Sperm competition in birds
نویسندگان
چکیده
منابع مشابه
Sperm competition in birds.
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...
متن کاملSperm competition selects beyond relative testes size in birds.
Sperm morphology varies considerably across taxa, and postcopulatory sexual selection is thought to be one of the main forces responsible for this diversity. Several studies have investigated the effects of the variation in sperm design on sperm function, but the consequences of variation in sperm design on testis morphology have been overlooked. Testes size or architecture may determine the si...
متن کاملSperm competition and sexually size dimorphic brains in birds.
Natural selection may favour sexually similar brain size owing to similar selection pressures in males and females, while sexual selection may lead to sexually dimorphic brains. For example, sperm competition involves clear-cut sex differences in behaviour, as males display, mate guard and copulate with females, while females choose among males, and solicit or reject copulations. These behaviou...
متن کاملSperm competition and the evolution of testes size in birds.
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...
متن کاملSperm competition in tropical versus temperate zone birds.
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 (CV...
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ژورنال
عنوان ژورنال: Reviews of Reproduction
سال: 1998
ISSN: 1359-6004
DOI: 10.1530/ror.0.0030123