Definition of Founder Effect
The founder effect is the change in the frequency of allele when a small group of individuals get separated from the larger group. This small group of individuals move to a new place and establish a colony of their own there. Hence, genetic variation is reduced.
The new population that is formed shows variations from the original population in terms of both genotype and phenotype. The new population may have more of a certain type of gene or less of a certain type of gene due to which the characteristics (phenotype) like height, weight, etc. are also changed. New species also emerge as a result of the founder effect