Genetic drift often thwarts attempts at applying models of natural selection to real populations, because a gene may come to fixation soley because of random effects, and without any advantage in fitness.

The importance of genetic drift in deterrmining evolutionary outcomes becomes greater when populations are small. This Virtual Experiment simulates two alleles at a locus with no selection or dominance, and displays the frequency of one of these alleles until it is either fixed or eliminated from the population. The experiment takes in population size as an input value.