Professor John Endler traveled to Trinidad in the 1970s to study wild guppies. The guppies live in small streams that flow down the mountains from pool to pool. In this activity, you will take part in an online simulation of Endler's work. You will collect data, formulate a hypothesis, and run a series of experiments. You will find out about the interplay between natural selection and sexual selection in this wild population of guppies.
1.
Go to http://www.pbs.org/wgbh/evolution/sex/guppy/
2.
Read the screen and answer the following question: Why is it necessary for the guppy to be camouflaged?
3.
Click on “CHECK OUT THE GUPPY GALLERY”. Look at several of the guppies and their predators. Make a mental note of the size of each one.
4.
Click on “back to simulation”. When ready click on “I’m ready to find out”. Read the information about Endler’s discovery. When finished click on “What causes guppy color variation?” Should you decide to take a look at the various guppy pools – you may not be able to get back to this page and have to start over from the beginning.
5.
Read the three hypotheses. If you can think of your own hypothesis, write it in the space below. If not, select the one you think seems most reasonable from the list and write it below.
6.
Click on “to start, choose how you want to set up your simulation pool”. Select what you prefer in guppy population. Be sure to select a population that will help you test. What did you choose? ______________
7.
Select what you prefer in predator population. What did you choose?
____________________________
8.
Click on “run simulation” and run it for between 5 and 10 generations. As soon as you do, jot down the following:
Initial Number of guppies: _____
When over 5 generations have been completed, click on “stop simulation”. Click on “view results”
Write down the initial population type of guppies:
The number and name of predators:
The number of generations:
The number of weeks:

Male color types and %:
Brightest male guppy
Bright male guppy
Drab male guppy
Drabbest male guppy
____%
____%
____%
____%
What was the analysis of your data?
9. Was your hypothesis supported by your data? If so, why? If not, you may want to select different populations and run the simulation again. Write down the initial population type of guppies:
The number and name of predators:
The number of generations:
The number of weeks:
Male color types and %:
Brightest male guppy
Bright male guppy
Drab male guppy
Drabbest male guppy
What was the analysis of your data?
____%
____%
____%
____%
10. Try other types of simulations of your choice. Summarize what you have learned form your experiments.
11. Upon completion of your last simulation, answer the following questions:
1.
Why do some guppies tend to be drabber than others?
2.
Why so some guppies tend to be more colorful?
3.
What role does color play in guppy survival?
4.
Explain the push and pull that the environment has on the coloration of guppies in Endler’s pools.