Evidence for Evolution by Natural Selection

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Evidence for Evolutionby Natural Selection
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What is evolution?

• Evolution is the gradual change in a species over
  time.

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Isnt evolution just a theory?
A theory is a ____________, _______, explanation
of phenomena that have occurred in the natural
world, like the theory of __________________,
________, and _____________.
well-supported
testable
gravitational attraction
cell theory
atomic theory
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ons/apple_falling.gif
http//sixthsense.osfc.ac.uk/chemistry/atomic_stru
cture2/atom.gif
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Evidence supporting evolution

• Fossil record
• Anatomical record
• Molecular record

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1. Fossil record

• Fossils show a series of organisms have lived on
  Earth over a long period of time

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Fossils tell a story
the Earth is old
Life is old
Life on Earth has changed
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Evolution of birds
Todays organisms descended from ancestral species

• Fossil of Archaeopteryx
• lived about 150 mya
• links reptiles birds

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We found the fossil!
Land Mammal
Where are theintermediate fossils?
Someones idea of a joke!
Ocean Mammal
But the jokes on them!!
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2. Anatomical record
Animals with different structures on the surface
But when you look under the skin
It tells an evolutionary story of common ancestors
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Compare the bones

• The same bones under the skin
• limbs that perform different functions are built
  from the same bones

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Homologous structures

• Structures that come from the same origin
• homo- same
• -logous information
• Forelimbs of human, cats, whales, bats
• same structure
• on the inside
• different functions
• on the outside
• evidence of common ancestor

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Vestigial organs

• Hind leg bones on whale fossils

Why would whales have pelvis leg bones if they
were always sea creatures?
Because they used to walk on land!
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Vestigial organs

• Structures on modern animals that have no
  function
• remains of structures that were functional in
  ancestors
• evidence of change over time
• some snakes whales have pelvis bones leg
  bones of walking ancestors
• eyes on blind cave fish
• human tail bone

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Comparative embryology

• Development of embryo tells an evolutionary story
  
• similar structures during development

all vertebrate embryos have a gill pouch at one
stage of development
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3. Molecular record

• Comparing DNA protein structure
• everyone uses the same genetic code (DNA)!

• compare common genes
• compare common proteins

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Building family trees

• Closely related species are branches on the tree
  coming from a common ancestor

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Rate Yourself

• 4 Apply concepts of natural selection and
  evolution by creating a scenario that
  demonstrates the ideas
• 3 Explain how natural selection leads to
  evolution.
• 2 Describe how the evidence supports evolution.
• 1 Identify evidence for evolution.