Describe the importance of coloration in avoiding predation
Relate environmental change to changes in organisms
Explain how natural selection causes populations to change
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. You will use brown and white beans to simulate different colored
moths.
OBJECTIVES:
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 (Biston betularia) in the area
of Manchester, England from 1845 to 1890. Before the industrial revolution, the trunks of the trees in the
forest around Manchester were light grayish in color due to the presence of lichens (a type of fungus) on their
trunks. Most of the peppered moths in the area were light colored with dark spots. As the industrial revolution
progressed, the tree trunks became covered with soot which killed the lichens on the trees and revealed the
dark bark of the trees. Two variations of the peppered moth (light and dark) resided on these trees. Over a
period of 45 years, the dark variety of the peppered moth became more common.
PROCEDURE:
1. Write down a few brief notes on the important points about industrial melanism.
2. Neatly cut out and glue down the white data table into your notebook after the notes. Do not write on
the blue lab sheets. White data tables can be found on your lab tray.
3. Place a sheet of white paper on the table and have one person spread 30 white “moths” and 30 brown
“moths” over the surface while the other person (the predator) is NOT LOOKING!
4. The "predator" will then use forceps to pick up as many of the “moths” as he/she can in 20 seconds.
The non-predator person should time this with the stopwatch.
5. Switch roles, repeat the predation activity and average the data for both predators.
6. See your data table to figure out what to do next in order to set up for the next two environments.
7. Review steps 2 – 5 for both brown and green backgrounds.
ANALYSIS: Write the following questions and answer them
# of Light
# of Dark
(YOU DO NOT HAVE TO WRITE OUT QUESTION #7,
Colored Moths
Colored Moths
JUST GLUE DOWN THE GRAPH.)
Year
Captured by
Captured by
1. What did the experiment show about how prey are
Predators
Predators
selected by predators?
1
700
98
2. What moth coloration is the best adaptation for a dark
2
537
112
(brown) background? How do you know?
3. The next generation of moth offspring in the white
3
484
198
environment would be expected to be predominantly what
4
392
210
color?
4. The next generation of moth offspring in the brown
5
246
281
environment would be expected to be predominantly what
6
225
337
color?
7
193
412
5. Which environment produced easy predation for both
variations of moths? Why?
8
147
503
6. How does the simulation model natural selection?
9
84
550
7. Examine the table TO THE RIGHT and NEATLY
10
56
599
construct a double line 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).
REMINDERS: title, neatness, key, even spacing and consistent intervals. Glue this graph in your
notebook and answer the next two questions. Graph paper can be found on the bookshelf by the door.
8. According to your graph, which variety of moth increased over the 10 year period?
9. Describe a situation where this type of selection might occur.
STARTING MOTH
POPULATION
Predator BACKGROUND
Brown Spotted
White
1
white
30
30
2
white
30
30
NUMBER OF MOTHS
CAPTURED
White
Brown
Average for white background
1
brown
30
30
2
brown
30
30
Average for brown background
1
green
30
30
2
green
30
30
Average for green background
STARTING MOTH
POPULATION
Predator BACKGROUND
Brown Spotted
White
1
white
30
30
2
white
30
30
Average for white background
1
brown
30
30
2
brown
30
30
Average for brown background
1
green
30
30
2
green
30
30
Average for green background
NUMBER OF MOTHS
CAPTURED
White
Brown