Sperm competition in tropical versus temperate zone birds
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Date
2012-11-21
Journal Title
Journal ISSN
Volume Title
Publisher
Royal Society Publishing
Abstract
Sperm competition represents an important component of post-copulatory
sexual selection. It has been argued that the level of sperm competition
declines in birds towards the equator. However, to date, sperm competition
estimates have been available mainly for avian species inhabiting the
northern temperate zone. Here we apply a novel approach, using the coefficient
of between-male variation (CVbm) in sperm size as an index for sperm
competition risk, in a comparative analysis of 31 Afrotropical and 99 northern
temperate zone passerine species. We found no difference in sperm competition
risk between the two groups, nor any relationship with migration
distance. However, a multivariate model indicated that sperm competition
risk was highest in species with a combination of low body mass and few
eggs per clutch. The effect of clutch size was most pronounced in tropical
species, which indicates that sperm competition risk in tropical and temperate
species is differently associated with particular life-history traits. Although
tropical species had lower sperm competition risk than temperate zone species
for overlapping clutch sizes, the idea of a generally reduced risk of sperm
competition in tropical birds was not supported by our analysis.
Description
Staff Publication
Keywords
clutch size,, extra-pair paternity, life history,, post-copulatory sexual selection,, sperm phenotype
Citation
Albrecht T, Kleven O, Kreisinger J, Laskemoen T, Omotoriogun TC, Ottosson U, Reif J, Sedla´cˇek O, Horˇa´k D, Robertson RJ, Lifjeld JT. 2013 Sperm competition in tropical versus temperate zone birds. Proc R Soc B 280: 20122434. http://dx.doi.org/10.1098/rspb.2012.2434