Saint Mary’s University
School of Health and Natural Sciences
CENTER FOR NATURAL SCIENCES
Bayombong, Nueva Vizcaya
WORKSHEET/ SIMULATION 5
How Can Evolution be Modeled? (Peppered Moth Simulation)
Introduction:
Evolution is said to be the central theme of biology. Most concepts learned
throughout biology are rooted in the concept of evolution. Evolution is considered as the
gradual change of organisms over time. In this worksheet, modern organisms have
descended from ancient organism. Modern organisms keep replacing ancient
organisms to fill the niches they left.
According to Charles Darwin, species evolve by means of natural selection. This
results in the changes in the inherited characteristic of a population. These traits
increases the fitness of the species in the environment over time.
Objectives:
1. Describe
the
importance
of
coloration
in
avoiding
2.
Relate
environmental
change
to
changes
in
3. Explain how natural selection causes populations to change.
predation.
organisms.
Materials:
Sheet of white paper and newspaper
Forceps
Clock with Second Hand
30 newspaper circles 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 and organism's ability to survive in certain environments.
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. 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. As the industrial revolution progressed, the tree
trunks became covered with soot and turned dark. Over a period of 45 years, the dark
variety of the peppered moth became more common.
Procedure.
1. Place a sheet of white paper on the table and have one person spread 30 white
circles and 30 newspaper circles over the surface while the other person is not looking.
2. The "predator" will then use forceps to pick up as many of the circles as he can in 15
seconds.
(
assign
a
predator,
could
be
your
sibling
)
3. The number that are left are doubled to represent the next generation
4. This trial will be repeated with white circles on a newspaper background, newspaper
circles on a white background, and newspaper circles on a newspaper background.
Record the data in chart below.
Populations Start on White Background
Starting Population
Final Populations (How many of the original were
left)
Generation
Newspaper White
Newspaper
White
1
30
30
24
24
2
48
48
42
44
3
84
88
73
81
4
146
162
130
158
5
260
316
244
314
Double
these
final
numbers to get your
starting population for the
next generation
Populations Start on Newspaper Background
Starting Population
Final Populations (How many of the original were
left)
Generation
Newspaper White
Newspaper
White
1
30
30
25
19
2
50
38
46
20
3
92
40
85
25
Double
these
final
numbers to get your
starting population for the
next generation
4
170
50
165
35
5
330
70
324
68
Analysis
1. Describe how the population of moths changed in each generation for both the
newspaper and the white moths.
For the white background, the white circle paper (white moths) adapted well to its
white background compared to the newspaper circle paper (dark moths). As the
generation increases, so does the number of white-colored moths. This means that the
white moths population had increase over the time.
The dark moths on the other hand, cannot adapt well to the white background.
This made them very visible, hence allow them to be seen by the “predator” clearly. Its
population slightly decreases over the following generations.
2. What moth coloration is the best adaptation for a dark (newspaper) background?
How do you know?
The dark moths (newspaper) are well suited to the dark (newspaper) background.
Since the dark moths shared the same color of the the dark (newspaper) background, it
is not that visible compared to the other one. Like a camouflage, the dark moths
blended well with their environment.
3. How does this activity on simulation model natural selection?
This activity relates natural selection in the way it can portray the changes
accumulated by a certain population over time. Evolution in the means of natural
selection states that, the environment or condition dictates what traits will improve the
survival and reproductive success of the population. Like in the activity, the white and
newspaper backgrounds become the “environment” or the “condition” the moths live in.
The population of the moths lie at the certain environment or the certain condition they
are in. Both the population of the dark and white moths increases according to the
background they are in.
Since the white moths adapted well to the white background, it increased its
survival and reproductive rate. Compared to the dark moths that live into the same
background, its survival and reproductive rate depleted.
4. 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.
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
Legend: Red is for Light Moths
Yellow is for Dark Moths
X-axis represents the years and Y-axis represent the numbers of moths.
0
700
650
600
550
500
450
400
350
300
250
200
150
100
50
0
1
2
3
4
5
6
7
8
9
10
5. Explain in your own words what the graph shows. What type of environment do you
think these moths live in?
The graph shows the generation of both light and dark moths and their
population. There are two figures, the red line which represents the light moths and the
yellow line, which represents the dark moths.
As their generation goes by, the light moths population started going down. The
dark moths however, started from a small population, and is continuing to grow. It
appears that the condition or the environment that both moths live in is only favorable to
the dark moths. This gives the dark moths an advantage to reproduce and multiply
rapidly. Unlike the light moths, the condition or the environment they are currently in is
not appropriate for them. This results to a decrease into their population over time.
The type of environment both moths live in is mostly favorable to the dark moths.
Hence, it could be a forest were dark trunk trees grow.
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