Evolution squirrels. The presence of Chattahoochee riverEvolution squirrels. The presence of Chattahoochee river

Evolution is affected by several factors: natural selection, genetic drift, genetic flow, mutation and sexual recombination. Natural selection is the most basic factor that leads to evolution, since environment is the fundamental resource for organisms to survive. Adaptation is one cause for natural selections. It is considered as any changes in organisms due to the situation of environment to have stable reproduction and better living skills in the environment. For example, during the industrial revolution period, due to the over burned coal, many trees are covered by black coal powder and were seriously polluted. Moth then turned into darker color for better camouflage. However, after pollution is controlled later on, the trees gradually came back to their natural color. The frequency of light moth increased a lot. The color changes of moth act as adaptation to fit in environment better, which is considered as natural selection process. In order to observe the adaptation happens in squirrels, two foods for squirrels are selected. Wheat will be only planted on one side of Chattahoochee river, while the other side only supply acorns for squirrels. The presence of Chattahoochee river plays a role of barrier to prevent squirrels traveling back and forth so that each side of river forms a new environment with specific food resources. The comparison between wheat and acorns shows the difference that wheat has smaller fruits inside and is easier to peel off; yet, acorns have bigger fruits inside harder shells, which is harder to peel off. On the side of wheat supply, squirrels are expected to form smaller but sharp teeth in order to fit in the shape and size of wheat as their food. Since wheat is easy to peel off and tiny, squirrels do not need to stretch their jaw to eat it. As a result, their jaw structure will be smaller than before. On the other side of river with only acorns as food, squirrels are expected to have stronger jaw structure due to the bigger size of acornsand their hard shells. Since the acorns shell is hard to break, the teeth of squirrels tend to grow bi