Your history professor is interested in genealogy and tells your class that, on his mother’s side, he is descended from the original Amish population, a religious and insular group of people in Pennsylvania who tended to marry within their social circle. He also notes that many members of his extended family have the condition polydactyly, an extra finger or toe. The high frequency of polydactyly in your professor’s ancestry is an example of in the Pennsylvania Amish.

Genetic Drift

Explanation

Genetic drift is a mechanism of evolution in which frequencies of allele change in a population due to sampling error.It occurs in all population of any size,but its effect is strongest in small population.

Once genetic drift begins,it will continue until the involved allele is either lost or is the only allele present in a population at a particular locus.

cancer   is   essentially   uncontrolled   mitosis   of specialized cells

the correct answer is:

a population changes in response to a change in the environment.