Evidence for Evolution

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Evidence for Evolution

• Biology I

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Fossil Record

• SIMPLE to COMPLEX
• Of course, the fossil record is not complete
  not every organism gets fossilized
• Still, there are LOTS of fossils and a simple to
  complex trend is clearly shown.
• Also, transition organisms

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Fossil Record Transition Organism

• Tiktaliik Rosea
• Transition fossil - from fish to amphibian
• Click here for
• more

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Comparative Anatomy

• Comparing the anatomical structures of different
  organisms to determine their relatedness
• Homologous structures
• structures in different spcecies
• May look different superficially
• Similarities indicate a COMMON ORIGIN / COMMON
  ANCESTOR

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Example Homologous Structures

• Bones of mammals below show common ancestry

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Embryology

• Embryology the study of embryos
• Organisms that are more closely related share
  similar deveopmental patterns in their embryos.

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Vestigial Organs

• Organs that have no function in the organism in
  which they are found, but DID have a function in
  an ANCESTOR
• Why would an organism waste energy maintaining a
  useless organ?
• They wouldnt, except that it must be a left over
  from an ancestor who DID use the organ
• Supports the idea of evolutionary change

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Example Vestigial Structure

• Human Tailbone

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Vestigial Organ Whale hindlimb
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also in snakes
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Molecular Biology

• Analysis of DNA shows us exactly who is closely
  reltaed to whom by seeing how similar the
  letters of the DNA molecules are between species

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Molecular Biology Example

• Humans and Chimps share 98 of DNA

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Biogeographical Evidence

• Galapagos animals similar to those on mainland S.
  America Why?
• Suggests organisms from S. America came to the
  islands and changed to fit their new environment
• Otherwise, why wouldnt they be totally different
  the environment is certainly totally different