Name: ______Date: ______Per. _____

Genetic Drift Lab

Genetic Drift on Two Different Islands

Question or Problem:

How will genetic drift affect the diversity among the organisms in a population on a small island vs. a larger population on a large island?

Hypothesis (your best educated guess that answers the question or solves the problem) Genetic drift will affect diversity on a small island _____ than a big island because______.

______

DIRECTIONS

1.  PICK with eyes closed (20 from big, 5 from small) which individuals die. Put them in the cemetery (cup).

2.  DOUBLE. For each surviving bead, add a bead of the same color. (Use beads from the cemetery, along with extras if needed.)

3.  COUNT the number of beads left in the bag

4.  RECORD surviving beads in your data table

Island / Color Allele / Year 0 (initial) / Year 1 / Year 2 / Year 3 / Year 4 / Year 5
Small Island / 2
2
2
2
2
Total / 10
Big Island / 8
8
8
8
8
Total / 40

Discussion. Use your graphs and data table!

  1. Fill in the blanks with the appropriate color allele

On the big island, the ______allele increased the most, while the ______allele decreased the most. ______alleles stayed about the same.

On the small island, the ______allele increased the most, while the ______allele decreased the most. ______alleles stayed about the same.

  1. Did the proportion of alleles change more on one of the islands than on the other? If so, then explain why. Use the sentence stem: “The proportion of alleles changed more on the __ Island. This is because ___.”
  1. Did any alleles go extinct on either of the islands? If so, name the alleles and on which island they were lost.
  1. Did any allele completely “take over” (this is called “becoming fixed”) a population? If so, name the allele and on which island it “took over.”
  1. Record class data for year 5 in the table below.

Write color of beads à
Table 1-
Small Island
Table 1-
Big Island
Table 2-
Small Island
Table 2-
Big Island
Table 3-
Small Island
Table 3-
Big Island
Table 4-
Small Island
Table 4-
Big Island
Table 5-
Small Island
Table 5-
Big Island
Table 6-
Small Island
Table 6-
Big Island
Table 7-
Small Island
Table 7-
Big Island
  1. Do you think that if an allele became fixed (took over) the first time you performed the experiment, the same allele would become fixed if the experiment was repeated? Why or why not? Use the data from the table above to support your conclusion.
  1. Do you think that losing alleles will help or hurt the population? Why? Use the stem: “Losing alleles ______the population because______.”
  1. Can you propose any ways that an island could get extinct alleles back into its gene pool? (There are two ways. Name at least one)

An island could get extinct alleles back into its gene pool by ______

  1. Natural Selection and Genetic Drift can both cause populations to evolve over time, but they do it differently. Explain how they're different. Use the stem: “Natural selection and genetic drift are different because natural selection is ______while genetic drift is ______.

10.  Tell me whether you accept or reject your hypothesis, and explain why. (Was your hypothesis supported by the experiment?)