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Sperm design and variation in the New World blackbirds (Icteridae)

Lüpold, S., Linz, G.M. and Birkhead, T.R. (2009) Sperm design and variation in the New World blackbirds (Icteridae). Behavioral Ecology and Sociobiology, 63 (6). pp. 899-909. ISSN 0340-5443


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Post-copulatory sexual selection (PCSS) is thought to be one of the evolutionary forces responsible for the rapid and divergent evolution of sperm design. However, whereas in some taxa particular sperm traits are positively associated with PCSS, in other taxa, these relationships are negative, and the causes of these different patterns across taxa are poorly understood. In a comparative study using New World blackbirds (Icteridae), we tested whether sperm design was influenced by the level of PCSS and found significant positive associations with the level of PCSS for all sperm components but head length. Additionally, whereas the absolute length of sperm components increased, their variation declined with the intensity of PCSS, indicating stabilizing selection around an optimal sperm design. Given the diversity of, and strong selection on, sperm design, it seems likely that sperm phenotype may influence sperm velocity within species. However, in contrast to other recent studies of passerine birds, but consistent with several other studies, we found no significant link between sperm design and velocity, using four different species that vary both in sperm design and PCSS. Potential reasons for this discrepancy between studies are discussed.

Item Type: Article
Copyright, Publisher and Additional Information: © 2009 Springer Verlag. This is an author produced version of a paper published in Behavioral Ecology and Sociobiology. Uploaded in accordance with the publisher's self archiving policy.
Keywords: sperm competition, sperm morphology, sperm velocity, phylogenetic analysis, passerine birds
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)
Depositing User: Dr Stefan Luepold
Date Deposited: 30 Apr 2009 15:04
Last Modified: 15 Sep 2014 01:38
Published Version: http://dx.doi.org/10.1007/s00265-009-0733-6
Status: Published
Publisher: Springer Verlag
Refereed: Yes
Identification Number: 10.1007/s00265-009-0733-6
URI: http://eprints.whiterose.ac.uk/id/eprint/8556

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