Name___________________________________________________ Date_________________________Period____
PHET Simulation Natural Selection on Bunnies
Purpose: To test how potential selective pressures affect the gene frequency for different traits in bunnies.
Gene frequency means how common different genes (alleles) are in the population.
Selective pressures are factors that affect the survival of organisms in a population (such as predators, parasites, lack of
adequate food, and climate conditions) in a way that disproportionately affects portions of the population based on
their traits.
Go to the website: https://phet.colorado.edu/sims/html/natural-selection/latest/natural-selection_en.html
 Open the lab.
 Decide if you want a desert or arctic environment (sun or snow icon).
 Select add a mate.
 Add dominant mutations for all 3 traits. (fur color, ears and teeth). Dominant alleles (gene forms) are shown if
individuals have one copy, unlike recessive where one copy of the allele can be hidden.
 After one generation, the mutation will occur in one individual (17% of that initial population).
 Select proportion so that you are seeing the percentage with each trait.
 Observe what would happen to the bunny population if no selective pressure existed (no limits on food, no
predators)
 You can speed up the timeline of generations by clicking the fast forward arrows.
Environment type _______________________________________
No Selective Pressure
1. How many generations until the bunnies took over the world if no selective pressure was present? _________
Generation
1
Final Generation
% with Brown Fur
17%
% with Floppy Ears
17%
% with Long Teeth
17%
 Set up trial runs to test each of the possible selective pressures (wolves, tough food, limited food) one at at time.
 Observe the change proportions of the traits over 10 generations and fill in the charts below.
Selective Pressure: Wolves
Generation
1
10
% with Brown Fur
17%
% with Floppy Ears
17%
% with Long Teeth
17%
Determine whether the wolves were a selective pressure that acted against or in favor of each trait. Or did the wolves not
act as a selective pressure on the trait .
2. In the __________________ environment, wolves were a selective pressure (Fill in: against, in favor or no selective
pressure.)
A. _______________________ for brown fur. Evidence _____________________________________
B. _______________________ for floppy ears. Evidence _____________________________________
C. _______________________ for sharp teeth. Evidence _____________________________________
3.
Predict how the selective pressure of wolves would compare if you had chosen the alternate environment. Explain
your answer.
Selective Pressure: Tough Food
Generation
% with Brown Fur
1
17%
10
% with Floppy Ears
17%
% with Long Teeth
17%
Determine whether the tough food was a selective pressure that acted against or in favor of each trait. Or did the tough
food did not act as a selective pressure on the trait.
4. In the __________________ environment, tough food was a selective pressure (Fill in: against, in favor or no
selective pressure.)
A. _______________________ for brown fur. Evidence _____________________________________
B.________________________ for floppy ears. Evidence _____________________________________
C. ________________________ for sharp teeth. Evidence _____________________________________
5. Explain how the process of natural selection worked for one of the selective pressures on one of the traits.
6.
Explain how the virtual lab illustrated the need for the three prerequisites for natural selection: differential
reproduction, variation and heritability. (Differential reproduction is differences in which organisms are
surviving to be able to reproduce- the struggle for survival).
Differential reproduction (Hint: look at the results of the gene frequency when you did not add a selective
pressure.):
Variability:
Heritability: