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Genetic drift, also known as random genetic drift, allelic drift or the Wright effect, [1] is the change in the frequency of an existing gene variant in a population due to random chance. [ 2 ] Genetic drift may cause gene variants to disappear completely and thereby reduce genetic variation . [ 3 ]
The drift-barrier hypothesis is an evolutionary hypothesis formulated by Michael Lynch in 2010. [1] It suggests that the perfection of the performance of a trait, in a specific environment, by natural selection will hit a hypothetical barrier.
These can be caused by genetic drift or by mutation, and they will tend to slow down the process of evolution by natural selection. [ 2 ] This is most easily seen by considering the case of disequilibria caused by mutation: Consider a population of individuals whose genome has only two genes, a and b .
Average time to fixation N e is the effective population size, the number of individuals in an idealised population under genetic drift required to produce an equivalent amount of genetic diversity. Usually the population statistic used to define effective population size is heterozygosity, but others can be used.
In the absence of selection, mutation, genetic drift, or other forces, allele frequencies p and q are constant between generations, so equilibrium is reached. The principle is named after G. H. Hardy and Wilhelm Weinberg, who first demonstrated it mathematically.
[further explanation needed] Speciation by genetic drift is a specific case of peripatric speciation which in itself occurs in rare instances. [18] It takes place when a random change in genetic frequency of population favours the survival of a few organisms of the species with rare genes which cause reproductive mutation.
Genetic drift is the process by which allele frequencies fluctuate within populations. Natural selection and genetic drift propel evolution forward, and through evolution, alleles can become fixed. [8] [9] Processes of natural selection such as sexual, convergent, divergent, or stabilizing selection pave the way for allele fixation. One way ...
This stochastic process is assumed to obey equations describing random genetic drift by means of accidents of sampling, rather than for example genetic hitchhiking of a neutral allele due to genetic linkage with non-neutral alleles. After appearing by mutation, a neutral allele may become more common within the population via genetic drift.