Question

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 gene flow convergent evolution natural selection

Explanation:

The founder effect occurs when a small group starts a new population, leading to reduced genetic diversity. The Amish began with few individuals, so rare traits (like polydactyly) in the founders become more common. Gene flow involves new genes from outside, which the Amish lack. Convergent evolution is unrelated, and natural selection isn't indicated here.

Answer:

the founder effect