Genetic drift, often called the Sewall Wright effect, after the individual who set forth the idea of hereditary float, is the adjustment in the recurrence of a previous gene variant (allele) in a populace because of impact of random sampling (Barton and Charlesworth, 1984; Masel, 2011). Drift can cause allele fixation in a population. Once an allele is fixed, genetic drift ceases; the allele frequency cannot be changed unless another allele is brought into the populace by means of mutation or gene flow. Although both genetic drift and natural selection affect evolution, genetic drift operates randomly, while natural selection functions in a direction that ensures survival and reproductive fitness of that particular organism (Kimura, 1968). One of the best examples of genetic drift is a genetic bottleneck (Charlesworth, 2009).