Download Sex and the Single Guppy

Sex and the Single Guppy
The purpose of this activity is to analyze
how guppy populations change over time.
The simulation activity allows you to start
with a pool of guppies and your choice of
predators, you will be able to watch what
happens to your guppy population and
how the introduction of predators can
affect the guppy's appearance. The
simulation will help you understand what
pressures drive guppy evolution.
*Activity adapted from PBS http://www.pbs.org
Introduction
First of all, familiarize yourself with the site. You should know each of the
following before proceeding to the simulation.





View the guppy gallery, know the color variations found among guppies
View the predator gallery, know the types of predators of guppies
Read about John Endler's experiment
View the three types of pools and know what guppy colors are common in
each area
Read the three possible hypotheses for guppy coloration
Experiment
Sexual selection and predation both play roles in the evolution of guppies. Both
can affect the coloration of male guppies. In this experiment, you will attempt to
answer the following question:
QUESTION: To what degree do predation and sexual selection affect guppy
coloration? (Which has a greater effect, or do they work equally to influence
guppy populations?)
Open the Guppy Sex Simulator!!!
http://www.pbs.org/wgbh/evolution/sex/guppy/ed_pop.html
Introduction:
1. If being flashy and colorful attracts predators, why do you think guppies
are so colorful?
2. View the guppy’s habitats, what habitat conditions would affect the
predator populations?
Endler’s Discovery and Variations of Guppy’s in Pools
3. Who is John Endler? What did he study and where did he study it?
4. For each of the three stream areas, describe the guppy coloration:
Pool 1:
Pool 2:
Pool 3:
5. Develop your own hypothesis about guppy coloration. The hypothesis
should answer the questions: Why do guppies in different areas of the
stream have difference in coloration? (You can choose from the list on the
simulation, or make up your own)
Guppy Simulation
In this part of the project, you will run 3 experiments and collect data about guppy
populations. This data will then be analyzed to determine whether your
hypothesis was correct or not. Make sure each simulation runs through at least 5
generations.
Trial 1
Guppy Color Types ___________________________________
Predator Species and Numbers _________________________
Results and Analysis:
Percentage of Brightest Guppies after 5 generations ______
Percentage of Bright Guppies after 5 generations ________
Percentage of Drab Guppies after 5 generations _________
Percentage of Drabbest Guppies after 5 generations ________
Analysis of the data: (What happened in this simulation, did the guppy coloration
change over time? Did the predators seem to affect guppy Coloration? )
Trial 2
Guppy Color Types ___________________________________
Predator Species and Numbers _________________________
Results and Analysis:
Percentage of Brightest Guppies after 5 generations ______
Percentage of Bright Guppies after 5 generations ________
Percentage of Drab Guppies after 5 generations _________
Percentage of Drabbest Guppies after 5 generations ________
Analysis of the data: (What happened in this simulation, did the guppy coloration
change over time? Did the predators seem to affect guppy Coloration? )
Trial 3
Guppy Color Types ___________________________________
Predator Species and Numbers _________________________
Results and Analysis:
Percentage of Brightest Guppies after 5 generations ______
Percentage of Bright Guppies after 5 generations ________
Percentage of Drab Guppies after 5 generations _________
Percentage of Drabbest Guppies after 5 generations ________
Analysis of the data: (What happened in this simulation, did the guppy coloration
change over time? Did the predators seem to affect guppy Coloration? )
Summary
1. Describe how predators influence guppy coloration.
2. Was your hypothesis correct, use your data to justify your answer.
3. What does it mean that “male guppies live in a crossfire between their
enemies and their would be mates”?
4. Why do you think guppies in different areas of the stream have different
coloration?
5. How does the number of predators affect the number of brightly colored
guppies?
More about Sexual Selection - extra credit if you have the time to read this
article.
Read the article in Scientific American titled: “How Females Choose Their Mates”
http://www.sciam.com/1998/0498issue/0498dugatkin.html
After reading the article, summarize an example of female mate choice. Describe
how the female of the species chooses a mate, and explain some possible
reasons or benefits she gains from that particular choice.
Suggest three reasons for females choosing a flashy or conspicuous mate.
How does social pressure affect the mating behavior of guppies? (Hint: click on
guppy behavior picture)