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NATURAL SELECTION. On the Origin of Species. Darwin delayed publishing for over 25 years (largely due to social influences) He left out his hypotheses about human evolution. Darwin proposed “Natural Selection” and “Survival of the Fittest”
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On the Origin of Species • Darwin delayed publishing for over 25 years (largely due to social influences) • He left out his hypotheses about human evolution. • Darwin proposed “Natural Selection” and “Survival of the Fittest” • His theories form the current basis for evolution and the study of biological science
Natural selection • Competition for resources – food, space, mates
Natural selection • Survival of the fittest – variations within genes may provide some organisms with an advantage over others • “The individual best suited to their environment will survive to reproduce.” • Ex – camouflage, mimicry, efficiency of photosynthesis, hunting in packs. • Over time, the population changes due to the frequency of inherited traits.
Real Life Scenario: Industrial revolution increases pollution in the air. The pollution can be seen discoloringthe environment. Peppered moths saw a big change in favoredcolor. Before Industrial Revolution After
Bigger and stronger is not always better! misconceptions
4 Components of Natural Selection • Natural Variationin DNA. • DNA is inherited. • More individuals are born • than can survive (struggle for existence). • 4. Variable “fitness” leads to the best suited organisms surviving to reproduce.