Gendrift

Genetic drift

Gendrift is the random change in the gene frequency of a specific allele within a population. Especially in small populations, gene drift is important because alleles can disappear relatively quickly from the gene pool of the population. But the exact opposite is also possible, namely that certain genes suddenly appear extremely frequently in a population, for example after natural disasters, when only a few individuals have survived and many of them carry a previously rare allele in itself.

Example of Gendrift - Founder Effect

In the founding effect, a new population is established by a few individuals. Within this new founder population (P2), the allele frequency (allele frequency) differs from the now isolated (there is no more gene flow between P1 and P2) starting population (P1). This results in significantly lower gene variability because some of the alleles that appear in P1 are not present in any of the individuals of P2. Therefore, the gene pool of P2 consists of a completely different allele composition than P1.

Necessary condition of the founder effect is isolation from the initial population, for example by geographic isolation (see Allopatric speciation)

Example of gene drift - bottleneck effect

The bottleneck effect describes the strong reduction in genetic variability associated with the randomized change in allele frequencies. The bottleneck effect is usually due to an event, such as a natural disaster in which many individuals are killed, sudden geographic isolation from plate tectonics, but also e.g. the drifting of individuals on a still unpopulated island. In all cases, the random selection of individuals for the bottleneck effect is crucial, regardless of their adaptation to environmental factors.

Summary

Gene drift is the random change in the gene frequency of one or more specific alleles within a population

Random events such as natural disasters favor gendrift

The smaller a population, the more likely it is gendrift

The founder effect and bottleneck effect are examples of gene drift