genetic drift

What is genetic drift?

Genetic drift is a process of evolution that occurs when there is a random change in the frequency of alleles (alternative forms of a gene) in a population over time. It is one of the mechanisms by which genetic variation can arise and be lost.

How does genetic drift occur?

Genetic drift occurs due to random sampling errors in the transmission of genes from one generation to the next. In every generation, individuals may produce offspring that do not accurately represent the gene pool of the parent population due to chance events. As a result, certain alleles may become more or less common in subsequent generations.

Types of genetic drift

There are two main types of genetic drift:

  1. Bottleneck effect:

    1. This occurs when a large population is drastically reduced in size, leading to a loss of genetic variation. The surviving individuals may not represent the full diversity of the original population, resulting in some alleles being overrepresented and others being lost.

  2. Founder effect:

    1. This happens when a few individuals from a larger population establish a new population in a different geographic area or habitat. The smaller founding population may have limited genetic variation compared to the original population, leading to differences in allele frequencies.

Effects of genetic drift

Genetic drift can have several effects on populations:

  1. Loss of genetic diversity: Genetic drift can lead to the loss of rare alleles and reduce overall genetic variation within a population.

  2. Fixation or loss of alleles: Due to chance events, certain alleles may become fixed (reach a frequency of 100%) or lost (disappear) in a population.

  3. Increased frequency of harmful alleles: Harmful alleles that were initially present at low frequencies can become more common due to genetic drift, potentially increasing the risk of inherited disorders.

  4. Differentiation between populations: Genetic drift can contribute to the divergence between populations over time, as different chance events occur in each population independently.