Learning Evolution in the "Lecture" Room: Using Post-It? Notes Size Variation to Learn about Population Frequency Distributions

 

Tested Studies in Laboratory Teaching, 2015, Volume 36

Lawrence S. Blumer

Abstract

One of the key underpinning concepts for learning how evolution occurs, is the mathematical and graphical description of populations as frequency distributions of individual phenotypes. Phenotypic variation, regardless of its cause (environmental or genetic) is best described in terms of a frequency histogram that is generally abbreviated by simply drawing the shape of the histogram across the range of the variation to be described. A frequency histogram of the existing phenotypic variation is necessarily the starting point for describing how a population may change as a consequence of natural selection, or any other cause for evolutionary change (mutation, genetic drift, or migration). Consequently, when students do not conceptualize the smooth curve of a frequency distribution as the actual representation of the numbers of individuals exhibiting each form (or categories) of a trait, subsequent discussions on how natural selection causes populations to change are undermined. An in-lecture activity using Post-It® Notes of different sizes permits students in small groups to quickly and easily create population frequency histograms, calculate population trait means, and evaluate the effects of selection. This activity takes very little time away from lecture and is very inexpensive. However, this activity makes population frequency histograms more concrete, and permits students to make the link between the shape of their Post-It® Note histograms and the more abstract smooth line frequency distributions that are used to describe the responses of populations to natural selection.

Keywords:  Natural Selection, evolution game, frequency distributions

University of Oregon (2014)