Survival of the Fittest and the Peppered Moth
Science Department Chair Ben Hatch recently challenged his Applied Biology students to better understand Darwin’s Theory of Natural Selection and how it applies to the peppered moth. Through a simulation that required teams to take on roles of “predator” and “prey,” students learned about the importance of coloration in avoiding predation, understood the link between environmental and organism changes, and examined how natural selection causes populations to change.
“Industrial melanism is a term used to describe the adaptation of a population in response to pollution,” shares Mr. Hatch. One example of rapid industrial melanism occurred in populations of peppered moths in the area of Manchester, England from 1845 to 1890. Mr. Hatch adds, “Before the industrial revolution, the trunks of trees in the forest were light grayish-green due to the presence of lichens. As the industrial revolution progressed, the tree trunks became covered with soot and over a period of 45 years, the dark variety of the peppered moth became more common than the light.” This is, of course, due to the higher survival rate of the dark moth because of its ability to blend into the soot-covered trees.
To put this into context, Mr. Hatch asked his students to simulate a predator-prey relationship using cutouts of white paper and newspaper, a timer, and forceps. Using the forceps to simulate a bird’s beak, students were allowed 15 seconds to pick up as many moth cut-outs as possible against similar and contrasting backdrops. After recording their data, students saw the direct link between coloration and blending and survival rates, and consequently the reason the dark peppered moth population outpaced that of the light.
This lab is part of Mr. Hatch’s unit on Evolution, which examines the genetic changes that occur in constantly changing environments, and studies the amazing diversity of life on earth.