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A Decision to Branch Out

Evolution and the Domestication of Maize


Dongfang Wang
Department of Biology
Spelman College


In this flipped case study, students use the scientific method to investigate how changes in a few genes have shaped the evolution of maize plant architecture during domestication. To prepare for the case, students first watch a video developed by HHMI BioInteractive to learn the story behind maize domestication and make connections between traits and fitness. In a second video, students learn the vocabulary of scientific methodology, such as independent and dependent variables, correlation, requirement, and sufficiency. In class, students engage in data analysis and discussion focusing on the effects of mutation on gene expression, plant architecture, and the evolutionary fitness of individuals within a population. In addition to training students to use the method of science, the case also reinforces core concepts in evolution, information flow, and structure function. The case is suitable for sophomore-level introductory biology courses and bio-elective courses.


  • Draw conclusions based on experimental data, which includes the ability to identify independent and dependent variables, as well as the difference between correlative, loss-of-function, and gain-of-function evidence.
  • Compare and contrast natural and artificial selection.


scientific method; domestication; plant architecture; gene expression; evolution; corn; maize; branching; teosinte

Topical Areas


Educational Level

Undergraduate lower division, Undergraduate upper division



Type / Methods

Analysis (Issues), Discussion, Flipped, Journal Article



Subject Headings

Evolutionary Biology  |   Genetics / Heredity  |   Molecular Biology  |  

Date Posted


Teaching Notes

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Answer Key

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

  • Popped Secret: The Mysterious Origin of Corn hhmi/
    This video tells the story of the genetic changes involved in the transformation of a wild grass called teosinte into corn. Running time: 17:51 min. Produced by HHMI BioInteractive, 2015.
  • A Decision to Branch Out
    This video explains the use of the scientific method to investigate the genetic changes behind maize domestication. Running time: 5:41 min. Created by Dongfang Wang for the National Center for Case Study Teaching in Science, 2015.