Origin of Species

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Origin of Species

• Special creation- each of the different kinds of
  organisms were created in their present form.
• Inheritance of acquired characteristics- the
  modifications an organism acquires during its
  lifetime can be passed along to its offspring.

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Charles Darwin- 1831 HMS Beagle
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Observations by Darwin in the Galápagos

• Two Important Observations
• 1) Plants and animals on the island were similar
  to those on the nearby mainland.
• 2) Phenotypic variation occured between organisms
  from island to island.

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Darwin repeatedly emphasized two points in his
book.

• Species evolve from other species. He termed this
  "descent with modification"
  Evolution
• The mechanism or driving force of evolution is
  Natural Selection

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Darwin cited the following in support of Natural
Selection

• Variation occurs in every group of plants and
  animals.
• All organisms have the potential to
  over-reproduce.
• Natural resources are limited.
• Only the most adapted to the local environment
  survive and pass along traits to the next
  generation.

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Darwin's own sketches of Galápagos finches. (1)
Large ground finch Geospiza magnirostris(2)
Medium ground finch Geospiza fortis(3) Small
tree finch Camarhynchus parvulus (4) Warbler
finch Certhidea olivacea
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Genetic Drift