What does genetic drift refer to?

Genetic drift refers to the change in allele frequencies within a population due to random chance events. This concept is particularly significant in small populations, where chance fluctuations can have a larger impact compared to larger populations. When certain alleles become more or less common purely by chance—such as through random mating, the random survival of individuals, or other unpredictable factors—alters the genetic makeup of the next generation.

Unlike natural selection, which involves adaptive changes favoring certain traits that improve survival and reproduction, genetic drift is entirely non-directional and does not necessarily lead to any adaptation. Such drift can result in the loss of genetic variation and can affect evolutionary trajectories, especially in isolated populations. This randomness can lead to significant changes in a population’s genetic structure over time, even if environmental conditions remain constant.

The other choices do not accurately define genetic drift. The first choice refers to artificial selection; the third choice describes natural selection; and the fourth choice pertains to speciation processes rather than the random changes in allele frequencies that characterize genetic drift.