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  • 1. AIM: How can we know that evolution has actually occurred? Warm – up: How does Darwin explain the presence of organisms alive today?
  • 2. LaMarck • Organisms adapted to their environments ØThrough acquired traits ØChange in their lifetime v Use & Disuse: organisms lost parts of their body because they did not use them (like the missing eyes and digestive system of the tapeworm) v Perfection with Use & Need: the constant use of an organ leads to an increase in size of that organ ØTransmit acquired characteristics to next generation
  • 3. LaMarck • Organisms adapted to their environments ØThrough acquired traits ØChange in their lifetime v Use & Disuse: organisms lost parts of their body because they did not use them (like the missing eyes and digestive system of the tapeworm) v Perfection with Use & Need: the constant use of an organ leads to an increase in size of that organ ØTransmit acquired characteristics to next generation
  • 4. But the fossil record shows…
  • 5. Descent with Modification Darwin’s idea that each species living today arose from a pre-existing species!
  • 6. Hundreds of millions of years passed before atmospheric oxygen levels were high enough to support eukaryotes.
  • 7. Evidence Supporting Evolution
  • 8. Evidence Supporting Evolution • Fossils (descent with modification)
  • 9. Evidence Supporting Evolution • Fossils (descent with modification) • Comparative biochemistry
  • 10. Evidence Supporting Evolution • Fossils (descent with modification) • Comparative biochemistry • Comparative cell biology
  • 11. Evidence Supporting Evolution • Fossils (descent with modification) • Comparative biochemistry • Comparative cell biology • Comparative embryology
  • 12. Evidence Supporting Evolution • Fossils (descent with modification) • Comparative biochemistry • Comparative cell biology • Comparative embryology • Comparative anatomy
  • 13. Fossils as Evidence
  • 14. Fossils as Evidence • A fossil is the remains of organisms that lived in the past.
  • 15. Fossils as Evidence • A fossil is the remains of organisms that lived in the past. • They are preserved by natural processes (in ice, rock, etc.)
  • 16. Fossils as Evidence • A fossil is the remains of organisms that lived in the past. • They are preserved by natural processes (in ice, rock, etc.) • Examples: bones, shells, footprints, imprints
  • 17. Fossils as Evidence • A fossil is the remains of organisms that lived in the past. • They are preserved by natural processes (in ice, rock, etc.) • Examples: bones, shells, footprints, imprints • Generally, found in sedimentary rock that has been quickly covered by silt. Why?
  • 18. How old are fossils?
  • 19. How old are fossils? • Relative dating: Fossils can be dated in correlation with the age of the strata (layer of rock) they are in.
  • 20. How old are fossils? • Relative dating: Fossils can be dated in correlation with the age of the strata (layer of rock) they are in. • Absolute Dating: Using radioactive isotopes (half life) to get a more accurate estimate of age.
  • 21. Problems with Fossils?
  • 22. Problems with Fossils? • Dating is only an approximation
  • 23. Problems with Fossils? • Dating is only an approximation • No fossils of early or soft-bodied organisms
  • 24. Problems with Fossils? • Dating is only an approximation • No fossils of early or soft-bodied organisms • Holes in the fossil record
  • 25. Problems with Fossils? • Dating is only an approximation • No fossils of early or soft-bodied organisms • Holes in the fossil record
  • 26. Problems with Fossils? • Dating is only an approximation • No fossils of early or soft-bodied organisms • Holes in the fossil record So what do scientists turn to?
  • 27. Land Mammal ? ? ? ?
  • 28. Land Mammal ? ? e the ? re ar tes? Whe edia ? In term
  • 29. Land Mammal ? ? e the ? re ar tes? Whe edia ? In term
  • 30. Land Mammal ? ? e the ? re ar tes? Whe edia ? In term
  • 31. Land Mammal
  • 32. 2006 Fossil Discovery of Early Tetrapod • Missing link from sea to land animals
  • 33. 2006 Fossil Discovery of Early Tetrapod • Missing link from sea to land animals
  • 34. Comparative Biochemistry & Cell Biology show that…
  • 35. Comparative Biochemistry & Cell Biology show that… • the genetic code in nucleic acids is almost universal
  • 36. Comparative Biochemistry & Cell Biology show that… • the genetic code in nucleic acids is almost universal • physiological processes follow common metabolic pathways
  • 37. Comparative Biochemistry & Cell Biology show that… • the genetic code in nucleic acids is almost universal • physiological processes follow common metabolic pathways • ATP is the universal form of energy
  • 38. Comparative Biochemistry & Cell Biology show that… • the genetic code in nucleic acids is almost universal • physiological processes follow common metabolic pathways • ATP is the universal form of energy • Organisms that are related often have similar types of proteins and antibodies
  • 39. Comparative Biochemistry & Cell Biology show that… • the genetic code in nucleic acids is almost universal • physiological processes follow common metabolic pathways • ATP is the universal form of energy • Organisms that are related often have similar types of proteins and antibodies
  • 40. Comparative Biochemistry & Cell Biology show that… • the genetic code in nucleic acids is almost universal • physiological processes follow common metabolic pathways • ATP is the universal form of energy • Organisms that are related often have similar types of proteins and antibodies
  • 41. Comparative Biochemistry & Cell Biology show that… • the genetic code in nucleic acids is almost universal • physiological processes follow common metabolic pathways • ATP is the universal form of energy • Organisms that are related often have similar types of proteins and antibodies
  • 42. Comparative Biochemistry & Cell Biology show that… • the genetic code in nucleic acids is almost universal • physiological processes follow common metabolic pathways • ATP is the universal form of energy • Organisms that are related often have similar types of proteins and antibodies
  • 43. Comparative Embryology
  • 44. Comparative Embryology • Species that are known to be closely related show similar embryonic development.
  • 45. Comparative Embryology • Species that are known to be closely related show similar embryonic development. • Inference: The longer two embryos stay looking similar, the more closely related they are.
  • 46. Comparative Anatomy
  • 47. Comparative Anatomy • Study of biological structures in different organisms
  • 48. Comparative Anatomy • Study of biological structures in different organisms
  • 49. Comparative Anatomy • Study of biological structures in different organisms • Homologous structures: structures in different species that have a similar design and position but serve different purposes in species that live in different environments.
  • 50. Comparative Anatomy • Study of biological structures in different organisms • Homologous structures: structures in different species that have a similar design and position but serve different purposes in species that live in different environments. ex. Pentadactyl limb in mammals
  • 51. Comparative Anatomy • Study of biological structures in different organisms • Homologous structures: structures in different species that have a similar design and position but serve different purposes in species that live in different environments. ex. Pentadactyl limb in mammals • Divergent evolution
  • 52. Comparative Anatomy • Study of biological structures in different organisms • Homologous structures: structures in different species that have a similar design and position but serve different purposes in species that live in different environments. ex. Pentadactyl limb in mammals • Divergent evolution
  • 53. Comparative Anatomy • Study of biological structures in different organisms • Homologous structures: structures in different species that have a similar design and position but serve different purposes in species that live in different environments. ex. Pentadactyl limb in mammals • Divergent evolution • Analogous structures: Structure of two unrelated species that can evolve to look alike on the basis that they serve a similar function in a similar environment.
  • 54. Analogous structures
  • 55. Analogous structures
  • 56. Analogous structures • Separate evolution of structures
  • 57. Analogous structures • Separate evolution of structures – similar functions
  • 58. Analogous structures • Separate evolution of structures – similar functions – similar external form
  • 59. Analogous structures • Separate evolution of structures – similar functions – similar external form – different internal structure & development
  • 60. Analogous structures • Separate evolution of structures – similar functions – similar external form – different internal structure & development – different origin
  • 61. Analogous structures • Separate evolution of structures – similar functions – similar external form – different internal structure & development – different origin – no evolutionary relationship
  • 62. Analogous structures • Separate evolution of structures – similar functions – similar external form – different internal structure & development – different origin – no evolutionary relationship Solving a similar problem with a similar solution
  • 63. Analogous structures • Separate evolution of structures – similar functions – similar external form – different internal structure & development – different origin – no evolutionary relationship Don’t be fooled by their looks! Solving a similar problem with a similar solution
  • 64. Vestigial Structures
  • 65. Vestigial Structures • Modern animals may have structures that serve little or no function
  • 66. Vestigial Structures • Modern animals may have structures that serve little or no function – remnants of structures that were functional in ancestral species
  • 67. Vestigial Structures • Modern animals may have structures that serve little or no function – remnants of structures that were functional in ancestral species – evidence of change over time
  • 68. Vestigial Structures • Modern animals may have structures that serve little or no function – remnants of structures that were functional in ancestral species – evidence of change over time • some snakes & whales
  • 69. Vestigial Structures • Modern animals may have structures that serve little or no function – remnants of structures that were functional in ancestral species – evidence of change over time • some snakes & whales show remains of the
  • 70. Vestigial Structures • Modern animals may have structures that serve little or no function – remnants of structures that were functional in ancestral species – evidence of change over time • some snakes & whales show remains of the pelvis & leg bones of
  • 71. Vestigial Structures • Modern animals may have structures that serve little or no function – remnants of structures that were functional in ancestral species – evidence of change over time • some snakes & whales show remains of the pelvis & leg bones of walking ancestors
  • 72. Vestigial Structures • Modern animals may have structures that serve little or no function – remnants of structures that were functional in ancestral species – evidence of change over time • some snakes & whales show remains of the pelvis & leg bones of walking ancestors • human tail bone
  • 73. Vestigial Structures • Hind leg bones on whale fossils
  • 74. Vestigial Structures • Hind leg bones on whale fossils
  • 75. Vestigial Structures • Hind leg bones on whale fossils Why would whales have pelvis & leg bones if they were always sea creatures?
  • 76. ANY QUESTIONS?? This is the time to ask…

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