Negative selection (natural selection)
Encyclopedia
In natural selection
, negative selection or purifying 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, carriers of the harmful point mutation have fewer offspring each generation, reducing the frequency of the mutation in the gene pool.
In the case of strong negative selection on a locus, the purging of deleterious variants will 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. This effect increases with higher mutation rate but decreases with higher recombination rate.
Natural selection
Natural selection is the nonrandom process by which biologic traits become either more or less common in a population as a function of differential reproduction of their bearers. It is a key mechanism of evolution....
, negative selection or purifying selection is the selective removal of alleles that are deleterious. This can result in stabilizing selection
Stabilizing selection
-Description:Stabilizing or ambidirectional selection, , is a type of natural selection in which genetic diversity decreases as the population stabilizes on a particular trait value. This is probably the most common mechanism of action for natural selection...
through the purging of deleterious variations that arise.
Purging of deleterious alleles can be achieved on the population genetics
Population genetics
Population genetics is the study of allele frequency distribution and change under the influence of the four main evolutionary processes: natural selection, genetic drift, mutation and gene flow. It also takes into account the factors of recombination, population subdivision and population...
level, with as little as a single point mutation
Point mutation
A point mutation, or single base substitution, is a type of mutation that causes the replacement of a single base nucleotide with another nucleotide of the genetic material, DNA or RNA. Often the term point mutation also includes insertions or deletions of a single base pair...
being the unit of selection. In such a case, carriers of the harmful point mutation have fewer offspring each generation, reducing the frequency of the mutation in the gene pool.
In the case of strong negative selection on a locus, the purging of deleterious variants will result in the occasional removal of linked
Genetic linkage
Genetic linkage is the tendency of certain loci or alleles to be inherited together. Genetic loci that are physically close to one another on the same chromosome tend to stay together during meiosis, and are thus genetically linked.-Background:...
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. This effect increases with higher mutation rate but decreases with higher recombination rate.
See Also
- Balancing selectionBalancing selectionBalancing selection refers to a number of selective processes by which multiple alleles are actively maintained in the gene pool of a population at frequencies above that of gene mutation. This usually happens when the heterozygotes for the alleles under consideration have a higher adaptive value...
- Directional selectionDirectional selectionIn population genetics, directional selection is a mode of natural selection in which a single phenotype is favored, causing the allele frequency to continuously shift in one direction...
- Disruptive selectionDisruptive selectionDisruptive selection, also called diversifying selection, describes changes in population genetics in which extreme values for a trait are favored over intermediate values. In this case, the variance of the trait increases and the population is divided into two distinct groups...
- Stabilizing selectionStabilizing selection-Description:Stabilizing or ambidirectional selection, , is a type of natural selection in which genetic diversity decreases as the population stabilizes on a particular trait value. This is probably the most common mechanism of action for natural selection...
- Assortative matingAssortative matingAssortative mating , and the related concept Disassortative mating, is the phenomenon where a sexually reproducing organism chooses to mate with individuals that are similar or dissimilar to itself in some specific manner...