Sperm competition and maternal effects differentially influence testis and sperm size in Callosobruchus maculatus

Gay , L. and Hosken, D. J. and Vasudev, R. and Tregenza, T. and Eady, P. E. (2009) Sperm competition and maternal effects differentially influence testis and sperm size in Callosobruchus maculatus. Journal of Evolutionary Biology, 22 (5). pp. 1143-1150. ISSN 1010-061X

Full content URL: http://onlinelibrary.wiley.com/doi/10.1111/j.1420-...

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Sperm competition and maternal effects differentially influence testis and sperm size in Callosobruchus maculatus

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Abstract

The evolutionary factors affecting testis size are well documented, with sperm
competition being of major importance. However, the factors affecting sperm
length are not well understood; there are no clear theoretical predictions and
the empirical evidence is inconsistent. Recently, maternal effects have been
implicated in sperm length variation, a finding that may offer insights into its
evolution. We investigated potential proximate and microevolutionary factors
influencing testis and sperm size in the bruchid beetle Callosobruchus maculatus
using a combined approach of an artificial evolution experiment over 90
generations and an environmental effects study. We found that while
polyandry seems to select for larger testes, it had no detectable effect on
sperm length. Furthermore, population density, a proximate indicator of
sperm competition risk, was not significantly associated with sperm length or
testis size variation. However, there were strong maternal effects influencing sperm length.

Keywords:Callosobruchus maculatus;, Coleoptera, maternal effect;, polyandry, sperm competition;, sperm length;, testis size.
Subjects:C Biological Sciences > C142 Reproductive Biology
C Biological Sciences > C182 Evolution
C Biological Sciences > C100 Biology
Divisions:College of Science > School of Life Sciences
ID Code:4317
Deposited On:26 Mar 2011 23:15

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