Natural Selection: A Simple Model of Selection in a Variable Environment

 

Ketcham, R. B.

Tested Studies in Laboratory Teaching, 2010, Volume 31

Abstract

This activity is derived from the early (1981, Proceedings Volume 2) ABLE lab by James Waddell called Ecology: Predator-Prey Simulation. Our derivation keeps the original ecological interaction and adds evolutionary consequences. Students act as predators who hunt for prey items in a tabletop arena. The arena, made of aquarium stones and confetti, comes in light-colored and dark colored versions. The prey population starts as an equal mixture of light- and dark-colored beans; the proportions of the mixture change as student-predators hunt through multiple rounds of foraging and the prey reproduce. We chose beans and adjusted the composition of the aquarium stones so our students typically see directional selection in each arena, which we decided was the most desirable outcome for our freshman-level non-majors’ lab. In other contexts the general setup would allow students to explore the effects of manipulating these variables on their own. Our students find this to be a very engaging group activity, as was the original Waddell lab. The activity has a remarkable parallel in the ecological genetics of the rock pocket mouse in Arizona, and a wonderful video of Sean Carroll explaining natural selection of coat color in the rock pocket mouse can be shown at the end of the lab.

Keywords:  evolution, natural selection, Predator-prey interaction

University of Delaware (2009)