Darwin's Finches and Natural Selection
Department of Biology
Department of Biological Sciences
Western Illinois University
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.
- 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.
KeywordsNatural selection; finch; finches; birds; beak depth; beak size; beak shape; Galapagos Islands; microevolution; evolution; graph reading; Rosemary Grant; Peter Grant; Charles Darwin
Topical AreasScientific method
Educational LevelHigh school, Undergraduate lower division
Type / MethodsClicker, Interrupted
Subject HeadingsEvolutionary Biology | Ecology | Biology (General) | Botany / Plant Science |
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.
Click-and-Learn: Sorting Finch Species
Data Point Activity: Effects of Natural Selection on Finch Beak Size
Evolution in Action: Data Analysis
Beaks As Tools: Selective Advantage in Changing Environments
Natural Selection and the Evolution of Darwin's Finches
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The following video(s) are recommended for use in association with this case study.
- 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.