Darwins Natural Selection : A Mechanism of Evolution

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Darwins Natural Selection A Mechanism of
Evolution

• Section 14.3

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Natural Selection

• Regional and timely
• Adapts organisms to their local environment
• Environmental factors vary from place to place
  time to time? adaptation in one situation may be
  useless in another
• Example Biston betularia? peppered moth

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Peppered Moth

• England ? two varieties? dark light
• 1850? almost all were light? industrial
  revolution? pollution? tree trunks turned black?
  light moths became easy prey
• Dark survived reproduced
• End of century ? almost all were dark

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Biston betularia peppered moth
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Populations

• A group of individuals of the same species living
  in the same place at the same time
• Mainland animal species colonizes a chain of
  distant and isolated islands? separate
  population.
• These populations adapt to their local
  environments.
• Over time, the isolated populations would become
  more and more different.
• And over many generations, the populations could
  become different enough to be separate species.

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Darwins Finches? adapted to different food
sources ?beak Structures
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Variation

• Differences among members of the same Species

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Adaptation

• Inherited trait that Improves the Chances Of
  Survival Reproduction
• Structural? mimicry? organism copies the
  appearance of another species
• Physiological? changes in the organisms metabolic
  process? penicillin? drug resistant bacteria
• Behavioral? inherited behavior pattern that
  allows organism to survive

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Adaptation- Mimicry

• Viceroy(extra black lines on wings)? not bitter,
  look act like Monarchs ?birds avoid them

• Monarch? tastes bitter? birds avoid them because
  they get sick

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Adaptation Camouflage

• Protective adaptation that allows an organism to
  blend into its surroundings
• The better the camouflage, the more likely it is
  for the organism to survive and reproduce

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Adaptation Camouflage
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Artificial Selection

• Selective breeding of domesticated plants and
  animals to produce offspring with genetic traits
  that humans value.

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From Wild Mustard to our Table
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Pesticides- Natural Selection in Action

• Spraying crops ?kill insect pests? favored the
  reproduction of insects with inherited resistance
  to the poisons