منابع مشابه
Sperm competition
The existence and evolutionary significance of sexual selection through sperm competition was first realized by Geoff Parker in a prescient and influential review published in 1970. Parker recognized that competition between males for fertilizations will continue after mating, if the sperm of two or more males overlap near the site of fertilization in females. The process of sperm competition w...
متن کاملSperm competition in mammals.
Although Darwin identified the evolutionary significance of competition between males in the context of reproduction, it is only in the past few decades that we have begun to appreciate the importance of competition at the gametic level. Sperm competition, defined as competition between the sperm of two or more males for fertilization of the same set of ova, is now recognised as a key selective...
متن کاملSperm 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 influences sperm size in mammals.
Among mammals sperm competition leads to selection for increased sperm numbers but it is not known whether it also leads to changes in sperm size. Two contrasting theoretical predictions have been made. The first hypothesis relies on the assumption that there is a trade-off between sperm numbers and sperm size and predicts that, in species confronting sperm competition, there will be a concomit...
متن کاملSperm Viability and Sperm Competition in Insects
Sperm quality plays an important role in vertebrates in determining which male has the advantage when two or more males compete to fertilize a female's ova. In insects, however, the importance of sperm quality has never been considered, despite sperm competition being widespread and well studied in this group. We tested the hypothesis that sperm viability, measured as the proportion of live spe...
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ژورنال
عنوان ژورنال: Nature
سال: 1999
ISSN: 0028-0836,1476-4687
DOI: 10.1038/22650