Student Exploration: Natural Selection
Vocabulary: biological evolution, camouflage, Industrial Revolution, lichen, morph, natural
selection, peppered mo... [Show More] th
Prior Knowledge Questions (Do these BEFORE using the Gizmo.)
The peppered moth (Biston betularia) is a common moth
found in Europe, Asia, and North America. It is commonly
found in two forms, or morphs: a dark morph and a light,
speckled morph. Birds are a frequent predator of the
1. Which morph do you think would be easier to see on a
dark tree trunk? light-colored
2. Which morph do you think would be easier to see on a
light tree trunk? The dark
The Natural Selection Gizmo™ allows you to play the role of
a bird feeding on peppered moths. The initial population of
40 moths is scattered over 20 tree trunks. Click on moths to
capture them. Click the Next tree button (or the spacebar
on your keyboard) to advance to the next tree.
1. Check that LIGHT TREES is selected. Click Play ( ),
and hunt moths for one year.
A. How many dark moths did you capture? _5 dark
B. How many light moths did you capture? 0 light
moths were captured
How many moths can you find?Get the Gizmo ready:
• Click Reset ( ).
• Check that the LIGHT TREES tab is selected.
C. Camouflage is coloring or patterns that help an organism to blend in with the
background. Which type of moth is better camouflaged on light bark? light colored
2. If a forest contained mostly light-colored trees, which type of moth would you expect to be
most common? light-colored moth would be most
Introduction: Before the 19th century in England, the air was very clean. The bark on trees was
usually light in color. Abundant lichens growing on tree trunks also lightened their appearance.
Question: How does the color of a peppered moth affect survival?
1. Predict: Over time, what will to happen to the populations of light and dark moths on light
trees? light moths would increase while the dark moths would begin to
2. Experiment: Click Play and hunt peppered moths on light tree trunks for five years. In each
year, try to capture as many moths as you can. Note: You can use the spacebar on your
keyboard to quickly advance to the next tree.
After 5 years, select the TABLE tab and record the percentages of each moth type. (Note:
The table shows current populations of each moth, not the number of captured moths.) [Show Less]