Answer:
Polydactyly in the Amish population is an example of Founder effect
Step-by-step explanation:
Founder effect is defined as loss of genetic variation as it occurs when a new population is formed by small number of individuals that are diverge from the a large population.
Polydactyly is an example of these founder effect that causes formation of extra finger which takes place when a a polydactyly man marry within their own community. As a result,genetic variation does't takes place among them and thus the offspring carry recessive genes which leads to this type of rare genetic disease.