Teach the Earth > Paleontology > Teaching Activities > In-class Exercise: Sources of Variation in Populations

In-class Exercise: Sources of Variation in Populations

Jack D. Farmer
Arizona State 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: Jun 16, 2009


Students identify sources of morphological variation (genetic, ontogenetic, sexual, and ecophenotypic differences) among the individuals of populations for three different species, one of which is colonial.

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GLG 460 Introduction to Paleontology is a required course for students majoring in the geological sciences and an elective course for biology students. Graduate credit is offered upon enrolling in GLG 590 Paleontology. (Requires additional research project assignments for graduate credit).

Skills and concepts that students must have mastered

Basic biology or historical geology

How the activity is situated in the course

This project is offered the second week of the course and provides a basic foundation for students to know how to look at fossils to extract the morphological information they contain. Understanding sources of morphological variation in populations is considered foundational for all subsequent topics in the course.


Content/concepts goals for this activity

Understand the sources of morphological (and by extension, behavioral) variation among the individuals of a population and the role that such variation plays in adaptation and evolution.

Higher order thinking skills goals for this activity

Observation and critical evaluation to select between competing explanations.

Other skills goals for this activity

Creating concept sketches, detailed visual observation and comparison. Presenting ideas orally within a group.

Description of the activity/assignment

To prepare for this in-class exercise, students read relevant background material in their textbook and then hear a lecture about sources of variation in populations. Students then form small groups (5 individuals per group) and spend time examining specimens sampled from natural populations of three species. They make sketches and discuss the different types of morphological variation seen, then assign different components of the observed varation to the following sources: Genetic, ontogentic, sexual and ecophenotypic.

Determining whether students have met the goals

Groups report out to the larger group, then turn in their written responses, which are in turn evaluated by the instructor.

More information about assessment tools and techniques.

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