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Teaching Section

Bowsher, Alan [1], Donovan, Lisa A [2], Stanger-Hall, Kathrin [3].

The evolution of vasculature: a classroom case study for evolution by natural selection.

Understanding the concept of evolution by natural selection (ENS) is regarded as one of the five core concepts for undergraduate biological literacy by the American Association for the Advancement of Science. At UGA, Introductory Organismal Biology is a degree requirement for life science majors, and ENS is introduced during the first weeks of the semester as a key learning objective.  However, experience shows that while students tend to memorize the components of ENS quite well, they have difficulty applying it to “novel” situations.  To help bridge the gap between comprehension and application, we designed an in-class, interactive case study, implemented in Spring 2014, which addresses common student misconceptions regarding ENS and provides practice applying the concept. The case study was implemented in two class sections (approximately 250 students each), three weeks after students first learned the ENS concept in class. Following three class lessons on the form and function of key traits in plants, the case study begins by providing evidence that vascular plants evolved from non-vascular ancestors 400 million years ago. To understand how this may have happened, the case study takes students to the mid-Silurian, where they discover the first population of plants in which some individuals produce primitive vascular-like cells. The case-study poses a series of questions to guide students through thinking about how these early vascular plants could have appeared and evolved by natural selection from non-vascular ancestors.  By responding to each question, students apply the four concepts of ENS learned previously: heritable mutation, variation in trait phenotypes, differential reproductive success due to trait variation, and change in allele frequencies in the next generation. The case study concludes with discussions of the environment-dependence of ENS, as well as how early vascular plants continued to evolve into complex present-day plants. To provide an opportunity to apply ENS to a “novel” situation on their own, students were required to compose an essay describing how flowering plants evolved from non-flowering ancestors through natural selection. Compared to an analogous assessment in Spring 2013 in which students were required to describe ENS regarding seed evolution, performance improved dramatically in Spring 2014: Following the case study in 2014, over 70% of students enrolled properly explained the four tenets of ENS, while in 2013, only 12% were able. We hope that this case study and assessment may be used as tools in other classrooms to better help students apply the process of ENS. 

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1 - University of Georgia, Department of Plant Biology, 2502 Miller Plant Sciences, Athens, GA, 30602, USA
2 - University of Georgia, Department of Plant Biology, Athens, GA, 30602
3 - University of Georgia, Department of Plant Biology, Division of Biological Sciences, Athens, GA, 30602

natural selection
case study
undergraduate education
biological literacy.

Presentation Type: Poster:Posters for Sections
Session: P
Location: Eyrie/Boise Centre
Date: Monday, July 28th, 2014
Time: 5:30 PM
Number: PTE005
Abstract ID:319
Candidate for Awards:None

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