Sperm competition and sperm midpiece size: no consistent pattern in passerine birds
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Sperm competition and sperm midpiece size: no consistent pattern in passerine birds.
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 spe...
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Ornithologists have known for a long time that males of monogamous bird species sometimes copulate with females from other pairs, but it is only in the last few years that researchers have shown that these extra-pair copulations can result in offspring and increase male reproductive success. Males time their extra-pair copulations to coincide with the period when females are fertilizable, and t...
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Comparative analyses suggest that a variety of ecological and behavioural factors contribute to the tremendous variability in extrapair mating among birds. In an analysis of 1010 species of birds, we examined several ecological and behavioural factors in relation to testes size; an index of sperm competition and the extent of extrapair mating. In univariate and multivariate analyses, testes siz...
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ژورنال
عنوان ژورنال: Proceedings of the Royal Society B: Biological Sciences
سال: 2006
ISSN: 0962-8452,1471-2954
DOI: 10.1098/rspb.2006.3752