Teach the Earth > Paleontology > Teaching Activities > Random Walks, Evolutionary Trends, and Branching Models of Diversification

Random Walks, Evolutionary Trends, and Branching Models of Diversification

Thomas Olszewski
Texas A&M University
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This activity was selected for the On the Cutting Edge Reviewed Teaching Collection

This activity has received positive reviews in a peer review process involving five review categories. The five categories included in the process are

  • Scientific Accuracy
  • Alignment of Learning Goals, Activities, and Assessments
  • Pedagogic Effectiveness
  • Robustness (usability and dependability of all components)
  • Completeness of the ActivitySheet web page

For more information about the peer review process itself, please see http://serc.carleton.edu/NAGTWorkshops/review.html.

This activity has benefited from input from faculty educators beyond the author through a review and suggestion process. This review took place as a part of a faculty professional development workshop where groups of faculty reviewed each others' activities and offered feedback and ideas for improvements. To learn more about the process On the Cutting Edge uses for activity review, see http://serc.carleton.edu/NAGTWorkshops/review.html.

This page first made public: May 12, 2009


Students are exposed to the concept of random walk and how stochastic processes can be applied to constrain interpretation of diversity trends through geologic time.

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upper-level undergraduate course for geology majors; has been used for introductory and historical geology

Skills and concepts that students must have mastered

plotting data

How the activity is situated in the course

This is a lab exercise that complements lectures on the subject in class.


Content/concepts goals for this activity

diversity trends
random walks and the concept of stochastic processes
confidence intervals

Higher order thinking skills goals for this activity

Gathering and analyzing data and using a stochastic process to test alternative hypotheses/interpretations.

Other skills goals for this activity

Description of the activity/assignment

In this exercise, students use random numbers drawn from a telephone directory to create a series of phylogenetic trees based on the assumptions of constant probability of origination and extinction per lineage through time. They use these trees to derive diversity trends and compare their model results to a real phylogeny of echinoids to test the model assumptions. They interpret any deviations and propose means of testing their ideas.

Determining whether students have met the goals

The students hand in answers to a series of questions on the lab and the concepts are further tested on class exams.

More information about assessment tools and techniques.

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