Charles Darwin and Natural Selection

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Charles Darwin and Natural Selection
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Darwins Ideas Influenced by

• Voyage on the Beagle (1831-1836)
• Lamarcks Theory of Evolution
• Also influenced by

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Geologists James Hutton and Charles Lyell

• Hutton
• Processes that form rock, mountains, and valleys
  are very slow
• Earth is much more than a few thousand years old
• Lyell
• Geological processes we observe now have occurred
  for millions of years
• Explains why marine fossils are at tops of
  mountains

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Thomas Malthus, Economist

• Babies born faster than people dying
• If population growth continued, people would run
  out of food, water and space
• War, famine and disease prevents this

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Fossils
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Artificial Selection

• Breeders select best traits to produce next
  generation

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Darwins Theory of Evolution by Natural Selection

• Living things overproduce

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Darwins Theory of Evolution by Natural Selection

• There is variation among offspring

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Darwins Theory of Evolution by Natural Selection

• There is a struggle to survive

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Darwins Theory of Evolution by Natural Selection

• Those that survive are most fit

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Natural Selection Survival of the Fittest

• Fitness ability to survive and reproduce
• Fitness is the result of adaptations inherited
  characteristics that increase an organisms
  chance of survival

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Descent with Modification

• Over time, natural selection produces organisms
  with different structures
• Todays species look different from their
  ancestors
• Each species descended with changes over time

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Descent with Modification

• Implies that all living things are related to one
  another
• COMMON ANCESTOR