Simons, M.J.P. orcid.org/0000-0001-7406-7708, Briga, M. and Verhulst, S. (2016) Stabilising survival selection on pre-senescent expression of a sexual ornament followed by a terminal decline. Journal of Evolutionary Biology, 29 (7). pp. 1368-1378. ISSN 1010-061X
Abstract
Senescence is a decrease in functional capacity, increasing mortality rate with age. Sexual signals indicate functional capacity, because costs of ornamentation ensure signal honesty, and are therefore expected to senesce, tracking physiological deterioration and mortality. For sexual traits, mixed associations with age and positive associations with life expectancy have been reported. However, whether these associations are caused by selective disappearance and/or within-individual senescence of sexual signals, respectively, is not known. We previously reported that zebra finches with redder bills had greater life expectancy, based on a single bill colour measurement per individual. We here extend this analysis using longitudinal data and show that this finding is attributable to terminal declines in bill redness in the year before death, with no detectable change in presenescent redness. Additionally, there was a quadratic relationship between presenescent bill colouration and survival: individuals with intermediate bill redness have maximum survival prospects. This may reflect that redder individuals overinvest in colouration and/or associated physiological changes, while below-average bill redness probably reflects poorer phenotypic quality. Together, this pattern suggests that bill colouration is defended against physiological deterioration, because of mate attraction benefits, or that physiological deterioration is not a gradual process, but accelerates sharply prior to death. We discuss these possibilities in the context of the reliability theory of ageing and sexual selection.
Metadata
Item Type: | Article |
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Authors/Creators: |
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Copyright, Publisher and Additional Information: | © 2016 The Authors. Journal of Evolutionary Biology published by John Wiley & Sons Ltd on behalf of European Society for Evolutionary Biology. This is an open access article under the terms of the Creative Commons Attribution License (https://creativecommons.org/licenses/by/4.0/), which permits use, distribution and reproduction in any medium, provided the original work is properly cited. |
Keywords: | ageing; bird; carotenoids; colouration; demography; reliability theory of ageing; selective disappearance; sexual selection; zebra finch |
Dates: |
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Institution: | The University of Sheffield |
Academic Units: | The University of Sheffield > Faculty of Science (Sheffield) > School of Biosciences (Sheffield) > Department of Animal and Plant Sciences (Sheffield) |
Funding Information: | Funder Grant number WELLCOME TRUST (THE) 107400/Z/15/Z NATURAL ENVIRONMENT RESEARCH COUNCIL NE/N013832/1 |
Depositing User: | Symplectic Sheffield |
Date Deposited: | 27 Jun 2016 08:06 |
Last Modified: | 26 Jun 2017 11:30 |
Published Version: | http://dx.doi.org/10.1111/jeb.12877 |
Status: | Published |
Publisher: | Wiley |
Refereed: | Yes |
Identification Number: | 10.1111/jeb.12877 |
Open Archives Initiative ID (OAI ID): | oai:eprints.whiterose.ac.uk:101204 |
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