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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 genetic drift caused by a population bottleneck can change the proportional random distribution of alleles and even lead to loss of alleles. The chances of inbreeding and genetic homogeneity can increase, possibly leading to inbreeding depression. Smaller population size can also cause deleterious mutations to accumulate. [3]
Population size is directly associated with amount of genetic drift, and is the underlying cause of effects like population bottlenecks and the founder effect. [1] Genetic drift is the major source of decrease of genetic diversity within populations which drives fixation and can potentially lead to speciation events. [1]
The founder effect occurs when a small group of migrants—not genetically representative of the population from which they came—establish in a new area. [4] [5] In addition to founder effects, the new population is often very small, so it shows increased sensitivity to genetic drift, an increase in inbreeding, and relatively low genetic ...
Population structure commonly arises from physical separation by distance or barriers, like mountains and rivers, followed by genetic drift. Other causes include gene flow from migrations, population bottlenecks and expansions, founder effects, evolutionary pressure, random chance, and (in humans) cultural factors. Even in lieu of these factors ...
Wahlund effect; Regression toward the mean; Multinomial distribution (Hardy–Weinberg is a trinomial distribution with probabilities (, (), ())) Additive disequilibrium and z statistic; Population genetics; Genetic diversity; Founder effect; Population bottleneck; Genetic drift
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.
Another possible cause of genetic divergence is the bottleneck effect. The bottleneck effect is when an event, such as a natural disaster, causes a large portion of the population to die. By chance, certain genetic patterns will be overrepresented in the remaining population, which is similar to what happens with the founder effect. [4]