed in the plumage. We did not find differences between males and females in hue, mean brightness, UV chroma, violet, blue or green in any of the body regions. Lack of sexual dimorphism may be caused by plumage not being an indicator of sexual selection in males or females being also under sexual selection on the same traits. It could also be that there is a genetic correlation and that plumage and coloration are under sexual selection in males but they are also expressed in females. Field studies with live animals are necessary to test these alternatives.

Keywords : Female choice; Hirundinidae; Plumage coloration; Sexual dimorphism; Sexual selection.

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