Starburst® Evolution Lab
Purpose: to illustrate how populations can change in response to natural selection and other
evolutionary mechanisms.
Background: You have been the unwitting predators in an experimental model of how natural
selection affects populations. Evolution, at its most basic level, can be defined as any change in
the frequency of alleles in a population of organisms from generation to generation. During the
past several days, your benevolent teacher has been offering you a piece of Starburst® candy at
the beginning of class. This was an experiment to see if students (predators) had a preference for
certain flavors/colors of Starbursts®, and whether such preferences could influence the relative
frequencies of the flavors over time.
The initial population consisted of equal frequencies of four flavors: 25% cherry, 25%
strawberry, 25% orange and 25% lemon. Following each class, the survivors of each day’s
feasting (by YOU, the predators) reproduced, each spawning one offspring of the same color
(example: if there were 8 orange survivors at the end of class, then there would be 16 orange at
the beginning of the next class). Thus, color/flavor was passed from parent to offspring.
Instructions: You are being provided with the raw data from the different classes participating
in this experiment. Each column of data shows the numbers of each flavor BEFORE being eaten
by ravenous sophomores on that day.
1. Convert the raw data from your class only into percentages by dividing each flavor
amount by the sum of all flavors on that day and multiplying by 100. Copy the chart
below and record your percentages onto the chart.
Example (from Monday): 12 red/48 total = 0.25 x 100 = 25%
Change in Starburst Flavor Population Percentage Over Time
Monday
Tuesday
Wednesday
Thursday
Friday
Cherry (red)
Strawberry (pink)
Orange (orange)
Lemon (yellow)
2. Make a line graph of the percentage data for each flavor from your class only in the lab
section of your science notebook (use different colors to represent the different flavors).
Be sure to label your axes and title your graph!
3. Answer the questions below IQIA in your science notebook (lab section) (use scientific
definitions of terms).
Questions:
1. Describe the variability in the initial population of Starbursts® (what colors/flavors were
present in the beginning of the week?). In our simulation, is this variability heritable?
Hint: look up the definition and re-read background to answer this.
2. Describe, in words, what you observe about the relative frequencies (% of total
population) of each of the Starburst® flavors in your class over time.
3. According to your class’ data, rank the popularity of each of the Starburst® flavors:
Most Popular:
Second:
Third:
Least Popular:
4. How does your class’ data compare with results from the other classes? Provide a
possible explanation to account for any differences. (Hint: there are differences)
5. What is an adaptation (evolutionary definition)?
6. Which trait(s) could you conclude to be an adaptation for Starbursts® in your class?
Explain.
7. Can the adaptation(s) from your answer to question #6 be considered an adaptation in all
of the other classes as well? Explain your answer. Hint: Look at that period with
different data again.
8. Has evolution by natural selection occurred in our simulation? Why or why not?
9. What would you expect would happen over time if a pink starburst mutated on Monday
to have a yellow wrapper?
10. Given the exact same experimental parameters (your teacher doubling Starbursts by
color, etc..), describe in detail how you could have simulated artificial selection (page
379) assuming that you knew what was going on at the start of the week. In other words,
how could you have selected for the trait(s) that you wanted.