White Rose University Consortium logo
University of Leeds logo University of Sheffield logo York University logo

Sperm competition and sperm midpiece size: no consistent pattern in passerine birds

Immler, S. and Birkhead, T.R. (2007) Sperm competition and sperm midpiece size: no consistent pattern in passerine birds. Proceedings of the Royal Society Series B: Biological Sciences, 274 (1609). pp. 561-568. ISSN 1471-2954


Download (290Kb)


Sperm competition is thought to be a major force driving the evolution of sperm shape and function. However, previous studies investigating the relationship between the risk of sperm competition and sperm morphometry revealed inconclusive results and marked differences between taxonomic groups. In a comparative study of two families of passerines (Fringillidae and Sylviidae) and also across species belonging to different passerine families, we investigated the relative importance of the phylogenetic background on the relationship between sperm morphometry and the risk of sperm competition. The risk of sperm competition was inferred from relative testis mass as an indicator of investment in sperm production. We found: (i) a significant positive association between both midpiece length and flagellum length and relative testis mass in the Fringillidae, (ii) a significant negative association between sperm trait dimensions and relative testis mass in the Sylviidae, and (iii) no association across all species. Despite the striking difference in the patterns shown by the Sylviidae and the Fringillidae, the relationship between midpiece length and flagellum length was positive in both families and across all species with positive allometry. Reasons for the differences and similarities between passerine families are discussed.

Item Type: Article
Copyright, Publisher and Additional Information: © 2007 the authors. This is an author prepared version of a paper published in Proceedings of the Royal Society Series B: Biological Sciences. Uploaded in accordance with the publisher's self-archiving policy.
Keywords: sperm competition, sperm size, midpiece size, Passeriformes
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: Repository Officer
Date Deposited: 22 Feb 2007
Last Modified: 10 Jun 2014 05:47
Published Version: http://www.journals.royalsoc.ac.uk/openurl.asp?gen...
Status: Published
Publisher: Royal Society
Refereed: Yes
Identification Number: 10.1098/rspb.2006.3752
URI: http://eprints.whiterose.ac.uk/id/eprint/2006

Actions (repository staff only: login required)