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VOLUME 3: Table of Contents TEACHING ISSUES AND EXPERIMENTS IN ECOLOGY
EXPERIMENTS

What Happens

Students observe galls on willow leaves, and begin their investigations in teams by collecting data to test the instructor-posed hypothesis that the number of galls per leaf varies among willow trees. This step gives students more guidance, allows them to practice sampling on a question they will discuss in class but won’t include in their graded assignment, and gives them a chance to view a number of galls and leaves to get a better sense of the study system and the typical pattern that herbivory varies among leaves and among plants (due to differences in plant chemistry, physical traits, environmental traits, etc.). Student teams then choose among several instructor-directed questions (such as whether female sawflies oviposit independently of other oviposition events, whether galls on leaves with other galls are less successful than single galls on leaves, and whether leaf-chewing herbivores select leaves independently of galls), or pose their own hypothesis. Instructors may assign these randomly to ensure that each hypothesis is tested by at least one team, or briefly discuss why each hypothesis might be interesting to test. More motivated teams might be challenged to formulate their own question based on their preliminary observations at the site. For example, they may notice that trees vary in size/age, or in distance to surface water, or that not all galls are the same size. Instructors can capitalize on these observations by encouraging students to ask how these variations might influence gall distribution or success. Once teams select a hypothesis, they then collect data to test the hypothesis, analyze their data, and prepare a formal oral report on their investigation.

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Lab Objectives

At the conclusion of this lab, students will be able to:

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Equipment/Logistics Required

Equipment:

Logistic Requirements:

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Summary of What is Due

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Keyword Descriptors

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