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Cross-Dressing Salmon

Survival of the Sneaky


 

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").

   

Date Posted

12/24/09

Overview

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

  

Subject Headings

Biology (General)
Evolutionary Biology
Zoology

EDUCATIONAL LEVEL

High school, Undergraduate lower division

  

FORMAT

PDF, PowerPoint

   

TOPICAL AREAS

N/A

   

LANGUAGE

English

   

TYPE/METHODS

Clicker, Interrupted

 

 

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