Principles of Evolution

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Principles of Evolution
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New Evidence Eroded View of Creationism

• New lands
• revealed diversity of life
• Africa, Asia, Americas
• Many different species some closely resembled
  each other
• Fossil Discoveries
• Fossils remains of dead organisms (in rock,
  petrified bones and wood, shells, impressions of
  body forms
• showed life changed over time

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(a)
(b)
(c)
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How Do We Know That Evolution Has Occurred?

• Fossils
• Comparative Anatomy
• Embryology
• Biochemistry and Genetics

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Evidence of evolution

• Fossils
• - Transitional forms are evidence of
  evolutionary change
• - Series of fossils have been found showing new
  species have evolved and replaced earlier species
• - Controversies over the interpretation of
  fossil data
• Dating of fossils
• Do fossils really show transitional forms?

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Biogeography

• The great continent of Pangeae divided into our
  current continents.
• Biogeography is the study of the distribution of
  plants and animals on the earth. Continental
  drift aided in the distribution of fossils and
  species of organisms.

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Evidence of evolution

• Comparative anatomy
• Comparing the bodies of organisms to look for
  similarities and differences
• Homologous structures
• Structures in the anatomy with the same
  evolutionary origin, but may have different
  functions

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Evidence of evolution

• Vestigial structures
• Structures serve no apparent purpose but are
  homologous to structures in related organisms

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Evidence of evolution

• Analogous structures
• Structures that have same functions and appear
  similar, but are different in anatomies
• Convergent evolution
• Similar structures have evolved due to
  environmental pressures not common ancestry

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Analogous Structures
Wings
Streamlined shape
(a)
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Evidence of evolution

• Comparative embryology
• All vertebrate embryos look similar to one
  another in early development, with the
  development of a tail and gill slits

Pharyngeal slits, color-coded here, exist in the
embryos of these five vertebrate animals (a) sea
lamprey, (b) pond turtle, (c) chicken, (d)
domestic cat, and (e) human being. The common
structure is evidence that all five evolved from
a common ancestor. (Adapted from M. K.
Richardson, 1997.) Krogh, Biology A Guide to the
Natural World 2nd ed.
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Evidence of evolution

• Comparative biochemistry and molecular biology
• All cells have DNA, RNA, ribosomes, the same 20
  amino acids, and use ATP as an energy carrier
• DNA similarities

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Molecular data
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What is the evidence that populations evolve by
natural selection?

• Artificial selection
• Breeding domestic plants and animals to produce
  specific features
• Dogs
• If we can breed such different dogs in a few
  thousand years, it is entirely possible for
  natural selection can occur and produce many
  organisms in hundreds of millions of years

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Present-day evolution
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Present-day evolution