Negative_selection_(natural_selection)

For other uses, see Negative selection (disambiguation).

Negative selection, in natural selection, is the selective removal of alleles that are deleterious. This can result in stabilizing selection through the purging of deleterious variations that arise.

Purging of deleterious alleles can be achieved on the population genetics level, with as little as a single point mutation being the unit of selection. In such a case, individuals bearing the allele selected against might simply have less offspring on average generation after generation.

On the other hand, the deleterious effect of an allele can also increase the benefit of larger-scale mutations, such as deletions that take away whole chunks of DNA at once and which often are to some extent deleterious themselves.

In the latter case, neighboring polymorphic sites are affected too. If an allele that on its own would be slightly beneficial occurs in the gene next to one of which a more deleterious allele exists, under certain circumstances not having either may (for a polyploid organism for example) be the least detrimental possibility. The accidental purging of non-deleterious alleles due to such spatial proximity to deleterious ones is called background selection.

References

• Charlesworth, B., Morgan, M. T. and Charlesworth, D. 1993. The effect of deleterious mutations on neutral molecular variation. Genetics 134, 1289-1303. Link

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