Modeling a Predator Prey Relationship

Objective:Students will learn how to simulate how nature keeps it's balance by manipulating an applet that models how wolves and rabbits would behave in the wild.

Materials: Each student will need

• A computer with internet access

Directions

Start a discussion with students about how you would model a habitat with grass, rabbits, and wolves. Ask some questions:

• What happens to the rabbits if they run out of grass?
• What happens to the wolves in the rabbits run out of grass?
• Do rabbits and wolves eat the same amount? Do they grow at the same rate? How quickly do they reproduce?
• How long do rabbits and wolves live? Do they both die around the same age?
• What happens if there are more bunnies than wolves? Would the bunnies take over and live forever?
• What would happen if there were lots more wolves than there are bunnies? Would the wolves live forever?

Have students open Rabbits and Wolves in their browsers.

Show the students how to change the metabolisms, maximum age, etc. of the rabbits and wolves by clicking on the "View/Modify Parameters" buttom below the simulation.

Have each student pick one or two parameters to change. After they change the parameter(s), have them run the model to see what changes happen.

Show students click the "View Population Graph" button. As they change different parameters and run the model, have them watch the population graph and see how the parameters affect the populations of the grass, rabbits, and wolves.

• When you increase the reproduction rate of the rabbits, how does that affect the rabbit population? What about the wolf population?
• What happens if you increase the initial number of rabbits? What about the initial number of wolves? You can find these in the View/Modify Startup Parameters.
• Try increasing and decreasing the maximum wolf age. What happens?

Give the students a challenge. Ask them to see who can make both the rabbits and wolves stay alive the longest by changing parameters. This works best if you change only one or two parameters at a time. If a student changes their parameters so much that they cannot keep their animals alive at all, have them refresh their browser window to reset the parameters.