Is eggshell colouration related to the sex of the embryo in the northern lapwing Vanellus vanellus?
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This study focuses on eggshell pigmentation in the northern lapwing Vanellus vanellus, a shorebird in the plover family. The pigmentation of dark spots is attributed to the organic compound protoporphyrin, which is associated with oxidative stress in females. Thus, deposition of protoporphyrin is thought to come with a cost, and under the handicap theory, reliably showcase good health. Following the signalling-function hypothesis, spots are thought to be visual cues, enabling males to assess the quality of the eggs and/or their partner and thus permitting them to modulate parental investment accordingly. From findings of females modulating offspring sex ratio according to expected fitness of each sex, eggs heavily covered in spots were predicted to be male-biased. The computer program SpotEgg was used to analyse images of the eggs, providing values for total coverage of spots, distribution of spots, average spot size and number of spots. However, neither of the variables showed a significant relationship with sex of the embryo. This conflicts with the only study to date analysing egg spotting in relation to sex of the embryos (Corti et al., 2018). Further investigation as to whether eggshell colouration is linked to embryonic sex is required.
PublisherThe University of Bergen
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