CHAPTER INVESTIGATION
Modeling Natural Selection
OVERVIEW AND PURPOSE Organisms that are best
adapted to their environment tend to survive and reproduce.
In this lab you will
• play a game that models the effect of natural selection in
an environment
• determine what happens to a group of organisms as a
result of natural selection
Write
Question
It Up
As you read the steps to the game, think about what makes a
population successful in an environment. How will the game
model natural selection?
MATERIALS
• pair of number cubes
• 16 red paper clips
• 16 blue paper clips
• 16 yellow paper clips
Procedure
Make a game board like the one shown below. In your
Science Notebook make a table like the one on page 507
to record your data.
1
2
3
4
1
2
3
4
Count out 10 red paper clips,
4 blue paper clips, and 2 yellow
paper clips. Randomly place the
paper clips on the board. Keep
the rest of the paper clips in a
reserve pile.
506 Unit 4: Life Over Time
Each color represents a different population of
a single species. The board represents the environment. Roll the number cubes to determine
which paper clips “live,” or remain on the board,
and which paper clips “die,” or are removed
from the board. Predict which color paper clip
you think will be the last remaining color. Write
down your prediction.
Roll the number cubes to determine which
square, or part of the environment, will be
affected. For example, 2,3 indicates the paper
clip in column 2, row 3. If the numbers 5 or 6
come up, roll again until you have a number
between 1 and 4 for each cube.
Now roll one cube to see what will happen to
the paper clip or organism in that square. Use
the chart below to determine if the paper clip
“lives” or “dies.” If the paper clip lives, repeat
steps 4 and 5 until one paper clip dies, or is
removed from the board. In your table, record
which colors live and die.
Observe and Analyze
Write
It Up
1. OBSERVE Which color paper clip filled the
board at the end of the game?
2. PREDICT Compare the results with your
prediction. Do the results support your
prediction?
Conclude
Write
It Up
1. INFER What does the random selection by
rolling both number cubes represent? Explain.
2. INFER If the individual paper clips represent
different members of a single species, then
what might the different colors represent?
3. LIMITATIONS What problems or sources
of error exist in this model? Give examples.
4. APPLY How does this game model
natural selection?
Red
Remove if you roll a
1, 2, 3, 4, or 5.
INVESTIGATE Further
Blue
Remove if you roll a
1, 2, or 3.
Yellow
Remove if you roll a
1 or 2.
CHALLENGE Occasionally mutations occur in
a population that can either help or damage the
population’s chance of survival. Add another step
to the game that would account for mutations.
Now that a paper clip has been removed, you
need to see what population will reproduce to fill
that space. Roll both cubes to choose another
square. The color of the paper clip in that square
represents the population that will “reproduce.”
Pick the same color paper clip from your reserve
pile and place it on the empty square. All squares
on the board should always have a paper clip.
al Selection
Modeling Natur
n
s in a Populatio
Table 1. Pattern
Die
Live
Paper Clip Color
Continue playing the game by repeating steps
4–6 until all the paper clips on the board are the
same color.
Chapter 14: The History of Life on Earth 507