Reproduction (or procreation) is the biological process by which new individual organisms – "offspring" – are produced from their "parents". Reproduction is a fundamental feature of all known life; each individual organism exists as the result of reproduction. There are two forms of reproduction: asexual and sexual.
In asexual reproduction, an organism can reproduce without the involvement of another organism. Asexual reproduction is not limited to single-celled organisms. The cloning of an organism is a form of asexual reproduction. By asexual reproduction an organism creates a genetically similar or identical copy of itself. The evolution of sexual reproduction is a major puzzle for biologists. The two-fold cost of sex is that only 50% of organisms reproduce<ref>Ridley M (2004) Evolution, 3rd edition. Blackwell Publishing, p. 314.</ref> and organisms only pass on 50% of their genes.<ref name="maynard">John Maynard Smith The Evolution of Sex 1978.</ref>
Sexual reproduction typically requires the sexual interaction of two specialized organisms, called gametes, which contain half the number of chromosomes of normal cells and are created by meiosis, with typically a male fertilizing a female of the same species to create a fertilized zygote. This produces offspring organisms whose genetic characteristics are derived from those of the two parental organisms.
Intro Asexual reproduction Sexual reproduction Same-sex reproduction Reproductive strategies Asexual vs. sexual reproduction Life without reproduction Lottery principle See also Notes References Further reading External links
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