Fitness & Natural Selection
Activity 1: Wooly Boogers Eatin’ Beans
Background: Four hundred years ago, on a distant planet, there were three types of a creature called Wooly
Boogers. Each type of Wooly Booger was similar except for their mouths. All of the Wooly Boogers ate beans, but
they ate in different ways. Some Wooly Boogers had a “binder clip” mouth, some had a “tweezer” mouth, and
some had a “knife” mouth.
 What are some things that will happen as the Wooly Booger populations continues to increase over time,
continuing to eat the same food?
One year, a new type of Wooly Booger was discovered on the planet! This Wooly Booger had a “spoon” mouth.
This type was rare at the time—only two were discovered on the planet.
 How do you think a Wooly Booger with a “spoon” mouth came to be? In other words, how did it get a
“spoon” mouth?
 Which inherited variations of Wooly Booger mouths will help them survive on this distant planet?
Hypothesis: If food becomes scarce on this planet, then _____________________________________
______________________________________________________because________________________________
________________________.
The whole class will participate, taking on the role of a different Wooly Booger. Available supplies: spoons, binder
clips, tweezers, knives, beans, stopwatch.
 How can we test your hypothesis? Brainstorm some ideas!
Procedure: Each member of the class will be one of the Wooly Boogers. Only two will have spoon “mouths”, and
the rest of the class will be divided among the remaining 3 “mouths.”
You Wooly Boogers will run through several rounds of eating with your assigned mouth. You must gain at least 20
beans in each round to survive. Don’t forget to use your “mouth” the way you would as a Wooly Booger.
The first round will be 1 minute long, the second round 45 seconds, then 30 seconds. If you do not collect 20
beans in the round, you “die.” Don’t worry! You will become an offspring of one of the “survivors” (Wooly
Boogers with “mouth” that enabled them to get 20 beans). After each round, we will collect data and record it in
the table.
Data:
Tweezer
Year 1
Year 2
Year 3
Year 4
Year 5
Year 6
Knife
Clip
Spoons
Initial:
Initial:
Initial:
Initial:
Final:
Final:
Final:
Final:
Initial:
Initial:
Initial:
Initial:
Final:
Final:
Final:
Final:
Initial:
Initial:
Initial:
Initial:
Final:
Final:
Final:
Final:
Initial:
Initial:
Initial:
Initial:
Final:
Final:
Final:
Final:
Initial:
Initial:
Initial:
Initial:
Final:
Final:
Final:
Final:
Initial:
Initial:
Initial:
Initial:
Graph: Create a graph of the survival of each type of Wooly Booger over time. Use your Initial Values.
Conclusion: Look back at your hypothesis and write a conclusion in CER format to support or reject your
hypothesis.
C:
E:
R:
Questions:
1) What if a population of Wooly Boogers settled on another planet with a different food source? (Hard
seeds or nectar from flowers) Do you think that the results would be different? Explain.
2) What happens to animals that cannot compete as well with other animals in the wild?
3) When biologists talk about fitness, they specifically mean the ability to survive and reproduce. According
to this definition, which type of Wooly Booger would biologists consider fittest?
4) How did the “spoon” mouth Wooly Booger get its spoon mouth?
5) As we determine a species’ fitness, is natural selection occurring? Defend your answer with evidence from
the activity.
Activity 2: Pocket Mouse
https://www.youtube.com/watch?v=AMtT5_AQmLg
Watch the video clip on the Pocket Mouse. Take notes on the most important ideas here:
1) Explain why a rock pocket mouse’s color influences its overall fitness. Remember that “fitness” is defined by
an organism’s ability to survive and produce offspring.
2) Why did dark-colored rock pocket mice first appear in a population of light-colored rock pocket mice?
3) Why do dark-colored rock pocket mice on dark lava flows have white bellies?
4) In your own words, define mutation.
5) Nachman examined dark-colored mice from two different populations living hundreds of miles apart. The
mice looked nearly identical. Their dark color was caused by two different genes. What does this tell you?
6) Near the end of the film, Dr. Sean B. Carroll states that “while mutation is random, natural selection is not.” In
your own words, explain how this is possible/what it means.