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Arguments & evidence

Arguments & evidence. How incredibly stupid not to have thought of that Thomas Huxley. Arguments. Blending inheritance Variability Isolation Age of the earth. Arguments. Blending inheritance -new adaptations diluted with each generation. Darwin’s reply:

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Arguments & evidence

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  1. Arguments & evidence

  2. How incredibly stupid not to have thought of that Thomas Huxley

  3. Arguments Blending inheritance Variability Isolation Age of the earth

  4. Arguments Blending inheritance -new adaptations diluted with each generation Darwin’s reply: Favorable traits maintained if popln isolated Some traits ‘preponent’ Adaptive traits arise often Enhanced reproduction of favorable traits

  5. Arguments Variability -Darwin confined natural selection to small, continuous variation How could new spp arise from small variations? -successive change through time How could small variations confer an advantage? -Darwin could not answer, later demonstrated How could selection act on a nonexistent trait? -preadaptation - new organ modified from another

  6. 1% per generation change in anatomy <500000 yrs

  7. Arguments Isolation -how could a new spp evolve in close proximity to its parents Darwin did not emphasize isolation as a primary cause for evolution

  8. Biblical 5,000 Newton 50,000 Buffon 75,000 Kelvin 100,000,000 present 4,500,000,000 Arguments Age of the earth -earth was not old enough to allow time for evolution

  9. Arguments Blending inheritance Variability Isolation Age of the earth

  10. Evidence Systematics Geographic distribution Comparative anatomy Embryology Fossils Artificial selection Direct observation

  11. Evidence Systematics -gradation of species easily understood by evolutionary relationships

  12. Evidence Geographic distribution -evolutionarily related organisms geographically connected

  13. Evidence Geographic distribution -evolutionarily related organisms geographically connected marsupial radiation

  14. Evidence Comparative anatomy homologous/analogous organs

  15. Evidence Comparative anatomy homologous/analogous organs Darwin’s interpretation of homology has become the definition: similarity due to common ancestry

  16. Evidence Comparative anatomy homologous/analogous organs

  17. Organisms show curious similarities in structure and development unrelated to function

  18. Evidence Comparative anatomy convergent evolution

  19. Evidence Comparative anatomy vestigial organs

  20. Evidence Comparative anatomy vestigial organs whale ancestor modern whale femur

  21. Organisms have vestigial structural, developmental and molecular traits Vestigial structures are a manifestation of change through time

  22. Evidence Embryology -remarkable similarity among diverse vertebrates

  23. Evidence Fossils -vast majority of fossil forms differ from extant spp extinction succession transitional forms environmental changes

  24. Evidence Fossils -vast majority of fossil forms differ from extant spp extinction The fact that many species have gone extinct suggests that Earth’s flora and fauna have changed over time

  25. Evidence Fossils -vast majority of fossil forms differ from extant spp transitional forms

  26. Evidence Fossils -vast majority of fossil forms differ from extant spp “living fossils”

  27. Evidence Fossils -vast majority of fossil forms differ from extant spp extinction succession transitional forms environmental changes

  28. Evidence Artificial selection -accelerated evolution based on human-favored traits

  29. Evidence Artificial selection -accelerated evolution based on human-favored traits

  30. Evidence Direct observation -natural selection can be observed in real time Observations on living organisms show that populations and species change over time

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