What is genetic drift?

Genetic drift refers to the random changes in allele frequencies in a population, which can significantly affect genetic diversity over time, especially in small populations. This process occurs due to chance events that can lead to some alleles becoming more or less common purely by random sampling of organisms, rather than through natural selection.

For example, if a natural disaster randomly eliminates a portion of a population, the alleles carried by the survivors will determine which traits are passed on to the next generation, potentially altering the genetic makeup of the population without any environmental influence or selection pressure. This randomness is a key aspect of genetic drift and differentiates it from mechanisms like natural selection, which are non-random and driven by environmental factors.

Understanding genetic drift is essential because it highlights how populations can evolve differently even when under similar environmental conditions, particularly when small population sizes lead to pronounced drift effects that can result in increased inbreeding and loss of genetic variation.