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Theory of Evolution
       part II
Evidence for Evolution

Inferences about the
history of life are based on
the assumptions of certain
geological principles.
Nicolaus Steno (1638-1687)



Steno's Law of Superposition
James Hutton (1726-1797)
Uniformitarianism:   “ The present is the key to the
past”

        the fundamental principle tha...
Charles Lyell (1797-1875)

 first geologic time scale


 proposed an older earth
 than was previously
 accepted


 Lyell’s ...
Relative Age generally relies on position
within the geologic column in reference
to index fossils.



Absolute Age genera...
The amount of time it takes for 1/2 of a
radioactive isotope to decay to non-
radioactive form is known as half-life.
Generalized presentation of Geologic
time and the appearance of life forms.
The Fossil Record

 paleontologist- scientist who study fossils

 Fossils are the preserved remains or
 traces of once liv...
The Fossil Record

 While there are gaps, paleontologists can offer
 a relatively clear picture of the evolution of
 many o...
How fossils form

 frozen in ice

 trapped in hardened tree sap

 peat bogs, quicksand, tar pits

 most are found in sedim...
Problems in Assembling
the Fossil Information

 all of the fossil “puzzle pieces” are not in
 place

 many organisms may l...
Evidence from Living
Organisms

homologous
structures- similar
structures adapted
to different
environments
Evidence from Living
Organisms
 vestigial organs- organs or structure that
 seem to serve no useful purpose
Evidence from Living
Organisms

 Structural homologies support common
 descent with modifications

 If organisms had arisen...
Evidence from Living
Organisms


 similarities in embryo development with
 the passage of time, embryos become
 more dissi...
Evidence from Living
Organisms
 Modern Synthesis

  Integrates the new genetics with
  natural selection.

  Ancestral rel...
Protist   Fungi   Plants
               Archeabacteria
                                                    Animals
Eubacte...
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Evolution part II

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Lecture slides for Mr. Mason's Biology I, Hon class

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Evolution part II

  1. 1. Theory of Evolution part II
  2. 2. Evidence for Evolution Inferences about the history of life are based on the assumptions of certain geological principles.
  3. 3. Nicolaus Steno (1638-1687) Steno's Law of Superposition
  4. 4. James Hutton (1726-1797) Uniformitarianism: “ The present is the key to the past” the fundamental principle that geological processes and natural laws now operating to modify the Earth's crust have acted in much the same manner and with essentially the same intensity throughout geologic time, and that past geologic events can be explained by forces observable today;
  5. 5. Charles Lyell (1797-1875) first geologic time scale proposed an older earth than was previously accepted Lyell’s text influenced Darwin’s ideas
  6. 6. Relative Age generally relies on position within the geologic column in reference to index fossils. Absolute Age generally relies on the rate of decay of various radioactive isotopes.
  7. 7. The amount of time it takes for 1/2 of a radioactive isotope to decay to non- radioactive form is known as half-life.
  8. 8. Generalized presentation of Geologic time and the appearance of life forms.
  9. 9. The Fossil Record paleontologist- scientist who study fossils Fossils are the preserved remains or traces of once living organisms the cumulative collection of fossils represents the “Fossil Record”
  10. 10. The Fossil Record While there are gaps, paleontologists can offer a relatively clear picture of the evolution of many organisms. tells us of major changes in climate and geography as environments changed over earth’s history, changes in living things followed
  11. 11. How fossils form frozen in ice trapped in hardened tree sap peat bogs, quicksand, tar pits most are found in sedimentary rock
  12. 12. Problems in Assembling the Fossil Information all of the fossil “puzzle pieces” are not in place many organisms may live and die without leaving a trace fossil bearing rocks must be exposed to weathering
  13. 13. Evidence from Living Organisms homologous structures- similar structures adapted to different environments
  14. 14. Evidence from Living Organisms vestigial organs- organs or structure that seem to serve no useful purpose
  15. 15. Evidence from Living Organisms Structural homologies support common descent with modifications If organisms had arisen independently, there would be very little chance of these similarities Each new species adapted what was present in the species before it.
  16. 16. Evidence from Living Organisms similarities in embryo development with the passage of time, embryos become more dissimilar Biochemical similarities- DNA, ATP
  17. 17. Evidence from Living Organisms Modern Synthesis Integrates the new genetics with natural selection. Ancestral relationships (phylogeny) modeled as a branching tree. Cladistics - branching tree cladagram from comparing shared characters to derived characters
  18. 18. Protist Fungi Plants Archeabacteria Animals Eubacteria Common Ancestor

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