I modeled the evolutionary process of gene flow by showing a certain population of Chads that get separated because of an earthquake. There is gene flow out of the population. I chose to represent my evolutionary process with a diagram because I thought a visual diagram would make it easier to understand what happens. The "pre-evolution" model shows two different colored Chads living in the same area and reproducing with one another. One is yellow and the other is green. Their offspring are yellow and green. The portion of the land that contained most of the yellow Chads breaks off and seperates into it's own island. This creates a geographic barrier that prevents the Chads from reproducing.The green Chads begin to reproduce with each other more often and eventually the yellow colored gene flows out of the population. This mode of evolution is not selective, it is random. The effect on the population is that over time the yellow gene color is lost on the original island. The source of the variation that leads to this mode of evolution is the gene flow of the yellow colored gene out of the population due to a geographic barrier change.