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Avril M. Harder
Ph.D. Candidate
Department of Biological Sciences
Purdue University
Fish Out of (Salt) Water: Adaptation of an Ocean-Going Fish to Freshwater Environment

This interrupted case study is based on a journal article that describes the rapid adaptation of a population (in this case, steelhead trout) in response to a shift in environmental conditions despite genome‚Äźwide reductions in genetic diversity. First, students learn the basics of natural selection and explicitly link phenotype to fitness as well as fitness to changes in genotype. The discussion then shifts to the evolution of steelhead trout as a result of relocation from salt to freshwater. Students develop hypotheses of expected genomic changes and cultivate skills in interpreting genomic data. The case focuses primarily on population response to changes in habitat, and as such is appropriate for a class focused on response to local habitat changes (e.g., salinity changes in aquatic systems). The case is designed for evolution, ecology, or genomics courses primarily comprised of biology (or related discipline) majors.

Peppered Moths and the Industrial Revolution: Barking up the Wrong Tree?

This interrupted case study was written for students to gain a better understanding of evolutionary concepts and principles as they develop their skills in hypothesis creation, experimental design, and critical analysis of experimental assumptions. These skills are taught using a classic example of rapid adaptation: evolution of peppered moths in response to pollution-induced environmental changes. Students begin with a basic background to the peppered moth system, and then identify and evaluate specific assumptions of the methodology. Students also become familiar with the concept of selection and how this can be quantified. Finally, students are asked to apply these concepts of selection to design a novel experiment. Although the case has broad appeal, it was originally designed for evolution or ecology courses primarily comprised of biology majors.