Random Walks, Evolutionary Trends, and Branching Models of Diversification

Thomas Olszewski

Texas A&M University

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- Scientific Accuracy
- Alignment of Learning Goals, Activities, and Assessments
- Pedagogic Effectiveness
- Robustness (usability and dependability of all components)
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Initial Publication Date: May 12, 2009 | Reviewed: November 3, 2013 (see revision history: 2 events)

Summary

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.

Extinction and Diversity | College Introductory, College Lower (13-14), College Upper (15-16)

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Context

Audience

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.

Goals

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.