Natural Selection

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Natural Selection
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Natural Selection explains Evolution and
Adaptation
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Conditions for Natural Selection

• Reproduction
• Heredity (Genes / Replicator)
• Variation in individual characters among
  membersof population (copy mistakes)
• Variation in the fitness of organisms

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Nature is a Struggle for Existence
Atlantic cod
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Nature is a Struggle for Existence
African elephant
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Nature is a Struggle for Existence
After 500 years Darwin 13 000 000
African elephant
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Nature is a Struggle for Existence
After 500 years Darwin 13 000 000 Lord Kelvin
16 000
African elephant
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Nature is a Struggle for Existence
After 500 years Darwin 13 000 000 Lord Kelvin
16 000 Actually 13 000
African elephant
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Nature is a Struggle for Existence
After 500 years Darwin 13 000 000 Lord Kelvin
16 000 Actually 13 000 After 1000 years 81
000 000
African elephant
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Nature is a Struggle for Existence
After 500 years Darwin 13 000 000 Lord Kelvin
16 000 Actually 13 000 After 1000 years 81
000 000 After 2000 years 81 000 000 000 000
000 000 000 000 000 000 000 000 000
African elephant
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Variation is Hereditary Widespread
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Variation is Hereditary Widespread
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Individuals Differ in Fitness
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Variation created by (Undirected) Mutation
Recombination
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Stabilizing
No Selection
Directional
Divergent
Frequency
Fitness
Body Size
Pop Body Size
Time
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Directional Selection ? Size of Salmon
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Stabilizing
No Selection
Directional
Divergent
Frequency
Fitness
Body Size
Pop Body Size
Time
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Stabilizing Selection Birth Weight of Babies
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Stabilizing
No Selection
Directional
Divergent
Frequency
Fitness
Body Size
Pop Body Size
Time
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Divergent Selection Body Size of Darwins Finches
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Stabilizing
No Selection
Directional
Divergent
Frequency
Fitness
Body Size
Pop Body Size
Time
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Natural Selection explains Evolution and
Adaptation
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