Question

Populations change over time, especially human populations in the modern era with access to travel. There are a few exceptions to this ever growing pool of genetic diversity. One example can be found in Eastern Pennsylvania where the Amish live. The Amish immigrated from Germany to America in the mid 1700s, and the community was established by an estimated 200 individuals. Due to culture, most Amish marry within the community and due to isolation, many rare genetic mutations persist at a high frequency in the Amish. Which of the following best describes this scenario?

Answer 1

Founder effect — a form of genetic drift. A small group of founders (≈200) carried only a subset of the original population’s alleles; isolation and endogamy let those alleles (including rare ones) reach unusually high frequencies in descendants.