Genetic Drift

In the basic lab, student teams set up two islands composed of equal proportions of genotypic alleles. In this simulation the islands will be bowls, one large and one small.  Each bowl will be populated with beans of the same shape and size, but of different colors.  Students will blindly sample half of the beans on each island to reproduce and the non-reproducing beans are eliminated.  After students have recorded the number and proportion of alleles in each new population, they blindly resample each population again and again record the new proportion of alleles left on each island.  After five iterations, the students can stop and compare the initial vs. final proportions of alleles left on each island.  Genetic drift should have occurred much more dramatically on the small island than on the large island. Great teacher notes and directions, good student directions, and the inclusion of analysis of tables and graphs to develop conclusions makes this a great web site. This simulation builds student understanding of processes other than natural selection that can influence evolution.

Microsoft Office document icon Genetic Drift Lab

Lesson Variations

Blooms taxonomy level: 
Analyzing
Extension suggestions: 
  • For an extension of the fundamentals of genetic drift, have your students simulate a bottleneck or founder event by starting with a large population of known proportions of alleles (known number of beans and their colors) and then randomly sample a small number of those beans from the initial population to begin a new population that you can let grow.  After four or five generations of growth, you can compare the proportion of alleles in the new population vs. the initial population.

Helpful Hints

Materials:

  • Big Island Bowl
  • Little Island Bowl
  • Bean Organisms: Brown, Red, White, Pink, and Black-Eyed
  • Data Table
     

References

Contributors: 
Dale Rudolph
Originator: 
Ayers Institute for Learning & Innovation