Natural selection occurs because

Natural selection occurs because - (running speed for...

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Natural selection occurs because 1. Individuals within a population vary; they are not all identical. 2. Some variants are “better” than others. As a result, they have more reproductive success. 3. The traits that vary are heritable. If the above three items are true, then the “better” individuals will have more success reproducing and will have more offspring. In successive generations, more offspring will have the better traits; the population will change. These items are discussed below. Variation For many traits that occur in a population , individuals are often not all identical. For example, if running speed were measured, some individuals would likely be able to run faster than others but most individuals would probably be intermediate. If number of individuals is plotted against the trait in question
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Unformatted text preview: (running speed for example), a graph like the one shown is often produced. We would get a similar bell-shaped curve if we plotted height, weight , performance on exams, etc. Some Variants are Better Some individuals are bound to be better than others. Perhaps their body structure allows them to escape predators better or to find food faster or to better provide for their young. For example, suppose that the faster-running animals diagrammed below are better able to escape predators than the slower ones. You would expect that more of the faster ones would survive and reproduce than the slower ones. The slower rabbits will not reproduce as much because predators kill them more than they kill the faster rabbits....
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Natural selection occurs because - (running speed for...

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