Selection in Action
One concept-oriented software module is "Selection in Action," a Hypercard
stack which, along with a physical population model of colored beads on felt, allows
students to investigate the effects of natural selection on different populations.
Labs which involve students acting as "predators" on some "prey"
population (beans, paper chips, etc.) are common (Fifield & Fall, 1992), but
have traditionally had one of two drawbacks: either the organisms must reproduce
asexually, or students must be able to calculate gene frequencies for subsequent
generations, something which we did not feel was necessary for our nonmajors. More
importantly, most such labs are simple demonstrations, allowing little opportunity
for students to experiment. "Selection in Action" not only does the work
of calculating gene frequencies based on data students enter, it presents situations
which challenge students to create and test hypotheses about the patterns of change
they observe. The program presents a series of "planets" whose populations
have different underlying mechanisms of heredity and variability. Students, unaware
of these differences, must make observations, generate hypotheses, and design tests
in order to construct explanations for what they observe. In this way, the activity
effectively confronts students' misconceptions about the role of heritable variation
in evolutionary change, and allows them to explore the effects of environment and
population size in different situations.
Students enter their data into a spreadsheet-like interface. Students can not only enter data they have gathered by "preying" on their bead models, they can quickly test hypotheses by entering "fake" data, killing off all of one phenotype or even two phenotypes. Another feature also allows users to enter the same data repeatedly over a number of generations with one command, making it faster and easier to see emerging patterns. A fully customizable graphing package is also included.
The instructor can edit problem characteristics or create completely new problems,
an option which is password-protected.
A beta-test version of Selection in Action is available; please contact
for more information.
Download materials for concept
activities
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