Genetic drift is the random fluctuation of allele frequencies within a population from one generation to the next. This process is a stochastic mechanism of evolution that occurs purely by chance, particularly impacting smaller populations where chance sampling of gametes can dramatically alter genetic composition. Unlike natural selection, which favors alleles that confer a survival advantage, drift is independent of an allele's fitness consequence. The effects of drift can lead to the random fixation of some alleles and the loss of others, potentially resulting in a decrease in overall genetic variation within the population. The magnitude of genetic drift is inversely proportional to the effective population size, meaning that small populations are subject to much stronger and more rapid changes in allele frequencies compared to large ones.