This model is an example of genetic drift. In it, patches randomly exchange colors with their neighbors. After enough turns, a color will gain a slight dominance; by statistical advantage, a dominant color becomes more likely to win the entire grid. However, because the process is random, there will usually be many dominant colors before one color finally wins. It shows how trait drifts can occur without any particular purpose or 'selection pressure'.
For detailed instructions on using the program, take a look at the info window from the Local Patches model.
Click on one of the pictures to see a quicktime movie of the model: