Allele frequencies in a gene pool may shift randomly and by chance this random shift is called as "Genetic drift".
Step-by-step explanation:
A shift in the occurrence of an established gene variant within a population due to spontaneous species sampling is understood as a "Genetic drift".The offspring alleles are a composite of those within the parents and opportunity has a key role in deciding whether or not a given person lives and reproduces.
Genetic drift contributes to the retention of populations of the alleles or genotypes. The key difference is that frequencies in genetic drift alleles alter by chance, while frequencies shift by differential reproductive success in natural selection allele.