Natural Selection is a great science simulation tool. It is made by the PheT department at University of Colorado. Written in Java, this simulation can be run on Mac OS X, Windows, Linux and even Java-capable web browsers. It deals with Natural Selection. Natural Selection, a theory by Charles Darwin, establishes that species will evolve to overcome certain difficulties or challenges in their environment. This simulation uses rabbits to illustrate the theory.
The environment of the simulation is a brown plain with some trees and a blue sky. The simulation starts with one rabbit and no selection factor. You can add a second rabbit, which will mate with the other rabbit and start the growth of the rabbit population. You can then add mutations to the rabbits. The available ones are brown fur, long tail and long teeth. When the colony starts growing you will see that the white rabbits increase in numbers quite a lot, while the brown ones don't grow so much. This changes when you add a selection factor, like wolves. When wolves are added, they will go for white rabbits primarily because they are easier to spot. The brown rabbits camouflage with the background. The wolves are still going to eat some of the brown rabbits, though. But when you add the wolves as a selection factor and the mutation selected is brown fur, you will notice that the white rabbits will be the secondary species, if you will. And the wolves will almost always eat them all. The other selection factor is food. You can also change the environment to the arctic, which will change the results of the simulation.
At the bottom of the screen there is a graph that shows the total population size and the population size of each mutated rabbit type.