Theories Of Natural Selection

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As human, we often ask ourselves: where do we come from? Through time, we have tried to answer this question, usually with religious beliefs. However, some people also had their own theory. One of the most known is the theory of evolution and natural selection by Darwin. But, what are natural selection and evolution? Those concepts are often misunderstood. Few people know their different process, the origin of natural selection and the evidence of evolution that we have found.

In the first place, we must understand what evolution is and the way it may occurs to fully understand the theory that goes with it. The definition of evolution is “descents with modifications”. In other words, it means that some species live a modification in their
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Indeed, there are only three simple preconditions for natural selection to happen. First, there must be a variation of trait within a population. This means that some individuals must be different from the other individual (lecture). Those variation are call mutation; they are totally random changes in the DNA(Futuyma, 2004). Then, some individuals must be able to reproduce themselves more easily than other and their trait must also be pass from generation to generation. This last conditions is called heredity. If all of those are respected then natural selection may occurs. Furthermore, this theory is based on the fact that, as there are physical variation in a population, some individuals are going to be more likely to survive to their environment, usually to the lack of resources and the predators, than others and also to reproduce themselves more easily. So, their trait is going to be pass from generation to generation until the entire population is adapted. However, it is important to understand that natural selection is not random. It is nature that decide which individuals are going to survive and reproduce themselves (lecture). In brief, it is the individuals who adapted themselves the most to their environment that will …show more content…
Obviously, the evidence that Darwin use to explain his theory are still use today, such has fossils, homologies and evidence by example. First, fossils help us to see the change overtime of different species with their extinct ancestors. Take the case of whales, of which we found that the ancestors had teeth by looking at their fossils. It was another indication of evolution, because modern whales don’t have teeth (WDNK, 2001). Then, there are homologies; it is the link of similar characteristic in different species due to common ancestors. This type evidence helped us to explain the fact that, even if they all have different leaves, plants have the same structure. Next, example by evidence is the observation of modern organism’s evolution, like the house sparrows whose size and color changed when this species came in America. Moreover, we also have new type evidence. Distribution to time and space allows us to understand why and how we can find different evidence, by example the marsupial’ fossils, in many continents by looking at the history of life. But, our biggest improvement is to be able to look at species DNA. It helped us to understand more the connections and the variation of species (lecture). Finally, all those evidence clearly support the theory of

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