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2006 The Society for the Study of Evolution. All rights reserved. Evolution, 60(11), 2006, pp. 23702380
 

Summary: 2370
2006 The Society for the Study of Evolution. All rights reserved.
Evolution, 60(11), 2006, pp. 2370­2380
MELANIN-BASED COLORATION IS A NONDIRECTIONALLY SELECTED
SEX-SPECIFIC SIGNAL OF OFFSPRING DEVELOPMENT IN THE ALPINE SWIFT
PIERRE BIZE,1 JULIEN GASPARINI,2 AURE´ LIE KLOPFENSTEIN,2 RES ALTWEGG,3 AND ALEXANDRE ROULIN2,4
1Division of Environmental and Evolutionary Biology, Institute of Biomedical and Life Sciences, Graham Kerr Building,
Glasgow University, Glasgow G12 8QQ, United Kingdom
2Department of Ecology and Evolution, University of Lausanne, Biophore, 1015 Lausanne, Switzerland
3Avian Demography Unit, Department of Statistical Sciences, University of Cape Town, 7701 Rondebosch, South Africa
4E-mail: alexandre.roulin@unil.ch
Abstract. Two mutually exclusive hypotheses have been put forward to explain the evolution and adaptive function
of melanin-based color traits. According to sexual selection theory melanism is a directionally selected signal of
individual quality, whereas theory on the maintenance of genetic polymorphism proposes that alternative melanin-
based variants achieve equal fitness. Alpine swift (Apus melba) males and females have a conspicuous patch of white
feathers on the breast with their rachis varying continuously from white to black, and hence the breast varies from
white to striated. If this trait is a sexually selected signal of quality, its expression should be condition dependent and
the degree of melanism directionally selected. If variation in melanism is a polymorphism, its expression should be
genetically determined and fitness of melanin-based variants equal. We experimentally tested these predictions by
exchanging eggs or hatchlings between randomly chosen nests and by estimating survival and reproduction in relation

  

Source: Altwegg, Res - Avian Demography Unit, Department of Statistical Sciences, University of Cape Town

 

Collections: Environmental Sciences and Ecology