Patterns of Evolution

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Patterns of Evolution
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Mass Extinctions

• 99 of species that ever lived are extinct
• usually occurs at steady rate, but can happen in
  spurts
• asteroid collision
• cosmic dust enters atmosphere and blocks the
  sunlight.
• layer of iridium in rocks
• (only found in space rocks)

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Meteor vs. Meteorite
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Adaptive Radiation

• many species from one common ancestor
• Darwins finches
• after dinos died out it sparked AR of
  ___________
• Also called Speciation

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Darwins Finches
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Darwins Finches
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Convergent Evolution

• diff. places or times, but similar ecology
• Ex Australian mammals vs. N. Am.
• Ex. Darwins finches / woodpeckers

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Pangaea
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Gondwanaland
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Convergent Evolution
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Convergent Evolution
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Convergent Evolution
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Coevolution

• respond to changes in each other (time)
• orchids / moth - feeding tube (fig. 17-24)
• orchids / male insects mating
• List examples

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Coevolution -- Leafcutter Ants (513)
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Coevolution
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Coevolution
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Punctuated Equilibrium

• Punctuated equilibrium is when a single gene
  "flips the master switch"
• compare/contrast w/ gradualism
• What would fossil record look like?
• figure 17-25

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Remember.

• Our definition of Evolution
• A change
• In genetics
• Over time
• If its a gradual process over time, what should
  the fossil record indicate?

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Gradualism vs. Punctuated Equilibrium
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Punctuated EquilibriumVideo (120)
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Developmental Genes

• -body plans
• Example genes in thorax of insect embryo
  dictate legs. We have similar genes in the
  analogous portion of our embryos that dictate our
  arms / legs.

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HOX Genes Cambrian Explosion
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HOX Genes

• Eyeless fruit fly gets eye gene from a mouse and
  develops fruit fly eyes.
• What does this suggest?

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HOX Genes
34-day old human embryo