Abstract
BackgroundCarotenoid plumage is of widespread use in bird communication. Carotenoid-based feather colouration has recently been shown to be dependent on both pigment concentration and feather structure. If these two components are determined differently, one plumage patch may potentially convey different aspects of individual quality.Methodology/Principal FindingsWe evaluated the effects of genetic and environmental factors on carotenoid-based yellow breast colouration of Great Tit (Parus major) nestlings. By partial cross-fostering, we separated the genetic and pre-natal vs. post-natal parental effects on both the structural and the pigment-based component of carotenoid-based plumage colouration. We also simultaneously manipulated the post-hatching environment by brood size manipulation. The structural component of nestling colouration reflected features of female colouration. On the other hand, the pigment-based component was more affected by rearing conditions presumably representing food quality. While the structural component was related to both origin- and environment-related factors, the pigment-based component seemed to be environment-dependent only. These results support the notion that pigment-based and structural components of feather colouration are determined differently.Conclusions/SignificanceChromatic and achromatic components of carotenoid-based feather colouration reflected different aspects of individual quality and history, and thus may potentially form a multicomponent signal.
Highlights
Signal design is a very important component of animal communication
Great Tit nestlings reared by older mothers and those that hatched later in the season were more intensely yellow
Carotenoid chroma of nestlings was independent of the colouration of both the rearing and the genetic mother and of the antioxidant concentration in the egg yolk
Summary
Signal design is a very important component of animal communication. In visual signals, colouration and overall patterning may be critical for signal efficiency [1]. Plumage colouration is a conspicuous and versatile trait with important signalling functions [2]. Both feather structure and pigments can determine plumage colouration and are important drivers of signal design and efficiency [3]. Interactions between light-scattering tissue structures and pigment molecules are common in animal colouration, but only one component is typically considered at a time [5]. Carotenoid-based feather colouration has recently been shown to be dependent on both pigment concentration and feather structure. If these two components are determined differently, one plumage patch may potentially convey different aspects of individual quality
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