Age-dependent female responses to a male ejaculate signal alter demographic opportunities for selection

Fricke, C., Green, Darrell, Mills, W. E. and Chapman, T. (2013) Age-dependent female responses to a male ejaculate signal alter demographic opportunities for selection. Proceedings of the Royal Society B: Biological Sciences, 280 (1766). p. 20130428. ISSN 0962-8452

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Abstract

A central tenet of evolutionary explanations for ageing is that the strength of selection wanes with age. However, data on age-specific expression and benefits of sexually selected traits are lacking—particularly for traits subject to sexual conflict. We addressed this by using as a model the responses of Drosophila melanogaster females of different ages to receipt of sex peptide (SP), a seminal fluid protein transferred with sperm during mating. SP can mediate sexual conflict, benefitting males while causing fitness costs in females. Virgin and mated females of all ages showed significantly reduced receptivity in response to SP. However, only young virgin females also showed increased egg laying; hence, there was a narrow demographic window of maximal responses to SP. Males gained significant ‘per mating’ fitness benefits only when mating with young females. The pattern completely reversed in matings with older females, where SP transfer was costly. The overall benefits of SP transfer (hence opportunity for selection) therefore reversed with female age. The data reveal a new example of demographic variation in the strength of selection, with convergence and conflicts of interest between males and ageing females occurring over different facets of responses to a sexually antagonistic trait.

Item Type: Article
Uncontrolled Keywords: sexual selection,sexual conflict,sex peptide,age-dependent selection,senescence,postmating responses
Faculty \ School: Faculty of Science > School of Biological Sciences
Faculty of Medicine and Health Sciences > Norwich Medical School
Depositing User: Pure Connector
Date Deposited: 25 Nov 2013 16:08
Last Modified: 24 Jul 2019 19:14
URI: https://ueaeprints.uea.ac.uk/id/eprint/44904
DOI: 10.1098/rspb.2013.0428

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