Reproduction
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- For other uses, see Reproduction (disambiguation).
Reproduction is perhaps most commonly used in the context of biological reproduction and sex:
- Sexual reproduction is a biological process by which organisms create descendants through the combination of genetic material. These organisms have two different adult sexes, male and female. New individuals are produced by the fusion of haploid gametes. Then it forms a diploid zygote.
- Asexual reproduction is a biological process by which an organism creates a genetically similar copy of itself without the combination of genetic material with another individual. For example, the Hydra (invertebrates of the order Hydroidea) and yeast are able to reproduce by budding. These organisms do not have different sexes, and they are capable of "splitting" themselves into two or more parts and regrow their body parts. Some 'asexual' species, like hydra and jellyfish, may also sexually reproduce. Most plants are capable of vegetative reproduction. Other ways of asexual reproduction are binary fission, fragmentation and spore formation.
There are a wide range of reproductive strategies employed by different species.
Some animals, like the human (sexually mature after adolescence) and Northern Gannet (5–6 years), produce few offspring. Others reproduce quickly, but unless raised in an artificial environment, most offspring do not survive to adults. A rabbit (mature after 8 months) produces 10–30 offspring per year, a Nile Crocodile (15 years) produces 50, and a fruit fly (10–14 days) produces up to 900. Both strategies can be favoured by evolution: animals with few offspring can spend time nurturing and protecting them, hence greatly decreasing the need to reproduce; on the other hand, animals with many offspring do not need to spend parental energy on nurturing, allowing more energy to be devoted to survival and more breeding.
These two strategies are known as K-selection (few offspring) and r-selection (many offspring). Which strategy is favoured depends on a wide range of circumstances.