In natural selection, negative selection[1] or purifying selection is the selective removal of alleles that are deleterious. This can result in stabilising selection through the purging of deleterious genetic polymorphisms that arise through random mutations.[2][3]
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 incidental purging of non-deleterious alleles due to such spatial proximity to deleterious alleles is called background selection.[4] This effect increases with lower mutation rate but decreases with higher recombination rate.[5]
Purifying selection can be split into purging by non-random mating (assortative mating) and purging by genetic drift. Purging by genetic drift can remove primarily deeply recessive alleles, whereas natural selection can remove any type of deleterious alleles.[6]
See also[edit]
- Assortative mating
- Balancing selection
- Directional selection
- Disruptive selection
- Dysgenics
- Fluctuating selection
- Genetic purging
- Koinophilia
- Mutation–selection balance
- Stabilizing selection
References[edit]
- ^ Loewe L (2008). "Negative selection". Nature Education. 1 (1): 59.
- ^ Tien NS, Sabelis MW, Egas M (March 2015). "Inbreeding depression and purging in a haplodiploid: gender-related effects". Heredity. 114 (3): 327–32. doi:10.1038/hdy.2014.106. PMC 4815584. PMID 25407077.
- ^ Gulisija D, Crow JF (May 2007). "Inferring purging from pedigree data". Evolution; International Journal of Organic Evolution. 61 (5): 1043–51. doi:10.1111/j.1558-5646.2007.00088.x. PMID 17492959. S2CID 24302475.
- ^ Charlesworth B, Morgan MT, Charlesworth D (August 1993). "The effect of deleterious mutations on neutral molecular variation". Genetics. 134 (4): 1289–303. doi:10.1093/genetics/134.4.1289. PMC 1205596. PMID 8375663.
- ^ Hudson RR, Kaplan NL (December 1995). "Deleterious background selection with recombination". Genetics. 141 (4): 1605–17. doi:10.1093/genetics/141.4.1605. PMC 1206891. PMID 8601498.
- ^ Glémin S (December 2003). "How are deleterious mutations purged? Drift versus nonrandom mating". Evolution; International Journal of Organic Evolution. 57 (12): 2678–87. doi:10.1111/j.0014-3820.2003.tb01512.x. PMID 14761049.
Well, that’s interesting to know that Psilotum nudum are known as whisk ferns. Psilotum nudum is the commoner species of the two. While the P. flaccidum is a rare species and is found in the tropical islands. Both the species are usually epiphytic in habit and grow upon tree ferns. These species may also be terrestrial and grow in humus or in the crevices of the rocks.
View the detailed Guide of Psilotum nudum: Detailed Study Of Psilotum Nudum (Whisk Fern), Classification, Anatomy, Reproduction