The status signalling hypothesis aims to explain within-species variation in ornamentation by suggesting that some ornaments signal dominance status. Here, we use multilevel meta-analytic models to challenge the textbook example of this hypothesis, the black bib of male house sparrows (Passer domesticus). We conducted a systematic review, and obtained primary data from published and unpublished studies to test whether dominance rank is positively associated with bib size across studies. Contrary to previous studies, the overall effect size (i.e. meta-analytic mean) was small and uncertain. Furthermore, we found several biases in the literature that further question the support available for the status signalling hypothesis. We discuss several explanations including pleiotropic, population- and context-dependent effects. Our findings call for reconsidering this established textbook example in evolutionary and behavioural ecology, and should stimulate renewed interest in understanding within-species variation in ornamental traits.

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Published in eLife, v. 7, e37385, p. 1-26.

© 2018, Sánchez-Tójar et al.

This article is distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use and redistribution provided that the original author and source are credited.

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Max-Planck-Gesellschaft open access funding to Alfredo Sánchez-Tójar. Max-Planck-Gesellschaft funding captive house sparrow population to Bart Kemenaers. National Science Foundation funding to David F. Westneat. Natural Environment Research Council grant NE/N013832/1 to Terry Burke. Volkswagen Foundation funding to Julia Schroeder. H2020 Marie Skłodowska-Curie Actions grant CIG PCIG12-GA-20120333096 to Julia Schroeder.

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Supplementary file 1. Decision spreadsheet of the systematic review. DOI: https://doi.org/10.7554/eLife.37385.011

Transparent reporting form. DOI: https://doi.org/10.7554/eLife.37385.012

Reporting standard 1. PRISMA statement. DOI: https://doi.org/10.7554/eLife.37385.013

All data generated or analysed during this study are openly available at the Open Science Frame- work. We direct the reader to this project in the main text and the reference list. Link: https://osf.io/cwkxb/ DOI: 10.17605/OSF.IO/CWKXB

elife-37385-supp1-v1.xlsx (67 kB)
Supplementary file 1. Decision spreadsheet of the systematic review.

elife-37385-transrepform-v1.pdf (587 kB)
Transparent reporting form.

elife-37385-fig3-v1.doc (101 kB)
Reporting standard 1. PRISMA statement.