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Nestling birds solicit food from their parents by displaying their open brightly coloured gapes. Carotenoids affect gape colour, but also play a central role in immunostimulation. Therefore, we hypothesize that, by differentially allocating resources to nestlings with more brightly coloured gapes, parents favour healthy offspring which are able to allocate(More)
Maternal effects such as androgen in avian eggs can mediate evolutionary responses to selection, allowing manipulation of offspring phenotype and promoting trans-generational adaptive effects. We tested the predictions of two adaptive hypotheses that have been proposed to explain female variation in yolk androgen allocation in birds, using the barn swallow(More)
abstract: Carotenoids exert immunomodulating, immunostimu-lating, and antioxidant actions in mammals and are major determinants of coloration in animals. Honest advertisement models of sexual selection propose that male ornaments, including coloration, are reliable indicators of male quality. Because of their simultaneous effects on male coloration and(More)
Early arrival at the breeding area after spring migration determines several fitness benefits to migratory birds, including an early start of reproduction and a greater seasonal reproductive success. Environmental conditions determine the onset of migration at the population level, while physiological costs associated with migration and imposed on(More)
In some passerines, parents allocate more food to offspring with the brightest red gapes, but the function of parental decisions based on offspring gape coloration is unknown. We hypothesize that gape coloration is part of a communication system where nestlings reveal their condition to attending parents, which may thus base their decisions on reliable(More)
abstract: Parents are selected to maximize their fitness by allocating care among their progeny in relation to the differential reproductive value of offspring. Nestlings have been hypothesized to signal need for parental care reliably through their begging behavior, but offspring condition as reflected by their reproductive value may likewise affect(More)
Measurements of optical properties carried out at visible and NIR wavelengths on many samples of Intralipid 20% showed a high stability and surprisingly small batch-to-batch variations. Measurements have been carried out in a short time interval using samples from nine different batches with expiry dates spreading over ten years. For the specific reduced(More)
Variation in the expression of sexually selected traits among individuals is widely investigated on the premise that these traits evolved to signal male quality. Significant repeatabilities of sexual signals and their associations with condition, mating success, survivorship and age may be the signatures of sexual selection. However, little is known about(More)
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