Ch25

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Ch25

  1. 1. Evolution Chapter 25 Great Idea: All life on Earth evolved from single-celled organisms by the process of natural selection.
  2. 2. Chapter Outline <ul><li>The Fact of Evolution </li></ul><ul><li>Chemical Evolution </li></ul><ul><li>Natural Selection and the Development of Complex Life </li></ul><ul><li>The Evolution of Human Beings </li></ul>
  3. 3. The Fact of Evolution
  4. 4. The Fact of Evolution <ul><li>Evolution </li></ul><ul><ul><li>Ongoing process of change </li></ul></ul><ul><li>Scientists accept evolution as fact </li></ul><ul><ul><li>Debate various theories </li></ul></ul>
  5. 5. The Fossil Record <ul><li>Fossils </li></ul><ul><ul><li>Organism’s hard parts preserved </li></ul></ul><ul><ul><ul><li>Turned to rock </li></ul></ul></ul><ul><ul><ul><li>Replaced by minerals </li></ul></ul></ul><ul><li>Fossil record </li></ul><ul><ul><li>Fossils found, catalogued, and analyzed </li></ul></ul><ul><ul><li>Shows transitions </li></ul></ul><ul><ul><li>Incomplete </li></ul></ul>
  6. 6. The Fossil Record – cont. <ul><li>Three key ideas </li></ul><ul><ul><li>Older fossils more different </li></ul></ul><ul><ul><li>Increasing complexity with time </li></ul></ul><ul><ul><li>Most species have gone extinct </li></ul></ul>
  7. 7. Wide Variety of Fossils
  8. 8. Fossil Trilobites
  9. 9. The Biochemical Evidence <ul><li>DNA </li></ul><ul><ul><li>Evidence for evolution </li></ul></ul><ul><ul><li>Changes slowly </li></ul></ul><ul><ul><li>Also compare amino acid sequences </li></ul></ul><ul><ul><ul><li>Cytochrome c </li></ul></ul></ul><ul><ul><ul><ul><li>Humans and chimps identical </li></ul></ul></ul></ul><ul><ul><ul><ul><li>Rattlesnake 86% overlap </li></ul></ul></ul></ul>
  10. 10. Evidence from Anatomy: Vestigial Organs <ul><li>Vestigial organs </li></ul><ul><ul><li>Internal features </li></ul></ul><ul><ul><li>No useful function </li></ul></ul><ul><li>Examples </li></ul><ul><ul><li>Appendix: humans </li></ul></ul><ul><ul><li>Wings: penguins </li></ul></ul><ul><ul><li>Hind legs: whales </li></ul></ul>
  11. 11. Wings of a Penguin Are Vestigial Organs
  12. 12. Chemical Evolution
  13. 13. Chemical Evolution <ul><li>Chemical evolution </li></ul><ul><ul><li>Process of combining rocks, water and gases </li></ul></ul><ul><li>Miller-Urey experiment </li></ul><ul><li>Formation of cell </li></ul><ul><ul><li>Still unknown </li></ul></ul>
  14. 14. Miller-Urey Experiment
  15. 15. Black Smokers <ul><li>Black Smokers </li></ul><ul><ul><li>Deep-ocean floor </li></ul></ul><ul><ul><li>Vents of mineral rich hot water </li></ul></ul><ul><ul><li>Diverse ecosystem </li></ul></ul><ul><ul><ul><li>Most primitive bacteria </li></ul></ul></ul><ul><li>Hydrothermal zones </li></ul><ul><ul><li>Site of life’s origin? </li></ul></ul><ul><ul><ul><li>Protected </li></ul></ul></ul><ul><ul><ul><li>Ideal chemical environment </li></ul></ul></ul>
  16. 16. Black Smokers
  17. 17. RNA Enzymes <ul><li>Early life was simpler </li></ul><ul><ul><li>RNA catalyzed reactions </li></ul></ul><ul><ul><li>Created proteins </li></ul></ul><ul><ul><li>Proteins led to DNA </li></ul></ul>
  18. 18. The Window of Opportunity <ul><li>Chemical processes </li></ul><ul><ul><li>Occurred rapidly </li></ul></ul><ul><li>Recent discoveries </li></ul><ul><ul><li>Schopf </li></ul></ul><ul><ul><ul><li>Evidence of life 3.5 billion years ago </li></ul></ul></ul><ul><li>First cell </li></ul><ul><ul><li>4.0-3.5 billion years ago </li></ul></ul>
  19. 19. The First Cell <ul><li>First cell </li></ul><ul><ul><li>No competition </li></ul></ul><ul><ul><li>Multiplied rapidly </li></ul></ul><ul><li>Special characteristics </li></ul><ul><ul><li>20 amino acids </li></ul></ul>
  20. 20. Science by the Numbers <ul><li>Cell division </li></ul>
  21. 21. The Ongoing Process of Science <ul><li>Did life also originate on Mars? </li></ul><ul><ul><li>Evidence from a meteorite </li></ul></ul>
  22. 22. Natural Selection and the Development of Complex Life
  23. 23. Natural Selection <ul><li>Charles Darwin </li></ul><ul><li>Natural Selection </li></ul><ul><ul><li>Variation in populations </li></ul></ul><ul><ul><ul><li>Some variation heritable </li></ul></ul></ul><ul><ul><li>More individuals born than will survive </li></ul></ul><ul><li>Adaptation </li></ul><ul><li>Artificial selection </li></ul>
  24. 24. Dog Breeds
  25. 25. Cobalt-Winged Parakeets
  26. 26. Science in the Making <ul><li>The reception of Darwin’s theory </li></ul><ul><ul><li>On the Origin of the Species </li></ul></ul><ul><li>Alfred Russell Wallace </li></ul>
  27. 27. Charles Darwin
  28. 28. The Story of Life <ul><li>First cell </li></ul><ul><ul><li>Natural selection </li></ul></ul><ul><ul><ul><li>Mutations </li></ul></ul></ul><ul><li>Mutations </li></ul><ul><ul><li>Random </li></ul></ul><ul><ul><li>Most not beneficial </li></ul></ul><ul><li>Environment </li></ul><ul><ul><li>Impacts evolution </li></ul></ul>
  29. 29. The Story of Life – cont. <ul><li>Eukaryotes </li></ul><ul><li>Colonies </li></ul><ul><li>Hard shell </li></ul><ul><ul><li>Cambrian explosion </li></ul></ul>
  30. 30. A Fossil Microbe
  31. 31. Rock with Fossils
  32. 32. Major Steps in the Evolution of Life
  33. 33. Geological Time
  34. 34. The Ongoing Process of Science <ul><li>The evolution of whales </li></ul><ul><ul><li>What does the fossil record tell us? </li></ul></ul>
  35. 35. Mass Extinctions and the Rate of Evolution <ul><li>Rate of extinction </li></ul><ul><ul><li>10%-20% extinct in 5-6 million years </li></ul></ul><ul><li>Mass extinctions </li></ul><ul><ul><li>30%-90% extinct </li></ul></ul><ul><li>Mechanisms </li></ul><ul><ul><li>Asteroid </li></ul></ul><ul><li>Evolution </li></ul><ul><ul><li>Gradualism </li></ul></ul><ul><ul><li>Punctuated equilibrium </li></ul></ul>
  36. 36. Extinction Events
  37. 37. Giant Crater near the Yucatan Peninsula
  38. 38. Chesapeake Bay Impact Drilling Site
  39. 39. The Evolution of Human Beings
  40. 40. “ Lucy”
  41. 41. Neanderthal Man
  42. 42. Thinking More about Evolution <ul><li>Young-earth creationism </li></ul><ul><li>Intelligent design </li></ul>

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