Chapter 10 Notes

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Chapter 10 Notes

• Evolution Natural Selection

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CHARLES DARWIN

• started out as a medical student, however, he
  didnt like being a doctor
• trained to be a minister
• recommended by a professor to work on the HMS
  Beagle

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• 5 years he worked on board the Beagle as a
  naturalist
• collected thousands of plants and animals
  fossils

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Darwins Finches

• idea that species do not stay constant
• idea that species change over time and give rise
  to new species
• collected several species of finches from the
  Galápagos islands
• these finches were similar in many ways but
  different in how they get food

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• Darwin attributed the differences in bill size
  and feeding habits among these finches to
  evolution that occurred after their ancestors
  migrated to the Galápagos islands

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• change in species over time is Theory of
  Evolution

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MECHANISM FOR EVOLUTION

• for 20 years Darwin gathered evidence to support
  his ideas about evolution
• On the Origin of Species by Means of Natural
  Selection was published in 1859
• the main point of his book organisms with
  traits well suited to an environment are more
  likely to survive produce more offspring then
  organisms w/o these favorable traits

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EVIDENCE FOR EVOLUTION
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1.) Study of fossils

• fossil traces any dead organisms
• EX. Tracks/footprints, insects trapped in
  sap/resin, impressions, bones
• dating fossils measure radioactive decay which
  is the breakdown of radioactive atoms in
  rocks

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• half life time for ½ of the radioactive atoms
  to decay
• EX half-life of carbon-14 5,730 yrs
• 12g of (C-14)? 6g of (C-14)?3g of
  (C-14)
• 5,730 yrs 11,460 yrs
• radioactive dating using the amount of radio
  active element in rock or fossil to determine age.

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2.) Transitional forms

• Intermediate stages between older newer
  species
• See Fig 10-4

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3.) Comparing Organisms

• homologous structures parts that share a
  common ancestor
• EX. forelimbs in birds, dolphins, humans

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• vestigial structures structures with no
  function
• EX. whales pelvis

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• Developmental patterns
• looking at similarity in embryonic
  development.

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4.) Knowledge DNA proteins

• Different organisms have very similar proteins or
  DNA sequences.

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NATURAL SELECTION

• Key factor for natural selection is
  environmentthe environment selects which
  organisms survive and reproduce more often.

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• Using Table 10-1, explain how natural selection
  could drive the evolution of long-necked giraffes
  from short-necked ancestors.

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Does Evolution Occur in Spurts?
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gradualism

• the hypothesis that evolution occurs at a slow,
  constant rate

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punctuated equilibria

• the hypothesis that evolution occurs at
  irregular rates short periods of rapid species
  formation followed by long periods with little or
  no evolution.