The Amish populations in the United States began with relatively few individuals and have not recruited many newcomers to the population. Today, these Amish populations exhibit a much higher incidence of polydactyly (possessing extra digits) than other American populations. Which mechanism of evolution is likely responsible for this phenomenon

The founder effect

Explanation: The high incidence of polydactyl prevalent among the Amish population could be attributed to the a case of genetic drift called the founder effect. The founder effect occurs when a small population consisting of few people separate from a much large population, just like the Amish population separating from the larger American community. Due to the few composition or small size of the population, the genetic impact or influence on members of the population is usually higher than the effect on the larger population and leading to more rapid spread. The relatively small individuals which make up the Amish population compared to the larger American community is the reason why polydactyl hmis prevent within them and since theere are no newcomers, the trend will likely continue.