Name:
Date:
Period:
Objectives:
1. Describe the importance of coloration in avoiding predation.
2. Relate environmental change to changes in organisms.
3. Explain how natural selection causes populations to change.
Materials:
Sheet of white paper
Sheet of newspaper
Forceps
Colored Pencils
Clock with Second Hand
30 newspaper circles (made with hole punch)
30 white circles (made with hole punch)
Purpose: In this lab, you will simulate how predators locate prey in different
environments. You will analyze how color affects an organism's ability to survive in
certain environments.
Background Information:
Industrial Melanism is a term used to describe the adaptation of a population in
response to pollution. One example of rapid industrial melanism occurred in populations
of peppered moths in the area of Manchester, England from 1845 to 1890. The
peppered moth is fairly common in England. It can be found in two forms – the dark
form and the light form.
Before the industrial revolution, the trunks of the 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 dark spots. Prior to 1850, insect collectors had never
collected a dark form of this moth. As the industrial revolution progressed, the tree
trunks became covered with soot and turned dark. In 1850, a dark form was collected
near the factory city of Manchester. Over a period of 45 years, the dark variety of the
peppered moth became more common.
In fact, near many industrial cities in England the dark form accounted for about 95
percent of the peppered moth population. Away from industrial centers the moth was
usually found in the light form. In non-industrial areas, tree trunks were usually found in
their lighter, natural color. Both forms of the moth are preyed upon by birds when the
moths rest on the trunks of trees. Among the peppered moth population, the genes for
both the light form and the dark form have long existed. However, before 1850, the
dark form appeared only rarely. The increased number of dark moths is a matter of
natural selection.
1
Procedure:
1. Place a sheet of white paper on the table.
2. Have one person spread 30 white circles and 30 newspaper circles over the surface
while the other person isn't looking. The collecting cup should not be placed directly
next to the sheet.
3. The "predator" will then use forceps to pick up as many of the circles as s/he can in
15 seconds. Record the number of white and newspaper circles collected.
4. Replace the dots in the cup and repeat this experiment two more times.
5. Determine the average number of both white and newspaper circles collected on the
white background.
6. Replace the white background with a newspaper background.
7. Repeat steps 2 through 5 with the newspaper background.
Data Table
Starting Population
Trial
Background
Newspaper
White
1
white
30
30
2
white
30
30
3
white
30
30
Average
white
1
newspaper
30
30
2
newspaper
30
30
3
newspaper
30
30
Average
newspaper
Number Picked up
White
Newspaper
White
Newspaper
Analysis:
1. What did the white circles and the newspaper circles represent?
2. What did the white background and the newspaper background represent?
2
3. What did the experiment show about how prey are selected by predators?
4. What moth coloration is the best adaptation for a dark (newspaper) background?
How do you know? Use the data to support your answer.
5. What would you expect the next generation of moths to look like after trial 3 using
the newspaper background? Explain your reasoning.
6. How does the simulation model natural selection?
8. Draw a picture of the least desirable
color adaptation of a peppered moth
on a light tree trunk.
7. Draw a picture of the best survival
adaptation of a peppered moth on
a dark tree trunk.
3
9. Examine the table and construct a graph. Plot the years of the study on the X-axis,
and the number of moths captured on the Y axis. You should have 2 lines on your
graph - one for light moths, and one for dark moths.
10. Explain in your own words what the graph shows.
11. Describe a situation where this type of selection might occur.
4
Year
# of Light
Moths
Captured
# of Dark
Moths
Captured
2
537
112
3
484
198
4
392
210
5
246
281
6
225
337
7
193
412
8
147
503
9
84
550
10
56
599