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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 ]
For example, an ancestral species has the alleles a and b fixed in its population, resulting in all individuals having the aabb genotype. When two descendant populations are separated from each other and each undergo several mutations the allele A can occur in one population while the allele B occurs in the second population.
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 ...
Allelic heterogeneity is the phenomenon in which different mutations at the same locus lead to the same or very similar phenotypes.These allelic variations can arise as a result of natural selection processes, as a result of exogenous mutagens, genetic drift, or genetic migration.
Both genetic drift and genetic draft are random evolutionary processes, i.e. they act stochastically and in a way that is not correlated with selection at the gene in question. Drift is the change in the frequency of an allele in a population due to random sampling in each generation. [9]
Some models for migration inherently include nonrandom mating (Wahlund effect, for example). For those models, the Hardy–Weinberg proportions will normally not be valid. Small population size can cause a random change in allele frequencies. This is due to a sampling effect, and is called genetic drift. Sampling effects are most important when ...
The effective population size (N e) is the size of an idealised population that would experience the same rate of genetic drift as the real population. [1] Idealised populations are those following simple one-locus models that comply with assumptions of the neutral theory of molecular evolution.
Population structure (also called genetic structure and population stratification) is the presence of a systematic difference in allele frequencies between subpopulations. In a randomly mating (or panmictic ) population, allele frequencies are expected to be roughly similar between groups.