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| '''Negative selection''' may refer to: | |||
| {{split}} | |||
| In ], '''negative selection''' has two different definitions depending on if it is due to ] or ]. | |||
| ==In biology== | |||
| In ] '''negative selection''' is the selective removal of rare ]s that are ]. This is also called ] and can result in the maintenance of conserved gene sequences between species over long periods of evolutionary time. The ongoing process of purging of deleterious alleles, due to the constant occurrence of new deleterious mutants, is referred to as ]. | |||
| *], the selective removal of rare alleles that are deleterious | |||
| *], when negative, rather than positive, traits of a species are selected for | |||
| ==In immunology== | |||
| In ] '''negative selection''' is where negative, rather than positive traits of a species are selected for. It is generally not desirable, but caused by bad ], wherein ]s eat the best plants or animals they have, leading to worse and worse stock; it occurred frequently, for example, in primitive ]. Another, more modern example, are regulations on fish and game, where fish below a certain sized had to be released, and deer below a certain size could not be hunted, leading to undersized deer and fish populations. Some proponents of ] argue that ] and other ], ], and ] practices cause negative selection in humans, also known as ]. According to them, man as a species manifests more and more negative traits as a result of this. In the case of ] and ], negative selection is used to ] for microorganisms that fail to possess a certain phenotype. An example of this is through ]. | |||
| *], in which B-cells and T-cells that recognize MHC molecules bound to peptides of self-origin, or just MHC molecules with high affinity are deleted from the repertoire of immune cells | |||
| ==In politics== | |||
| ---- | |||
| ⚫ | *], a process that occurs in rigid hierarchies, most notably dictatorships | ||
| ⚫ | |||
| The person on the top of the hierarchy, wishing to remain in power forever, chooses his associates with the prime criterion of incompetence - they must not be competent enough to remove him from power. The associates do the same with those below them in the hierarchy, and the hierarchy is progressively filled with more and more incompetent people. | |||
| {{disambiguation}} | |||
| If the dictator sees that he is threatened nonetheless, he will remove those that threaten him from their positions - "purge" the hierarchy. | |||
| Emptied positions in the hierarchy are normally filled with people from below - those who were less competent than their previous masters. | |||
| So, over the course of time, the hierarchy becomes less and less effective. As this happens relatively often, once the dictator dies, or is removed by some external influence, what remains is a grossly ineffective hierarchy. | |||
| ] | |||
Latest revision as of 06:08, 19 September 2024
Negative selection may refer to:
In biology
- Negative selection (natural selection), the selective removal of rare alleles that are deleterious
- Negative selection (artificial selection), when negative, rather than positive, traits of a species are selected for
In immunology
- Negative selection (immunology), in which B-cells and T-cells that recognize MHC molecules bound to peptides of self-origin, or just MHC molecules with high affinity are deleted from the repertoire of immune cells
In politics
- Negative selection (politics), a process that occurs in rigid hierarchies, most notably dictatorships
This disambiguation page lists articles associated with the title Negative selection.If an internal link led you here, you may wish to change the link to point directly to the intended article. Category: