New search
download case
  • Overview
  • Teaching Notes
  • Answer Key
  • Comments/Replies

Cross-Dressing Salmon

Survival of the Sneaky



Author:

Thomas Horvath
Biology Department
SUNY College at Oneonta
horvattg@oneonta.edu

Abstract:

This "clicker case" about female mimicry in spawning salmon was developed for an introductory-level, non-majors biology course to help address one of the most common misconceptions that students have about natural selection, namely, that only the "strong" survive and reproduce. Female mimicry is an alternative male reproductive strategy. As observed in spawning salmon, some males assume certain female characteristics that enable them to remain close to reproducing females without being viewed as competition by more dominant males. Students learn about concepts of natural selection, including overproduction and differential reproductive success, as well as patterns of natural selection. The case is presented in class via a PowerPoint presentation (~3MB) that is punctuated by multiple-choice questions students answer using personal response systems ("clickers").

Objectives:
  • Learn about natural selection: variability, inheritability, and unequal reproductive success.
  • Understand what is meant by Darwinian fitness.
  • Understand the three patterns of natural selection in a population: directional, stabilizing, and disruptive.
Keywords: Female mimicry; satellite strategy; natural selection; fitness; evolution; morphology; phenotype; adaptation; variability; inheritability; reproductive success; directional selection; stabilizing selection; disruptive selection; fish; Salmon
Topical Area: N/A
Educational Level: High school, Undergraduate lower division
Formats: PDF, PowerPoint
Type/Method: Clicker, Interrupted
Language: English
Subject Headings: Biology (General)   Evolutionary Biology   Zoology  
Date Posted: 12/24/09
Date Modified: N/A
Copyright: Copyright held by the National Center for Case Study Teaching in Science, University at Buffalo, State University of New York. Please see our usage guidelines, which outline our policy concerning permissible reproduction of this work.

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 here.

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.

  Download Teaching Notes

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 here.


  Get Answer Key



Name:
Email:
Department:
Institution:
City State:
Comments:
security code
Enter Security Code: