Negative selection (artificial selection)

For other uses, see Negative selection (disambiguation).

In artificial selection, negative selection is where negative, rather than positive, traits of a species are selected for evolutionary continuance. It is generally not desirable, but may be caused by man-made conditions such as bad management, or like when humans eat the best plants or animals they have, leading to worse and worse stock; for example, it occurred frequently in primitive beekeeping.^{[citation needed]} Another more recent example are regulations on fish and deer, where fish below a certain desired size will be set free, and deer suffering small antlers would less likely to be hunted, leading to undersized fish and small-antlered deer populations; the same case applies to the elephant's tusks.^[1][2]

Some proponents of Social Darwinism and eugenics argue that medicine and other technological, societal, and cultural practices cause negative selection in humans, better known as dysgenics. According to them, human manifests more and more negative traits. ^[3]

In the case of microbiology and molecular biology, negative selection is used to screen for microorganisms that fail to possess a certain phenotype. An example of this is through replica plating.

Examples

The shellfishes Concholepas concholepas (Chilean abalone) and Loxechinus albus (Chilean sea urchin) have been exposed to over-extraction during a long time. Populations have shrunk and a recent study shows that extraction is making an artificial selection to eliminate faster-growing individuals.^[4] The same study also showed that populations in Chile are relatively homogeneous with low genetic variability.

See also

• Devolution
• Genetic deterioration

References

1. ^ McCarthy, Michael (19 June 2001). "Poachers have created breed of tuskless elephant". The Independent. http://www.independent.co.uk/news/world/asia/poachers-have-created-breed-of-tuskless-elephant-674663.html. Retrieved 2010-07-11. 
2. ^ Gray, Richard (20 Jan 2008). "Why elephants are not so long in the tusk". Telegraph. http://www.telegraph.co.uk/science/science-news/3322455/Why-elephants-are-not-so-long-in-the-tusk.html. Retrieved 2010-07-11. 
3. ^ Lynn, Richard (1996). Dysgenics: Genetic Deterioration in Modern Populations. Praeger Publishers. ISBN 0275949176. 
4. ^ (Spanish)[1] Fondef