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By hook or by crook? Morphometry, competition and cooperation in rodent sperm

Immler, S., Moore, H.D.M., Breed, W.G. and Birkhead, T.R. (2007) By hook or by crook? Morphometry, competition and cooperation in rodent sperm. PLoS ONE, 2 (1). e170. ISSN 1932-6203


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Sperm design varies enormously across species and sperm competition is thought to be a major factor influencing this variation. However, the functional significance of many sperm traits is still poorly understood. The sperm of most murid rodents are characterised by an apical hook of the sperm head that varies markedly in extent across species. In the European woodmouse Apodemus sylvaticus (Muridae), the highly reflected apical hook of sperm is used to form sperm groups, or “trains,” which exhibited increased swimming velocity and thrusting force compared to individual sperm.

Methodology/Principal Findings

Here we use a comparative study of murine rodent sperm and demonstrate that the apical hook and sperm cooperation are likely to be general adaptations to sperm competition in rodents. We found that species with relatively larger testes, and therefore more intense sperm competition, have a longer, more reflected apical sperm hook. In addition, we show that sperm groups also occur in rodents other than the European woodmouse.


Our results suggest that in rodents sperm cooperation is more widespread than assumed so far and highlight the importance of diploid versus haploid selection in the evolution of sperm design and function.

Item Type: Article
Copyright, Publisher and Additional Information: © 2007 Immler et al. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited. Please see the PLoSOne site for further annotation and commentary http://dx.doi.org/10.1371/journal.pone.0000170
Institution: The University of Sheffield
Academic Units: The University of Sheffield > Faculty of Science (Sheffield) > School of Biological Sciences (Sheffield) > Department of Animal and Plant Sciences (Sheffield)
The University of Sheffield > Faculty of Medicine, Dentistry and Health (Sheffield) > School of Medicine (Sheffield) > Clinical Sciences Division South (Sheffield) > Reproductive and Developmental Medicine (Sheffield)
Depositing User: Repository Officer
Date Deposited: 23 Feb 2007
Last Modified: 05 Jun 2014 05:59
Published Version: http://dx.doi.org/10.1371/journal.pone.0000170
Status: Published
Publisher: PLoS
Refereed: Yes
Identification Number: 10.1371/journal.pone.0000170
URI: http://eprints.whiterose.ac.uk/id/eprint/2012

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