Chapter 24 The Origin of Species

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Chapter 24The Origin of Species
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Chapter 24The Origin of Species

• Microevolution (you will remember from chapter
  23) is

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Chapter 24The Origin of Species

• Microevolution (you will remember from chapter
  23) is the generation-to-generation change in
  allele frequencies within a species

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Chapter 24The Origin of Species

• Microevolution (you will remember from chapter
  23) is the generation-to-generation change in
  allele frequencies within a species.
• Macroevolution (on the other hand) is the origin
  of new species.

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Chapter 24The Origin of Species

• Macroevolution happens two ways

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Chapter 24The Origin of Species

• Macroevolution happens two ways
• Anagenesis linear evolution
• Cladagenesis branching evolution

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Chapter 24The Origin of Species

• Macroevolution happens two ways
• Anagenesis linear evolution
• Cladagenesis branching evolution

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Chapter 24The Origin of Species

• Macroevolution happens two ways
• Anagenesis linear evolution
• Cladagenesis branching evolution

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Chapter 24The Origin of Species

• What is a species?

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Chapter 24The Origin of Species

• What is a species?
• Reproductive isolation based on prezygotic and
  postzygotic barriers.

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Chapter 24The Origin of Species
Prezygotic barriers

• Habitats
• Mating behaviors
• Mating seasons
• Mechanical incompatibility
• Gamete incompatibility.

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Chapter 24The Origin of Species
Postzygotic barriers

• Embryo is inviable
• Offspring do not survive to adulthood
• Offspring are infertile.

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Chapter 24The Origin of Species

• Species concept does not apply to

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Chapter 24The Origin of Species

• Species concept does not apply to
• Fossils
• Asexual reproduction.

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Chapter 24The Origin of Species

• Other proposed definitions of species

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Chapter 24The Origin of Species

• Other proposed definitions of species
• Ecological
• Morphological
• Pluralistic
• Genealogical.

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Chapter 24The Origin of Species

• Speciation
• Allopatric
• Sympatric

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Chapter 24The Origin of Species

• Speciation
• Allopatric Geographic barriers divide a
  population
• Sympatric

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Chapter 24The Origin of Species

• Speciation
• Allopatric Geographic barriers divide a
  population
• Sympatric New species develop in the midst of
  parent species.

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Chapter 24The Origin of Species

• Causes of sympatric speciation

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Chapter 24The Origin of Species

• Causes of sympatric speciation
• Polyploidy (mostly in plants)
• Host switching (in parasites)
• Nonrandom mating (in polymorphic populations).

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Chapter 24The Origin of Species

• Punctuated equilibrium
• Species change quickly as they bud off from
  parent species, then change relatively little for
  the rest of their existence.

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Chapter 24The Origin of Species

• Evolutionary Novelties

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Chapter 24The Origin of Species

• Evolutionary Novelties
• Modifications of older structures

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Chapter 24The Origin of Species

• Evolutionary Novelties
• Modifications of older structures
• Functions may change or may stay the same.

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Chapter 24The Origin of Species

• Evo-Devo

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Chapter 24The Origin of Species

• Evo-Devo
• Genes that control development play a major role
  in evolution.

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Chapter 24The Origin of Species

• Evo-Devo

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Chapter 24The Origin of Species

• Evo-Devo

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Chapter 24The Origin of Species

• A trend is not a goal.

Evolution is not goal oriented.
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Chapter 24The Origin of Species

• A trend is not a goal.

Evolution is not goal oriented.
.