University of Washington, Seattle

BIOLOGY 180

RQ13-Mutation Drift

1)What does it mean to say that an allele is “fixed”?

2. What does it mean to say that an allele is “lost”?
3. Drift is caused by random sampling error or other chance events. What is another name for this phenomenon?
4. Why is genetic drift aptly named?
5. Which of the following will NOT cause genetic drift?

Sea stars shed their gametes into water. In one population, sperm with certain alleles are faster and much more likely to fertilize eggs.

A female spider floats to the top of Mount St. Helens and lays eggs, starting a new population.

A devastating disease sweeps through a population, leaving just a few individuals.

Sea stars shed their gametes into water. When currents are strong, only a few sperm and eggs combine to form zygotes.

6. Which of the following is NOT true of genetic drift?

It increases genetic variation in populations.

It occurs in every population, in every generation. It can lead to random fixation or loss of alleles.

It is more pronounced in smaller vs. larger populations.

7. What does it mean to say that many mutations are deleterious?
8. Which of the following is one of the most important effects of mutation?
9. What does it mean to say that mutation is the “ultimate source of genetic variation”?
10. Which of the following evolutionary mechanisms (or “forces”) introduces a random component into evolution?
11. Which of the following introduces a non-random component to evolution?
12. In the graph in Figure 23.17, why did the "jumps" occur?