What is Genetic Drift?

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Genetic drift, which is also called allelic drift, refers to the change in terms of the frequency of an allele or gene variant in a particular population because of random sampling. The alleles in a child are a sample of the parents’ alleles and probability has an influence on whether a particular person will survive and reproduce.

The concept of genetic drift is an essential process related to evolution, which results in alterations in the allele frequencies as time passes. Genetic drift may also reduce genetic variation by causing gene variants to completely disappear.

According to the Hardy-Weinberg principle, the allele frequencies within large populations are unchanging from a generation to the next one, except if the equilibrium is interfered with genetic mutation, migration, and selection. When it comes to finite populations, there are no new alleles obtained from the random sampling of the alleles that are carried on to the next generation. However, this random sampling can lead to the disappearance of an existing allele. Since increase or decrease in allele frequency affects the allele distribution, and because random sampling can eliminate, but not substitute an allele, genetic drift can also cause genetic uniformity in specific populations.

Unlike natural selection, which involves making gene variants more or less common based on reproductive success, the alterations that result from genetic drift are not influenced by adaptive pressures or environmental factors.

The impact of this evolutionary process is considered to be greater in small populations compared to bigger populations. Scientists have debated about the importance of genetic drift, in comparison with the natural selection. According to Ronald Fisher, genetic drift plays the least significant role in the process of evolution, and this idea became the most prevalent view for several decades. However, Motoo Kimura proposed the neutral theory of molecular evolution in 1968, which asserts that majority of the changes with genetic material result from genetic drift.

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