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Maintenance of sperm variation in a highly promiscuous wild bird

Citation

Calhim, S and Double, MC and Margraf, N and Birkhead, TR and Cockburn, A, Maintenance of sperm variation in a highly promiscuous wild bird, PLoS ONE, 6, (12) Article e28809. ISSN 1932-6203 (2011) [Refereed Article]


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Copyright Statement

Copyright 2011 Calhim et al. Licensed under Creative Commons Attribution 4.0 International (CC BY 4.0) https://creativecommons.org/licenses/by/4.0/

DOI: doi:10.1371/journal.pone.0028809

Abstract

Postcopulatory sexual selection is an important force in the evolution of reproductive traits, including sperm morphology. In birds, sperm morphology is known to be highly heritable and largely condition-independent. Theory predicts, and recent comparative work corroborates, that strong selection in such traits reduces intraspecific phenotypic variation. Here we show that some variation can be maintained despite extreme promiscuity, as a result of opposing, copulation-role-specific selection forces. After controlling for known correlates of siring success in the superb fairy-wren (Malurus cyaneus), we found that (a) lifetime extra-pair paternity success was associated with sperm with a shorter flagellum and relatively large head, and (b) males whose sperm had a longer flagellum and a relatively smaller head achieved higher within-pair paternity. In this species extrapair copulations occur in the same morning, but preceding, pair copulations during a female's fertile period, suggesting that shorter and relatively larger-headed sperm are most successful in securing storage (defense), whereas the opposite phenotype might be better at outcompeting stored sperm (offense). Furthermore, since cuckolding ability is a major contributor to differential male reproductive output, stronger selection on defense sperm competition traits might explain the short sperm of malurids relative to other promiscuous passerines.

Item Details

Item Type:Refereed Article
Keywords:animal cell, article, bird, cell structure, copulation, female, fertility, male
Research Division:Biological Sciences
Research Group:Ecology
Research Field:Population Ecology
Objective Division:Expanding Knowledge
Objective Group:Expanding Knowledge
Objective Field:Expanding Knowledge in the Biological Sciences
Author:Double, MC (Dr Michael Double)
ID Code:119640
Year Published:2011
Web of Science® Times Cited:20
Deposited By:Centre for Ecology and Biodiversity
Deposited On:2017-08-03
Last Modified:2017-10-16
Downloads:3 View Download Statistics

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