Reproduction
Reproduction is the creation of one thing as a copy of, product of, or replacement for a similar thing, e.g. photocopying.
It 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.
- 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 in half or more and regrow their body parts. Some asexual species, like hydra and jellyfish, will also be able to perform sexual reproductions. Most plants are capable of vegetative reproduction.
Some animals, like 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 offsprings per year, a Nile Crocodile (15 years) produce 50, and fruit fly (10-14 days) produce up to 900. Both strategies can be favoured by evolution: animals with few offspring can 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.
See also: conjugation, sexual intercourse, father, mother, self-replication, reproductive technology
