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Evidence for Evolution

Explore the four areas of evidence for evolution: the fossil record, anatomy/body structures, embryology, and genetic comparison. Discover how fossils, homologous structures, embryonic similarities, and genetic sequences provide insights into evolutionary relationships.

carolrichards
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Evidence for Evolution

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  1. Evidence for Evolution 4 areas

  2. 1. Fossil Record • 2. Anatomy/body structures • 3. Embryology • 4. Genetic Comparison

  3. 1. Fossil Record • A fossil is any evidence of an organism that lived years ago. • Paleontologists - scientists who study ancient life & fossils

  4. How do fossils form? • Most fossils – sedimentary rock • The animal dies & sinks to sea floor or river bottom • The body begins to decay & is buried under layers of sediment (ex. mud or sand). These layers become rock.

  5. Rapid burial conditions include: • Beach storm deposits, stream flood deposits, tar/mud pits, volcanic lava flows • Environment determines fossil formation; Very few organisms  fossils

  6. Dating Fossils • Relative dating: layers at the bottom are older than those above (approximate age) • Radiometric dating: involves radioactive isotopes C14 & K40 (more exact age)

  7. Relative Dating • Which is the oldest fossil? • Which is the youngest fossil?

  8. Radiometric dating

  9. How fossils show evolution • Age & Behavior patterns • Tracks can show migration • Show changes in climate & geography • What kind of fossils are we finding/type of sediment they are in • Shows evolution & adaptation • Problems: Incomplete fossils & Imperfectly preserved

  10. Increased food source - vast grasslands • Wider, flatter molars better for eating grass • Grasslands made horses more visible to predators • With hoof-like feet horse can run faster & get away from predators

  11. Do you see any similarities among the forelimbs of these animals?

  12. 2. Anatomy/body structures • Homologous structures = modified structure in different groups of organisms • Similar structure, but may have same/different function • Implies common ancestor • Ex. Bones in forelimbs of vertebrates

  13. What is a similar feature of these 2 organisms?

  14. Analogous Structures • Structures w/similar function, but different structure • Shows evolution • NOT common ancestor • Ex: wings – bats, insects, & birds

  15. Talk with a partner • Discuss the differences between homologous and analogous structures and make a chart - compare/contrast the examples given (pictures, diagrams) - compare/contrast definitions

  16. Vestigial Structures • Structures/organs appear to have little/no use • May have been used in ancestor • Indicate evolution

  17. Examples • Ostrich wings • Human appendix • Whales pelvic/hip bones

  18. 3. Embryology • Many different animals – same organs as embryos • Ex: embryos of fish, reptiles, birds & mammals all have gill slits • Suggests common ancestor zebrafish chicken dog human skunk

  19. 4. Genetic Comparisons • Similarities in DNA/RNA sequences • Shows evolutionary relationships • Ex. Organisms use ATP, Same genetic sequences in organisms w/ homologous structures

  20. Which 2 insects are most closely related? • Most distantly related?

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