One of the original Amish colonies rose from a ship of colonists that came from Europe. The ship’s captain, who had polydactyly, a rare dominant trait, was one of the original colonists. Today, we see a much higher frequency of polydactyly in the Amish population. This is an example of:

natural selection

genetic drift

founder effect

b and c

B and C

Explanation:

When the Amish came to their new home, they were founding a new colony. This is considered a founding effect.

Now, there is another thing to keep in mind, and that is that the Amish are very strict about their custom, for example, the idea of family and identity. This led them to form couples, only among the members who belonged to the community.

As generations go by, genealogical relationships between individuals in the population become closer. This causes some genes, by mere probability, to become fixed (i. e. they are the only ones left in the population). As a consequence of this, the frequency of rare genes increases (polydactyly). This evolutionary process is known as gene drift.