Negative selection (natural selection)

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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.

In the case of exceptionally strong negative selection on a locus combined with a high mutation rate, the frequent purging of deleterious variants may result in the occasional removal of linked variation, producing a decrease in the level of variation surrounding the locus under selection. The accidental purging of non-deleterious alleles due to such spatial proximity to deleterious alleles is called background selection. Background selection is believed to be a relatively rare phenomenon in most genomes.

[edit] References

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

v • d • e Topics in molecular evolution Natural selection Background selection • Balancing selection • Directional selection • Disruptive selection • Negative selection • Stabilizing selection • Selective sweep Models Models of DNA evolution • Models of nucleotide substitution • Allele frequency • Ka/Ks ratio • Tajima's D Molecular processes Gene conversion • Gene duplication • Silent mutation • Synonymous substitution