Genetic Drift
Explanation:
Genetic drift is a mechanism of evolution in which allele frequencies of a population change over generations due to chance or sampling error. Genetic drift occurs in all populations of non-infinite size, but its effects are strongest in small populations. This process may result in the loss of some alleles (including beneficial ones) and the fixation, or rise to 100% frequency, of other alleles. It also have major effects when a population is sharply reduced in size by a natural disaster (bottleneck effect) or when a small group splits off from the main population to found a colony (founder effect).
