Final answer:
The founding effect occurs when a mutation becomes prevalent within a population after a small group, carrying it, gets isolated. This can result in the rapid fixation of the mutation in the new population, sometimes leading to an increase in the incidence of certain genetic disorders.
Step-by-step explanation:
Genetic variations within a population can arise from mutations or genetic drift. A particular instance of genetic drift that can lead to rapid changes in a population's genetic makeup is the founder effect. This effect occurs when a small subset of a population, carrying a random assortment of alleles, becomes isolated from the larger original population. If the founding individuals possess unique genetic mutations, these mutations can become prevalent in the new population, particularly if the new environment favors the mutated traits or if there's a lack of gene flow to reintroduce other alleles.
One example of the founder effect can be observed among the Amish, where certain genetic diseases are more common due to the limited gene pool of the original settler population. Similarly, the Afrikaner population of Dutch settlers in South Africa has an elevated occurrence of Huntington's disease and Fanconi anemia thanks to the founder effect. In these scenarios, certain alleles—including deleterious mutations—can become fixed in the population, leading to a higher incidence of certain conditions.