Eggshell coloration and its importance in postmating sexual selection |
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| Authors: | Miroslav Polá?ek Matteo Griggio Ivan Mik?ík Michaela Bartíková Manfred Eckenfellner Herbert Hoi |
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| Affiliation: | 1. Institute of Zoology, Slovak Academy of Sciences, Bratislava, Slovakia;2. Department of Integrative Biology and Evolution, Konrad Lorenz Institute of Ethology, University of Veterinary Medicine, Vienna, Vienna, Austria;3. Department of Biology, University of Padova, Padova, Italy;4. Department of Analytical Chemistry, Faculty of Chemical Technology, University of Pardubice, Pardubice, Czech Republic;5. Neufang 6, Feuersbrunn, Austria |
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| Abstract: | Avian eggshell color seems to fulfill multiple functions, some of them being structural and others signaling. In this study, we tested whether or not eggshell coloration may play a role in sexual selection of Tree Sparrows (Passer montanus). According to the “Sexually selected eggshell coloration” hypothesis, eggshell coloration signals female, egg or chick quality and males adjust parental investment according to this signal. Eggs of this species are covered with brown spots and patches, and variation between clutches is high. We found that eggshell coloration correlates with both protoporphyrin and biliverdin, but protoporphyrin concentrations are ten times higher. Eggshell coloration reflects egg and offspring quality, but not female quality. Thus, eggshell coloration may signal female postmating investment in offspring rather than female quality. Furthermore, differential allocation in terms of maternal investment is supported by the fact that females lay more pigmented clutches when mated to males with bigger melanin‐based ornaments relative to their own. Moreover, males invested proportionally more to chicks that hatched from more pigmented clutches. Our correlative results thus seem to support a role of sexual selection in the evolution of eggshell coloration in birds laying brown eggs, pigmented mainly by protoporphyrin. |
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| Keywords: | differential allocation eggshell coloration female quality paternal investment sexual selection Tree Sparrow |
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