Chapter 24 The Origin of Species

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Chapter 24The Origin of Species
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Question?

• What is a species?
• Comment - Evolution theory must also explain how
  species originate.

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Two Concepts of Species
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Morphospecies
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Problem

• Where does extensive phenotype variation fit?

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Two Schools
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Biological Species
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Key Points
Heaven Scent an F1 hybrid between 2 species,
but sterile.
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Morphospecies Biological Species
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Speciation Requires

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Reproductive Barriers
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Main Types of Barriers
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Prezygotic - Types
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Habitat Isolation
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Behavioral Isolation
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Temporal Isolation
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Mechanical Isolation
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Gametic Isolation
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Postzygotic Types
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Reduced Hybrid Viability
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Reduced Hybrid Fertility
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Hybrid Breakdown
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Other Concepts of Species
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Recognition Species Concept
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Cohesion Species Concept
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Ecological Species Concept
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Evolutionary Species Concept
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Comment

• AP exam will focus on morphological and
  biological species concepts.

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Modes of Speciation
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Allopatric Speciation
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Example
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Another Example
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Conditions Favoring Allopatric Speciation
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Conditions Favoring Allopatric Speciation
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Result
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Comment
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Examples
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Adaptive Radiation
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Mechanism
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When the Environment Saturates
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Sympatric Speciation
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Plants
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Polyploid Types
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Autopolyploid
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Allopolyploid
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Animals
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Gradualism Evolution
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Gradualism Predicts
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Problem
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Punctuated Evolution
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Punctuated Equilibrium
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Predictions
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Predictions
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Possible Mechanism
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Comment
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Origin of Evolutionary Novelty
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Exaptation
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Heterochrony
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Allometric Growth
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Paedomorphosis
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Ex - Homeosis
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Gene Duplications
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Future of Evolution ?

• Look for new theories and ideas to be developed,
  especially from new fossil finds and from
  molecular (DNA) evidence.

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Evolutionary Trends

• Evolution is not goal oriented. It does not
  produce perfect species.
• Remember species survive because of their
  adaptations. They dont adapt to survive.

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Summary

• Be able to discuss the main theories of what is a
  species.
• Know various reproductive barriers and examples.

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Summary

• Know allopatric and sympatric speciation.
• Be able to discuss gradualism and punctuated
  equilibrium theories.

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Summary

• Recognize various ideas about the origin of
  evolutionary novelties.