Butterfly Hunt
The Role of Density Dependence in Batesian and Müllerian Mimicry
Author(s)
Department of Biological Sciences
University of Denver
robin.tinghitella@du.edu
Abstract
This case study uses an interactive activity to illustrate density dependence in ecology classes. We developed a "hunt" using paper butterflies with warning signals on the upper side of the wings and symbols that indicate if a butterfly is noxious underneath the wings. Butterflies are distributed in four different patches with varying densities of noxious and palatable butterflies, simulating Batesian or Müllerian mimicry. Students can catch as many butterflies they want for a period of time, but if they catch more than three noxious butterflies they are out of the game. After the activity, students calculate the survival rate of each type of butterfly in each patch and discuss the implications of density and warning signals according to their results. Students then answer questions and build graphs using the data from the activity and knowledge from the class and the discussion. With this case study, students will be able to understand negative and positive density dependence, as well as predation, learning, and convergent evolution, while recalling or being introduced to Batesian and Müllerian mimicry.
Objectives
- Review numerical and functional responses.
- Build graphs.
- Define Batesian and Müllerian mimicry.
- Explain and distinguish between negative and positive density dependence.
- Discuss convergent evolution and learning.
- Describe how predation can lead to convergent evolution in warning signals.
Keywords
density dependence; mimicry; predation; aposematism; warning coloration; numerical response; functional response; fitness; convergent evolution; butterfly;Topical Areas
N/AEducational Level
High school, Undergraduate lower division, Undergraduate upper divisionFormat
PDF, PowerPointType / Methods
Demonstration, Directed, DiscussionLanguage
EnglishSubject Headings
Ecology | Biology (General) | Evolutionary Biology |
Date Posted
11/13/2017Teaching Notes
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Supplemental Materials
The PDF flie below contains "butterflies" for the hunt; the teaching notes explain how many to print out. The PowerPoint presentation below is used to structure the class discussion and to record results of the hunt.
Butterflies (butterfly_hunt_sup.pdf)
PPT Presentation (butterfly_hunt_sup.pptx)
Answer Key
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Comments
Kathryn Swanson
swan1959@umn.edu
Biology
Concordia - St. Paul
St. Paul, MN
11/20/2017
Overall, I liked this activity, but my students quickly recognized the difference between noxious wings (solid black ovals) and palatable mimics wings (solid black ovals ringed with gray). This made the results for patch A and patch B almost identical since after the students “ate” the regular butterflies they systematically ate all the palatable mimics. -----------------------------
12/05/2017
Authors’ Reply:
A couple of factors may influence the results experienced in class.
1. It is possible that there are differences across printers that make the difference between models and mimics more obvious. So an instructor might have to adjust contrast between black and gray when printing to account for differences among printers.
2. An instructor can also shorten the time given for the hunt. In class this year we ran the activity by giving the students only a minute to “hunt.” Teachers can also observe how quickly students are over-harvesting their patches and end the hunt at any time if students are hunting too quickly.
We hope these suggestions are helpful for future instructors.
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