Natural Selection Computer Simulation
Download the simulation from: http://phet.colorado.edu/en/simulation/natural-selection
Before you begin:
1. What is natural selection?
2. What is a genetic mutation?
3. What selection factors other than wolves and food availability might affect the rabbit population?
Design Your Experiment
In this exercise you will control the mutations and the environment of a population of rabbits. You will create four situations and design an experiment to test each one. Your hypothesis (what you think will happen) will follow the format where you fill in the (…) with your own ideas and reasons.
I think that (select a rabbit trait) rabbits will be (more/ less) likely to survive under (type of selective factor) within the (type of environment) environment, because….. (explain how their trait will help them to survive or not)
***You must make at least one hypothesis for each of the three different mutations***
To run the experiments follow these steps:
1. For each of the experiments, begin by adding a friend and a mutation. Wait until the rabbits have reproduced 3 times to make sure there are enough rabbits. This is called the F3 generation. You can see a jump up in the graph every time the rabbits reproduce a new generation.
2. Add the selective factor. After adding the selective factor let the simulation run for another 3 or 4 generations.
3. Use the population numbers from the graph to get the numbers for your table.
4. What do your results show? Was your hypothesis correct?
5. Repeat for experiments 2, 3 and 4.
For each experiment there will be a control population (no mutation) and an experiment population (mutation). Fill in the following chart using results from the graph:
Experiment
and
Hypothesis Trait (color or teeth or tail) Selective Factor
(food or wolves) CONTROL
population after 3 generations (F3) CONTROL
Final Population EXPERIMENT
Initial Population at F3 EXPERIMENT
Final Population Conclusion/
Observation
I think that brown rabbits will be more likely to survive under wolf predation within the equator environment because they blend in to the environment and are difficult for wolves to see color Wolves 35 white rabbits 0 white rabbits 15 brown rabbits 120 brown rabbits Brown rabbit population increased and white rabbit population decreased so hypothesis is correct
Questions
1. Based upon your experiments using this simulation model, what conclusions are you able to make about each of the three different types of traits in rabbits?
2. What happens to animals that cannot compete as well with other animals in the wild?
3. Sometimes animals that are introduced into a new area out-compete and endanger resident species, why do you think this happens?
4. If only one type is considered the “fittest” in an environment, why do we still have so much variation among species? For example: Why do some birds have very long pointy beaks, while other birds have short flat beaks?
5. How do you think diseases can affect natural selection?
6. How well does this simulation experiment show natural selection? How could it be improved?
