Sperm competition is "competition between sperm of two or more males for the fertilization of an ovum" (Parker 1970). Sperm competition is often compared to having tickets in a raffle; a male has a better chance of winning (i.e. fathering offspring) the more tickets he has (i.e. the more sperm he inseminates a female with). However, sperm are costly to produce (Olsson et al, 1997; Wedell et al, 2002) and the energy may be spent elsewhere such as defending a territory to the exclusion of other males; the distribution of resources are called strategies. The optimum amount is the evolutionarily stable strategy (ESS). Competition is the act of striving against another force for the purpose of achieving dominance or attaining a reward or goal, or out of a biological imperative such as survival. ... Different types of sperm cells: A) spermatozoon (motile), B) spermatium (non-motile), C) fertilization tube with sperm nuclei For other uses, see Sperm (disambiguation). ... The word male has the following meanings: In biology, it refers to one half of a heterogamous reproduction system, where the female is the other half. ... Categories: Biology stubs ... A human ovum Sperm cells attempting to fertilize an ovum An ovum (plural ova) is a haploid female reproductive cell or gamete. ... Cheap Tickets redirects here. ... A typical Neapolitan tombola. ... A strategy is a long term plan of action designed to achieve a particular goal. ... In game theory, an evolutionarily stable strategy (or ESS; also evolutionary stable strategy) is a strategy which if adopted by a population cannot be invaded by any competing alternative strategy. ...

Sperm competition may lead to evolutionary adaptations for producing more sperm, such as larger testes. Such adaptations cost and so species with low sperm competition invest in mate competition instead. Other means of sperm competition could include improving the sperm itself or its packaging materials (spermatophore). These sorts of competition can occur within a single male, if they involve genes that are expressed in the haploid sperm itself. This article is about evolution in biology. ... The eye is an adaptation. ... Human male anatomy The testicles, known medically as testes (singular testis), are the male generative glands in animals. ... A spermatophore is a capsule or mass created by males of various invertebrate species, containing spermatozoa and transferred in entirety to the female during sex. ... Haploid (meaning simple in Greek) cells have only one copy of each chromosome. ...

In primates Harcourt et al (1981) studied the relative size of testes compared to body mass against the mating system. They found that promiscuous chimpanzees have larger testes compared to polygynous gorillas. For the ecclesiastical use of this term, see primate (religion) Families 13, See classification A primate is any member of the biological order Primates, the group that contains all lemurs, monkeys, and apes, including humans. ... The testicle (from Latin testis, plural testes) is the male generative gland in animals. ... Body weight is simply the weight of anything, including humans. ... In sociobiology and behavioural ecology, the term mating system is used to describe the ways in which animal societies are structured in relation to sexual behavior. ... Promiscuity is the practice of making relatively casual and indiscriminate choices. ... Type species Simia troglodytes Blumenbach, 1775 distribution of Species Pan troglodytes Pan paniscus Chimpanzee, often shortened to chimp, is the common name for the two extant species in the genus Pan. ... The term polygyny (neo-Greek: poly+gune Many + Wives) is used in related ways in social anthropology and sociobiology. ... Type species Troglodytes gorilla Savage, 1847 distribution of Gorilla Species Gorilla gorilla Gorilla beringei The gorilla, the largest of the living primates, is a ground-dwelling omnivore that inhabits the forests of Africa. ...

The British biologist Geoffrey Parker proposed the concept of sperm competition in a 1970 paper. Professor Geoffrey Alan Parker FRS (born 24 May 1944) is a professor of biology at the University of Liverpool. ...

A million million spermatozoa,

All of them alive:

Out of their cataclysm but one poor Noah

Dare hope to survive.

And of that billion minus one

Might have chanced to be

Shakespeare, another Newton, a new Donne--

But the One was Me.

Shame to have ousted your betters thus.

Taking ark while the others remained outside!

Better for all of us, froward Homunculus,

If you'd quietly died! --Aldous Huxley

Aldous Leonard Huxley (July 26, 1894 – November 22, 1963) was an English writer and one of the most prominent members of the famous Huxley family. ...

See also

• Sperm heteromorphism
• Postcopulatory Reproductive Strategies
• Cryptic Female Choice

Sperm heteromorphism is the simultaneous production of two or more distinguishable types of sperm by a single male. ...

External links

• Sperm competition and the Kamikaze Sperm Hypothesis

References

• Baker, Robin 1996. Sperm Wars: The Science of Sex ISBN 0-7881-6004-4.
• Eberhard, William 1996 Female Control: Sexual Selection by Cryptic Female Choice ISBN 0691010846
• Harcourt, A.H., Harvey, P.H., Larson, S.G., and Short, R.V. 1981. Testis weight, body weight and breeding system in primates, Nature 293: 55-57.
• Olsson, M., Madsen, T. & Shine, R. 1997. Is sperm really so cheap? Costs of reproduction in male adders, Vipera berus. Proceedings of the Royal Society of London B 264: 455-459.
• Parker, Geoffrey A. 1970. Sperm competition and its evolutionary consequences in the insects, Biological Reviews 45: 525-567.
• Shackelford, T. K. & Pound, N. 2005. Sperm Competition in Humans : Classic and Contemporary Readings ISBN 0-387-28036-7.
• Simmons, Leigh W. 2001. Sperm competition and its evolutionary consequences in the insects. Princeton University Press, ISBN 0-691-05988-8 and ISBN 0-691-05987-X
• Snook, Rhonda R. Postcopulatory reproductive strategies. Encyclopedia of Life Sciences http://www.els.net
• Wedell, N., Gage, M.J.G, & Parker, G. A. 2002. Sperm competition, male prudence and sperm-limited females. Trends in Ecology & Evolution, 7: 313-320.