Understanding Evolution: Problem-based discussion
For the instructor:
Pedagogical research indicates that students learn better if they are actively engaged.
The following slides require only a few minutes each and are designed to actively
engage students with lecture material on the topic of evolution through discussion.
Problem-based discussions are a valuable active learning technique that involves
students teaching each other, thus promoting student engagement and learning. In this
technique, the instructor posts a written description of a scientific problem or a
diagram, table, or graph relevant to a topic under consideration. The instructor
provides a list of questions that students should work to answer. Students then spend
5–10 minutes, first thinking individually about the questions in reference to the problem
or figure, and then pair up and take turns explaining their answers to each other and
filling gaps in each other’s knowledge. At the end of the discussion, the instructor can
read aloud the questions, either verbatim or modified to be slightly different, and ask
whether students are confident they could explain the issues to each other. The
instructor may wish to call on students to answer individual questions, or may ask if
the discussion raised any questions they would like to ask in class.
This slideshow is provided by Understanding Evolution (understandingevolution.org)
and is copyright 2011 by The University of California Museum of Paleontology,
Berkeley, and the Regents of the University of California. Feel free to use and modify
this presentation for educational purposes.
Understanding Evolution: Problem-based discussion
Population genetics simulation of drift
1) Explain what is shown on the x- and y-axes.
2) Choose two lines on graph A, one that goes to the top of the graph and
one that goes to the bottom. For each line, explain what the line represents
and how it changes over time. Also, explain what it means when a line
goes to the top of the graph versus what it means when a line goes to the
bottom of the graph.
Understanding Evolution: Problem-based discussion
Population genetics simulation of drift
3) Explain the difference between the simulations that generated graphs A
and B.
4) Why do y-values fluctuate in each graph?
Understanding Evolution: Problem-based discussion
Population genetics simulation of drift
5) In graph A, how many of the trials resulted in a frequency of A = 1.0 and
how many resulted in a frequency of a = 1.0? Why might this occur?
6) The populations represented by graph A and graph B demonstrate very
different behavior. What concept regarding genetic drift does this
illustrate?
Understanding Evolution: Problem-based discussion
Population genetics simulation of drift
7) If one allele were under selection in graph B, how would this graph differ?
8) For each population represented on graph A, would you expect the
population to be in Hardy-Weinberg equilibrium? For graph B?
Understanding Evolution: Problem-based discussion
Population genetics simulation of drift
9) How would each of these graphs differ if starting allele frequencies in
the simulations were not 50/50—for example, if the populations began with
30% A alleles and 70% a alleles? Would drift occur?