Genetic Drift
imagine tossing a coin 10 times and getting seven heads and three tails. That would seem acceptable, wouldn’t it? However, imagine tossing the same coin 1000 times to get 700 heads and 300 tails. For the same result to happen in such a large sampling size, the coin would seem to be biased.
Similarly, in a very small population of 10 individuals of red and white flowers, the allelic frequencies for red and white fluctuate over generations. As not all plants survive to leave offspring, random change in allele frequencies causes genetic variation to decrease. The random change in the frequencies of alleles and genotypes due to sampling error is called genetic drift.
Genetic drift is the process of change in the genetic composition of a population due to chance, resulting in allele frequencies changing over time.
It happens when a group of organisms within a population have a higher frequency of an allele compared to other groups of organisms. Eventually, the entire population may become homozygous for the allele. The allele is equally likely to disappear.