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Module 1: Evolution

Module 1: Evolution. Macroevolution. Microevolution. Change in the frequencies of genotypes in a population. The formation of new species. Species A. Species B. Time. Species A. Species B. Species A. Species A. Species B. Species C. Time. A species is.

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Module 1: Evolution

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  1. Module 1: Evolution

  2. Macroevolution Microevolution Change in the frequencies of genotypes in a population The formation of new species

  3. Species A Species B Time

  4. Species A Species B Species A Species A Species B Species C Time

  5. A species is... a group of actually or potentially interbreeding natural populations that are reproductively isolated from other such groups.

  6. A species is... a group of actually or potentially interbreeding natural populations that are reproductively isolated from other such groups.

  7. A species is... a group of actually or potentially interbreeding natural populations that are reproductively isolated from other such groups.

  8. A species is... a group of actually or potentially interbreeding natural populations that are reproductively isolated from other such groups.

  9. But what about asexual organisms?

  10. How do new species form? When gene flow ends between natural populations and their gene pool changes

  11. Once a barrier to gene flow is established... populations diverge because of microevolution

  12. How do new species form? • Allopatric speciation • Sympatric speciation • Parapatric speciation

  13. 1. Allopatric speciation • Literally “other country”

  14. 1. Allopatric speciation • Literally “other country” • Geographic barrier divides population or Part of population crosses barrier and “founds” new population

  15. 1. Allopatric speciation • Literally “other country” • Geographic barrier divides population or Part of population crosses barrier and “founds” new population • Most prevalent form of speciation

  16. Allopatric speciation • Geographic barrier divides population • Gene flow is cut off • Microevolution takes over • Populations differentiate

  17. Fig. 19-1, p.300

  18. Housefinch (Carpodacus) Fig. 19-7d13, p.305

  19. Iiwi (Vestiaria coccinea) Fig. 19-7d12, p.305

  20. 2. Sympatric speciation • Literally “same country”

  21. 2. Sympatric speciation • Literally “same country” • Species arise from a connected population

  22. 2. Sympatric speciation • Literally “same country” • Species arise from a connected population • Most common in plants

  23. 2. Sympatric speciation • Literally “same country” • Species arise from a connected population • Most common in plants • Occasionally seen in animals

  24. Speciation by polyploidy (plants) • Mistake during cell division

  25. Speciation by polyploidy (plants) • Mistake during cell division • New individual is viable but genetically isolated

  26. Speciation by polyploidy (plants) • Mistake during cell division • New individual is viable but genetically isolated • In plants, individual with new ploidy-level can often self-fertilize

  27. T. aestivum (one of the common bread wheats) Triticum monococcum (einkorn) T. tauschii (a wild relative) Unknown species of wild wheat T. turgidum (wild emmer) 14AA X 14BB 14AB 28AABB X 14DD 42AABBDD cross-fertilization, followed by a spontaneous chromosome doubling Speciation by polyploidy

  28. Speciation by behavioral change (animals) • Parents make “mistake”

  29. Speciation by behavioral change (animals) • Parents make “mistake” • Young pattern on a new place

  30. Speciation by behavioral change (animals) • Parents make “mistake” • Young pattern on a new place • Young return to place to mate

  31. Speciation by behavioral change (animals) • Parents make “mistake” • Young pattern on a new place • Young return to place to mate • No gene flow with original population

  32. 3. Parapatric speciation • Like allopatric speciation, except boundary is not physical

  33. 3. Parapatric speciation • Like allopatric speciation, except boundary is not physical • Parts of a population experience different conditions

  34. 3. Parapatric speciation • Like allopatric speciation, except boundary is not physical • Parts of a population experience different conditions • Natural selection is stronger than gene flow

  35. Bullock’s oriole Baltimore oriole hybrid zone Parapatric speciation

  36. Can species interbreed if they get back together?

  37. Species of European and American sycamores have been separated for 20 million years, yet they can still interbreed

  38. Reproductive barriers between species • Prezygotic barriers • barriers that prevent mating

  39. Reproductive barriers between species • Prezygotic barriers • barriers that prevent mating • Postzygotic barriers • Barriers that operate after mating occurs

  40. Prezygotic barriers • Behaviorial isolation • Ecological isolation • Temporal isolation • Mechanical isolation • Gametic isolation

  41. Fig. 19-4c, p.302

  42. Fig. 19-4d, p.302

  43. Fig. 19-4e, p.302

  44. Fig. 19-4b, p.302

  45. Fig. 19-4a, p.302

  46. Fig. 18-20, p.299

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