Darwin's Finches and Natural Selection

By Cheryl A. Heinz, Eric Ribbens

Abstract

In this "clicker case," students learn about natural selection through the research of Peter and Rosemary Grant and colleagues on the finches of the Galapagos Islands. Students are presented with data in the form of graphs and asked to determine what is happening to a population of finches as the changing environment produces changes in the shape of the finches' beaks. This case is suitable for any size course in introductory biology, ecology, or evolution, and does not require any pre-requisite knowledge of evolution or natural selection. The case consists of a PowerPoint presentation (~4.5MB) punctuated by questions that students answer in class using "clickers." It can be adapted for use without these technologies.

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Date Posted

09/16/2008

Overview

Objectives

Understand that natural selection is a mechanism of evolution that requires heritable variation and differential survival and/or reproduction.
Realize that evolution by natural selection can be observed within short periods of time.
Develop basic graph reading skills.
(Optional Epilogue): Realize that the advantageousness of a trait changes as the selective environment changes.

Keywords

Natural selection; finch; finches; birds; beak depth; beak size; beak shape; Galapagos Islands; microevolution; evolution; graph reading; Rosemary Grant; Peter Grant; Charles Darwin

Subject Headings

Biology (General)

Botany / Plant Science

Ecology

Evolutionary Biology

EDUCATIONAL LEVEL

High school, Undergraduate lower division

FORMAT

PDF, PowerPoint

TOPICAL AREAS

Scientific method

LANGUAGE

English

TYPE/METHODS

Clicker, Interrupted

Teaching Notes & Answer Key

Teaching Notes

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Answer Key

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Materials & Media

Supplemental Materials

This case has an optional epilogue that extends the case (the first item listed below). It is available in the form of a separate PowerPoint presentation (~340KB). It describes evolutionary dynamics over a slightly larger time scale on the islands, and would be appropriate for use in more advanced classes that consider evolutionary dynamics in more depth.

We also list below other supplemental materials that could be used with this case.

Videos

The Origin of Species: The Beak of the Finch
This short film discusses the work of Rosemary and Peter Grant to document the evolution of the famous Galápagos finches by tracking changes in body traits directly tied to survival, such as beak length, and identified behavioral characteristics that prevent different species from breeding with one another. Their pioneering studies have revealed clues as to how 13 distinct finch species arose from a single ancestral population that migrated from the mainland 2 to 3 million years ago. Running time: 15:54 min. Produced by: HHMI BioInteractive.
Beak of the Finch Film With Quiz
An interactive version of the above film, including pause points and quiz questions.