Skip to Content

Testing for Grazer Adaptation to Toxic Algae


Michael B. Finiguerra
Department of Ecology and Evolutionary Biology
University of Connecticut: Avery Point Campus
Hans G. Dam
Department of Marine Sciences
University of Connecticut
David E. Avery
Department of Arts and Sciences
Maine Maritime Academy


The intent of this interrupted case study is to present a clear example of both the scientific method and evolutionary adaptation in a model system consisting of marine grazers (copepods) and toxic prey (phytoplankton). Briefly, a certain toxic phytoplankton is found only north of Long Island Sound in the United States; however, populations of their copepod grazers are found more extensively from Maine to Delaware. Students will consider whether exposure to toxic phytoplankton among northern grazer populations has led to greater fitness compared to those populations that have never experienced the toxin (i.e., southern populations), and whether the evidence supports adaptation or plasticity. Students will also discuss the broader impacts of adaptation to toxins in marine food webs. A primary aim is to show students how to go from observation and hypothesis to analysis of data. This activity was originally designed for a second year evolutionary biology or ecology course, but can easily be adapted for the evolution section of a general biology course or an upper-level biological oceanography course.


  • Understand how a set of observations leads to an important and testable scientific question.
  • Generate a testable hypothesis.
  • Develop a detailed experimental methodology to test the hypothesis, with emphasis on controls.
  • Determine if the results presented in the case study support the hypothesis, and why.
  • Identify how answering the question (i.e., testing and supporting the hypothesis) leads to additional related scientific questions.


evolution; toxic algae; common garden; food web; copepods; Long Island Sound; paralytic shellfish toxins; PST; harmful algal blooms; HAB; nitrogen; nutrients; phosphorus; red tides

Topical Areas

Scientific argumentation

Educational Level

Undergraduate lower division, Undergraduate upper division



Type / Methods




Subject Headings

Biology (General)  |   Ecology  |   Evolutionary Biology  |   Science (General)  |   Marine Science / Oceanography  |  

Date Posted


Teaching 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

This optional material from Science Friday provides another nice example of rapid adaptation by a fish.

  How Lake Fish Are Coping With Pollution
  Can The Great Lakes Stay Great?

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.


The following video(s) are recommended for use in association with this case study.

  • The Origin of Species: The Beak of the Finch
    This video from HHMI on the Galapagos Finches provides a great example of natural selection and adaptation and can serve as a useful introduction to this case study. Running time: 16:08 min. Produced by HHMI BioInteractive, 2014.