Honors Biology I
Peppered Moth Survey
Background:
Industrial melanism is the term used to describe the adaptation of darkening by
an organism in response to industrial pollution. One example of rapid industrial
melanism occured in the peppered moth, Biston betularia, in the area of Manchester,
England, from 1845 to 1890.
Before the Industrial Revolution, the trees in the forest around Manchester were
light grayish-green due to the presence of lichens on their trunks. Peppered moths,
which lived in the area, were mostly light-colored with dark spots. Very few moths were
dark colored with light spots. Their coloring served as a camouflage against predators,
especially birds. As the Industrial Revolution progressed, the trees became covered
with soot and the lichens died, which turned the tree trunks dark. Over a period of 45
years, a change took place in the peppered moth population in this area: light-colored
moth numbers decreased and dark-colored moth numbers increased.
In this investigation, you will simulate a predator-prey situation and determine if
color contrast has an effect on the ability of a predator to rapidly locate prey. In the
second part of the investigation, you will study the data on peppered moth coloration as
actually reported over the course of several years. You will then determine the
relationship between the environmental changes and the color variations of the
peppered moths by using the research data to graph the results of an environmental
adaptation.
Problem:
Materials:
What is the relationship between environmental changes and the color
variation of the peppered moth?
sheet of newspaper
sheet of white paper
graph paper
30 newspaper disks
30 white paper disks
forceps
Procedure:
Part A- Simulating Predator-Prey Relationships
1) You will use the disks of white paper and newspaper to simulate prey (peppered
moths). You will use forceps to simulate a bird’s beak and capture as many of
your prey as possible in a 15 second time period.
2) Place the white paper on your lab table. While your teammate is looking away,
scatter 30 white disks and 30 newspaper disks on the paper. When your partner
is ready, let them hunt with their forceps and you start timing.
3) When 15 seconds have elapsed, count how many of each type of disk were
picked up. Record the number of captured disks of each type and the number of
disks remaining for each type.
4) Replace the white paper with a sheet of newspaper. While your partner is
looking away, scatter 30 newspaper disks and 30 white disks. Repeat the
hunting procedure. Record the number of each type of disk picked up and the
number of each type that remains.
Name of Predator 1: _____________________________________
# picked up
# left
White on White
Newspaper on White
White on Newspaper
Newspaper on Newspaper
5) Change roles. You play the predator, while your partner sets up the disks.
Name of Predator 2: _____________________________________
# picked up
# left
White on White
Newspaper on White
White on Newspaper
Newspaper on Newspaper
Did you and your partner each pick up the same amount of “prey”? ___________
6) After you have recorded data for one trial using a white background, and one trial
using a newspaper background for each lab partner, compute the Percentage of
Available Prey Recovered for the contrasting and matching background
situations.
To do this, divide the total number of disks recovered that contrasted with
their background by the total number of disks of that type. Repeat this procedure
with the total number of disks recovered that matched their background.
Example: If you scatter 30 newspaper disks and 30 white disks on a
sheet of newspaper, and you recover 5 newspaper (matching) disks and 15 white
paper (contrasting) disks, your recovery rate is:
5 x 100% = 17% for the matching background
30
Likewise your recovery rate is:
15 x 100% = 50% for the contrasting (opposite) background
30
Percentage of Available Prey Recovered
Predator 1
Predator 2
White on White %
Newspaper on White %
White on Newspaper %
Newspaper on Newspaper %
Did the background play an important role in your selection of “prey”? Explain.
____________________________________________________________________
____________________________________________________________________
Part B- Graphing and Analyzing Predator-Prey Relationships
7) Table A represents data from a 9 year study of two varieties of the same species
of peppered moths. The numbers represent moths captured in traps for 9
consecutive years. The traps were located in the same are each year.
Table A.
Year
1
2
3
4
5
6
7
8
9
Light moths captured
537
484
392
246
225
193
147
84
56
Dark moths captured
112
198
210
281
357
412
503
594
638
8) Using the data provided in Table A, construct a line graph, on graph paper,
comparing the numbers of each variety of peppered moth. Label the axes with
the years of the study (x-axis) and the number of moths captured (y-axis). Use
different colored pencils to indicate the two color variations. Be sure to include a
key and title your graph.
Questions: Use your graph and this lab to answer the following questions.
1) What preys on the peppered moth?
2) If the bark of the trees is dark and the moths that rests there are light, what will
happen to the light-colored moths?
3) What could have caused the first dark-colored moth?
4) What caused the tree trunks of many trees in Manchester to turn from a light
color to a dark color?
5) Using your graph, what variety of moth population increased over the 9 year
period? Which moth variety decreased?
6) What is the name of this type of evolutionary change?
7) What could be done to return the environment of the peppered moth to its
original state?
8) What effect would cleaning up the environment have on the moths?