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Evolution and Darwin - extinct but Darwin extended the...

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Evolution and Darwin Population Speciation This portion of Darwin's theory states that within a population, change in a species occurs as the balance of hereditary characteristics shifts across that population. This differs from Lamarck's idea that each individual in the population must undergo the same change. According to Lamarck, all giraffes living under tall trees would develop long necks. According to Darwin, some would randomly be born with long necks, this hereditary trait would gradually spread throughout the population. Natural selection Natural selection is often called the most unique part of Darwin's theory. Competition, also called the struggle for life, had been thought of as a reason that a given species might succeed or go
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Unformatted text preview: extinct, but Darwin extended the understanding to change within a species. To continue the example of giraffes: when a giraffe is born with a longer neck than its fellows, it gains an advantage because it is able to reach more food. The long-neck giraffe is therefore stronger, lives longer, and more likely to have offspring. These offspring are born with the same long neck as their parent, though some might have even longer necks. The cycle continues. The theory of natural selection depends on five postulates: • Individuals are variable. • Some variations are passed down. • More offspring are produced than can survive. • Survival and reproduction are not random. • The history of earth is long....
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