The theory of evolution was started up by Charles Darwin, the scientist who established that all living things come from one common ancestor. He introduced the theory that evolution results from the process natural selection.
Natural Selection
Natural selection is one of the forces that drives evolution. Organisms that are well adapted to their environment will generally survive long enough to pass on their genes to their offspring. Organisms that have genes that are harmful to them are unable to survive long enough to pass on genes. As a result, no offspring will be produced. The harmful genes/traits are unable to be passed on and will die off within that population/species.
The peppered moth is a common moth in Europe, Asia and North America. The moths has two appearances, the light, speckled morph and the dark morph. These two morphs help it camouflage from its biggest predator: the bird.
When the moths were light, they would rest on woodland lichens, camouflaging in the flowers and staying hidden form the birds that preyed upon it. When the industrial revolution came, soot killed the lichens and turned the trees black. The moths were no longer able to camouflage on the dark trees. They were killed and eaten. Over time, natural selection killed off the light genes, and dark moths replaced the lighter ones. In 1956, the Clean Air Act removed soot from the nation’s sky, and the trees began to turn light. Once again, the moths were exposed, and once again, they evolved to stay hidden.
As could be seen from the moths, the more favorable traits are passed on, while the harmful or less desirable traits are lost.
Darwin’s finches
Charles Darwin came up with the theory of evolution. He visited a series of islands to study organisms and how they lived. There, he noticed finches, a type of bird.
Darwin noticed that the birds from the different islands looked similar and were the same species (finches), but they weren’t exactly the same. A finch on one island had a deeper beak than a finch on the other island. Darwin wondered why that was and came up with the theory of evolution.
The finches from the different islands were perfectly suited to the resources of their island. Once island had seeds that had hard shells, so the finches developed sharp beaks to crack the shells. Other finches from another island didn’t because their seeds are easy to eat as they are. If you put a finch from the easy seed island onto the tough shell seed island, it would either die or starvation or evolve to develop a beak to eat the seeds.
Natural selection helped the finches evolve to develop the favorable traits that would help them survive on their own respective islands and resources.
S&EP: SP2 Using Models
GoFormative used simulations that helped me study natural selection. Using this simulation on the Explorelearning Gizmos, I was able to pretend to be a bird and practice trying to catch peppered moths on light and dark trees. This simulation and the graphs/charts helped me understand how the camouflaged moths were able to stay hidden from birds more than the exposed ones. This model was very helpful because I was able to see the graphs that were made based on the number of moths I ‘caught’ during the simulation.
XCC: Structure and Function
Natural selection helped the finches on the islands evolve into a structure that was better suited to their environment. Each of the finches had a different structure based on their island. A finch on an island that had tougher seeds would have a sharper beak in their structure. A finch on an island that had lots of insects would have a more delicate and longer beak to pull bugs out of holes. The finches don’t need to crack thick shells, so their delicate beaks would not be able to open the seeds. The finches with the sharper beaks wouldn’t be able to reach bugs in the holes because their beaks would not be long or thin enough. The way the finches are built directly affects how they survive and function. If the finch is not built to crack seeds, it will die if it is placed on the seedy island. If the finch has a wider and sharper beak than another finch, it is less likely to survive on a buggy island than a finch with a thinner beak. If the finch is not built for the environment, it will not be able to survive.
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