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Evidence for macroevolution Strongest = Fossil Record order of fossils in sediments

Evidence for macroevolution Strongest = Fossil Record order of fossils in sediments oldest at bottom date with radioisotopes. Fossil Record Find successive change in groups of organisms: "missing links" whale legs & shape. Fossil Record

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Evidence for macroevolution Strongest = Fossil Record order of fossils in sediments

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  1. Evidence for macroevolution • Strongest = Fossil Record • order of fossils in sediments • oldest at bottom • date with radioisotopes

  2. Fossil Record • Find successive change in groups of organisms: "missing links" • whale legs & shape

  3. Fossil Record • Find successive change in groups of organisms: "missing links" • whales • horse size

  4. Fossil Record • Find successive changes: "missing links" • whale legs & shape • horse size • hominid cranium

  5. Evidence for macroevolution • DNA: many genes are so similar that they must have diverged from a common ancestor: • Align genes, count diffs

  6. Evidence for macroevolution • DNA: many genes are so similar that they must have diverged from a common ancestor • Align genes, count diffs • # changes says when 2 spp. split

  7. Molecular clocks Align genes, count diffs # changes tells when 2 spp. split Calibrate with fossil record

  8. Mitochondrial DNA traces Mom • only comes from mom& doesn’t recombine • says we split ~ 170,000 years ago • Y chromosome • traces Dad • only comes from • dad & doesn’t • recombine • Says we entered • Europe ~ 50,000 • years ago

  9. Evidence for macroevolution Fossil record DNA Comparative anatomy: same bones derived from common ancestor: shape & function has changed

  10. Evidence for macroevolution • Fossil record • DNA • Comparative anatomy: same bones derived from common ancestor: shape & function changed • Vestigial structures: non-functional left-overs

  11. Evidence for macroevolution Fossils DNA Comparative anatomy Embryos retrace evolution as they develop

  12. Embryos retrace phylogeny Embryos retrace evolution as they develop

  13. Embryos retrace phylogeny Embryos retrace evolution as they develop Close spp look alike longer

  14. Convergent evolution similar selection results in organisms that look alike e.g. desert plants: American cacti & African euphorbs look alike but unrelated

  15. Convergent evolution similar selection -> organisms look alike e.g. Australian marsupials resemble American placental mammals

  16. Convergent evolution similar selection -> organisms look alike e.g. Australian marsupials resemble American placental Mammals Fill same niche: role in nature

  17. Analogy vs homology Analogous: look alike but different origin Bird vs insect wings

  18. Analogy vs homology Analogous: look alike but different origin Bird vs insect wings fins vs flippers

  19. Analogy vs homology • Analogous: look alike but diff origin • Bird vs insect wings • fins vs flippers • Homologous: look different, same origin

  20. Pace of evolution • Some plants evolve rapidly • Mammals evolve slowly • Starfish evolve very slowly

  21. Pace of evolution Gradualism: gradual evolution Large populations Slow change in selection

  22. Pace of evolution • Gradualism: gradual evolution • Large populations • Slow change in selection • Punctuated equilibria: evolve in spurts

  23. Pace of evolution Punctuated equilibria: evolve in spurts small populations Genetic drift alters gene pool Rapidly adapt then reach equilibrium

  24. Pace of evolution • Mass extinctions: • O2 poisoning 2 b.y.a. killed most bacteria

  25. Mass extinctions O2 poisoning 2 b.y.a. killed most bacteria 96% of species died at end of Permian Asteroid 65 m.y.a. killed dinosaurs

  26. Mass extinctions O2 poisoning 2 b.y.a. killed most bacteria 96% of species died at end of Permian: asteroid? Asteroid 65 m.y.a. killed dinosaurs Man is causing another mass extinction! Enable evolution of new spp!

  27. Mass extinctions Enable evolution of new spp! Formerly occupied niches become available major factor in success of mammals

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