What is genetic drift?

Genetic drift is defined as a mechanism of evolution that involves random changes in allele frequencies within a population. This random process occurs primarily in small populations, where chance events can lead to significant fluctuations in allele frequencies over time. For example, if a few individuals contribute disproportionately to the next generation by chance, their alleles may become more common or even fixed in the population, while others may be lost entirely.

This randomness is what distinguishes genetic drift from other mechanisms of evolution, such as natural selection, which operates through non-random processes based on the fitness of individuals. In contrast, genetic drift does not favor any particular allele and can lead to unpredictable changes in the genetic makeup of a population. It highlights the role of chance in evolutionary processes, making it a fundamental concept in population genetics.

In broader context, other concepts mentioned in the other choices do not fit the definition of genetic drift, as they involve structured processes of mating or selection rather than the randomness that characterizes genetic drift.