How Many More Thymes & Herbivore Defense
By Sheryl Konrad and Angela Dassow
This week’s featured resource is an adaptation of:
J. Phil Gibson. July 2015, posting date. How many more thymes? A case of phytochemical defense. National Center for Case Study Teaching in Science.
This adaptation uses the videos and case study slides associated with the original resource to teach students the evolutionary ecology behind herbivore defenses in plants. Due to the extended course time that was available, the authors of this adaptation were able to make several exciting additions to the original material:
1. In-class discussion of videos - Students watch “Don’t Eat the Plants” and “Mediterranean Vegetation - How Plants Survive” outside of class to prepare for the discussion.
2. Thyme plant observations - Students use detailed observations of six different thyme phenotypes to predict chemotype in thyme plant varieties.
3. Small group work - Students read a phys.org news article summary of peer-reviewed research demonstrating ecological pleiotropy in Nicotiana plants, which are pollinated by Manduca sexta moths that also lay their eggs on the plant's leaves, thereby challenging the plant with herbivory. Research shows that terpenes are differentially regulated in Nicotiana flowers and leaves based on environmental cues, and students are asked to consider how and why this happens. Students also have the opportunity to practice developing hypotheses, posing potential experiments, and planning realistic data collection procedures.
This adaptation was used in a lower-level biology majors course. The course had a studio format - combining lab and lecture - and had students meeting three times a week for 2 hours and 20 minutes. Over the course of one week, each class session devoted ~35-45 minutes to these activities.
Konrad, S., Dassow, A. (2019). How Many More Thymes & Herbivore Defense. Making the Case, QUBES Educational Resources. doi:10.25334/Q4FN0X