A) A textbook definition would be that genetic drift is: a random change in allele frequency caused by a series of chance occurences that cause an allele to become more or less common in a population. In layman's terms, this means that genetic drift happens when luck makes the genetic pool of the population to deviate from what is expected.
B) The cause for this genetic drift is the aformentioned couple. Because amish communities are small and they select partners from their community, having even a couple of carriers of alleles in a community can make the allele freuency much larger than expected; for example, if the community was 100 persons, the percentage would be in the order of 1%, still much larger than the general population. Thus, the cause here is that a small population had a couple of carriers.
C) Sexual reproduction leads to a mixing of alleles from both mother and father and helps diversity. When a population is isolated, the gene pool is fixed and no new genes can come in, reducing diversity. Also some people that have an allele might die, hitting diversity even more. Finally, having a small population creates a strong pressure in some circumstances that leads to elimination of some traits and diversity.
Answer:
Please see below
Explanation:
Adapting to the surrounding environment is a critical part of surviving and, eventually, evolution. Take mice as an instance. Their coat color plays a major role in allowing to go undetected from potential predators if they are able to blend in well with the surrounding environment. Mice with a coat color that makes them stand out will be easily preyed on. Hence, those who have <u><em>adapted</em></u> to their environmental conditions will live to pass on their genes. This phenomenon is known as selection pressure.
Which of what? I need more information to decipher that.
