How Did Darwin Explain Evolution?

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How Did Darwin Explain Evolution?

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On The Origin Of Species

• Published in 1859 by Charles Darwin
• Explained his theory of evolution by Natural
  Selection

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Natural Variation andArtificial Selection

• Natural variations are differences among
  individuals of a species. (For example some
  horses are slow and some are fast)
• Selective Breeding (Artificial Selection) is
  allowing only the fastest horses, the largest
  hogs and the cows that give the most milk to
  produce offspring.
• This produces faster horses, larger hogs, and
  cows that make more milk

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Darwins Theory Of EvolutionBy Natural Selection

• The Struggle for Existence
• Survival Of The Fittest
• Descent With Modification

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Struggle For Existence

• Members of each species compete regularly for
  food, living space and other necessities of life.
• For example a faster predator will have and
  advantage over a slower one.

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Survival Of The Fittest

• The ability of an individual to survive and
  reproduce in its environment is called fitness
• Fitness is a result of adaptations
• An adaptation is any inherited characteristic
  that increases an organisms chance of survival
• Individuals that are better suited to their
  environment (have high levels of fitness) survive
  and reproduce most successfully

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Descent With Modification

• Each living species has descended, with changes,
  from other species over time

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Evidence Of Evolution

• Fossil Record
• Geographic Distribution of Living Species
• Homologous Body Structures
• Similarities in Early Development