Shooting the Poop
More than Good Housekeeping?
Author(s)
Abstract
This group-based case study is based on research by Dr. Martha Weiss using silver-spotted skipper caterpillars (Epargyreus clarus (Lepidoptera)). These insects perform the unusual behavior of flinging their frass (excrement) great distances away from their leaf shelters. This charismatic study system, besides being appealing to students, has the advantage of having several plausible alternative adaptive hypotheses to investigate. After viewing a brief PowerPoint presentation that introduces the perils of caterpillar life and a video demonstrating their unusual behavior, students brainstorm hypotheses and experiments to test them. Students then receive a set of datasheets and questions that guide them to an understanding of the actual experiments that Weiss conducted. The conclusion of the case provides an opportunity to discuss the difference between statistical and biological significance, a distinction often neglected. This case was developed for introductory-biology major undergraduate students, but can also be used in any undergraduate course involving the evolutionary concepts of adaptation and fitness.
Objectives
- Review adaptation, fitness, and selective pressures.
- Review the role of adaptation in evolutionary processes.
- Know how to measure fitness and/or fitness proxies.
- Formulate hypotheses about adaptive traits.
- Design experiments to evaluate hypotheses.
- Interpret figures and analyze statistical reports to evaluate the validity of proposed hypotheses.
- Determine whether statistical significance equates to biological significance.
Keywords
Adaptative hypotheses; biological significance; experimental design; fitness measures; anal comb; defecation; Epargyreus clarus; frass; faecal pellets; Hesperiidae; leaf-roller; Polistes; shelter-builder; WeissTopical Areas
N/AEducational Level
Undergraduate lower division, Undergraduate upper divisionFormat
PDF, PowerPointType / Methods
Directed, DiscussionLanguage
EnglishSubject Headings
Ecology | Evolutionary Biology |
Date Posted
3/8/2016Teaching Notes
Case teaching notes are password-protected and access to them is limited to paid subscribed instructors. To become a paid subscriber, begin the process by registering.
Teaching notes are intended to help teachers select and adopt a case. They typically include a summary of the case, teaching objectives, information about the intended audience, details about how the case may be taught, and a list of references and resources.
Supplemental Materials
The PowerPoint presentation below introduces caterpillar life, shelter building activity, and frass flinging behavior.
caterpillars.pptx
Answer Key
Answer keys for the cases in our collection are password-protected and access to them is limited to paid subscribed instructors. To become a paid subscriber, begin the process by registering.