Name: _____________________________________________
Peppered Moth Survey
Skills:
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Graphing and analyzing data
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Describe the importance of coloration in avoiding predation
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Relate environmental change to changes in organisms within an ecosystem
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Explain how natural selection causes populations to change
Materials:
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Sheet of white paper
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White disks (30)
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Black disks (30)
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Sheet of newspaper
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Forceps
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Colored pencils
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Stopwatch
Purpose:
In this lab, you will simulate how successfully predators locate prey in different environments. Then you will
analyze actual data and relate changes in a population of peppered moths with two color variations to changes
in the environment.
Background:
Natural selection, the reproductive success of organisms best suited to their environment, is a driving force in
evolution. Natural selection occurs within populations, which are interbreeding groups of individuals of the
same species. Genetic variation, the alternative types of genes for inherited traits, is one factor in the
reproductive success of certain members of a population. The result of natural selection is adaptation, the
changing of a population so that it is better suited to its environment.
Industrial melanism is the term used to describe the adaptation of a population by the darkening of its
individuals in response to industrial pollution. One example of rapid industrial melanism occurred in populations
of peppered moths, Biston betularia in the area of Manchester, England, from 1845 to 1890. Before the
Industrial Revolution, the trunks of trees in the forest around Manchester were light grayish green due to the
presence of lichens. Most of the peppered moths in the area were light-colored with spots. As the Industrial
Revolution progressed, the tree trunks became covered with soot and turned dark. Over a period of 45 years, a
dark variety of the peppered moths became more common.
Procedure: Part 1 - Simulating Predator-Prey Relationships
1. Work with a partner, and decide which of you will be the “predator” and which will keep time
2. Place a sheet of white paper on your lab table. If you are the time keeper, place the white and black
disks on the white paper while your partner looks away. The disks represent the peppered moths. If you
are a “predator,” use the magnet wand to pick up as many disks as possible in 60 seconds while your
partner keeps time. The magnet wand represent the bird’s beak.
3. Count the number of each type of disk picked up in 60 seconds. Record these numbers below:
Total # of DIsks
Scattered
Trial
Background
Black
White
1
White
20
20
2
Black Paper
20
20
3
White
20
20
4
Black paper
20
20
Total # of Disks Picked
Up
White Disks
Black Disks
How does the number of each type of disks captured from the white paper compare with the number of each
type of disk remaining on the white paper?
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4. Replace the white paper with a sheet of black paper. If you are the time keeper, place the white and
black disks on the white paper while your partner looks away. The disks represent the peppered moths.
If you are a “predator,” use the magnet wand to pick up as many disks as possible in 60 seconds while
your partner keeps time. Again, record the data in the table above.
This time, how does the number of each type of disks captured from the black paper compare with the number
of each type of disk remaining on the paper?
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5. Change roles and repeat steps 2-4.
Part 2 - Analyzing Predator-Prey
Relationships
6. Examine the table at right, which represents data
from a 10-year study of a population of peppered
moths. The numbers represent moths captured in
traps that were located in the same area each
year.
7. Using the grid below and the data in the table above, construct a graph comparing the number of each
color of peppered moth captured. Plot the years of the study on x-axis and the number of moths
captured on the y-axis. Use a different color pencil to differentiate the two colors of moths captured.
Number of Light and Dark Moths Captured
# of Moths Captured
Years
Analysis
8. Using the graph made in Step 7, describe what happened to the moth population over time?
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9. Is color an important factor in capturing prey? Why?
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10. What is the relationship between the environment and the color of the peppered moth?
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11. Explain why an increase in the number of dark colored peppered moths occurred during the Industrial
Revolution.
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