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J. Phil Gibson
Associate Professor
Department of Biology and Department of Microbiology & Plant Biology
University of Oklahoma
Breeding Belyaev's Pets: Domestication, Evolution, and the Farm-Fox Experiment

This clicker case addresses several important concepts related to evolution. First, it explores artificial selection and selective breeding. Charles Darwin used artificial selection as an example to support his Theory of Evolution by Natural Selection. Belyaev's Fox-Farm experiment is used as an example of a study that used selective breeding as the primary experimental procedure to investigate changes in a lineage. Second, it addresses an interesting observation made by Charles Darwin in The Origin of Species in which he noted how domesticated species also show interesting traits such as drooping ears which seem to be common in domesticated species. The "Farm-Fox Experiment" not only demonstrates how a research team can thoroughly investigate an intriguing question, but also serves as a classic example of elegant experimental design. Designed for use in a large introductory-level biology class, this case study would also be appropriate for smaller classes as well as for upper-level evolution courses.

Exaggerated Traits and Breeding Success in Widowbirds: A Case of Sexual Selection and Evolution

Sexual selection has led to the evolution of interesting traits and behaviors in many animal species. In widowbirds, males undergo a dramatic change in plumage coloration and produce exceptionally long tail feathers during the breeding season. This change in appearance has facets of both intrasexual and intersexual selection. As students work through this interrupted case, they develop hypotheses and propose corresponding experiments. They are then presented with data from actual experiments on sexual selection in widowbirds that they must analyze and interpret. Developed for introductory-level biology students, the case could be adapted for upper-division ecology and evolution courses.

How Many More Thymes? A Case of Phytochemical Defense 

This clicker case addresses several concepts related to the evolutionary ecology of herbivore defenses. A survey of several different studies that investigated chemical defenses in Thymus vulgaris (thyme) gives students the opportunity to develop hypotheses, pose potential experiments, and interpret data to develop a better understanding of not only herbivore deterrence, but also how natural selection can involve different pressures selecting for different phenotypes. The case study incorporates group discussion, analysis of experimental design, and data evaluation as central activities. It can be taught in a single 50-minute class session, an economy that is achieved in part by using a "flipped" approach. Students prepare outside of class by watching several short videos (one of which was made by the author) that teach the basics of herbivore deterrence and abiotic and biotic forces in the environment that can influence plant adaptations. The case study was designed for use in a large introductory-level class, but would also be appropriate for smaller classes or upper-level evolution courses.

Reproductive Isolation in Columbines 

This clicker case uses plant-pollinator interactions in columbines as a biological scenario to teach students about evolution, reproductive isolation, and angiosperm reproduction. The case is based on an approach to evolution education called tree-thinking that emphasizes the construction, interpretation, and evaluation of phylogenetic trees as an approach to addressing biological and evolutionary questions. It also presents basic concepts of structure-function relationships in flowers and how this influences behavior and effectiveness of different pollinators. Designed for use in a large introductory level class, the case could also be used in smaller classes and in upper-level courses. It is appropriate for use in units on evolution, floral biology, or multispecies interactions.