BIOL 108 Chp 10 pt 2

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BIOL 108 Chp 10 pt 2

  1. 1. Chapter 10 pt 2 The Origin and Diversification of Life on Earth BIOL 108 Intro to Bio Sci Rob Swatski Assoc Prof Biology HACC-York 1
  2. 2. 10.9 Similar structures don’t always reveal common ancestry. 2
  3. 3. 3
  4. 4. The mapping of species’ characteristics onto phylogenetic trees  Physical features  DNA sequences 4
  5. 5. 5
  6. 6. Convergent Evolution  and analogous traits 6
  7. 7. Analogous traits: Features that are produced by convergent evolution Homologous traits: Features that are inherited from a common ancestor 7
  8. 8. How do you know whether traits are homologous or analogous? DNA analysis 8
  9. 9. Which structures below are homologous? 1. 2. 3. 4. Human forearm and a monkey’s forearm Fish fin and whale fin Butterfly wing and bat wing All of the above 9
  10. 10. Take-Home Message 10.9 Evolutionary trees are best constructed by comparing genetic similarity among organisms. Convergent evolution can cause distantly related organisms to appear much more closely related. 10
  11. 11. 11
  12. 12. 10.10 Macroevolution is evolution above the species level. 12
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  15. 15. Take-Home Message 10.10 The process of evolution in conjunction with reproductive isolation… …is sufficient to produce speciation, diversification, and the rich diversity of life on earth. 15
  16. 16. 10.11 The pace of evolution is not constant. 16
  17. 17. 17
  18. 18. Take-Home Message 10.11 The pace at which evolution occurs can be rapid or very slow. In some cases, the fossil record reveals rapid periods of evolutionary change punctuated by longer periods with little change. In others cases, species may change at a more gradual, but consistent, pace. 18
  19. 19. 10.12 Adaptive radiations are times of extreme diversification. When a small number of species diversifies into a much larger number of species 19
  20. 20. 20
  21. 21.  Colonizers find a large number of opportunities for adaptation and diversification.  Galapagos finches  Hawaiian fruit flies 21
  22. 22.  innovations such as the wings and rigid skeleton that appeared in insects  helped them to diversify into the most successful group of animals  more than 800,000 species today! 22
  23. 23. The ability of multiple species to evolve via adaptive radiations is due to _______ over time. 1. 2. 3. 4. Macroevolution Microevolution Punctuated equilibrium Gradual change 23
  24. 24. Take-Home Message 10.12 Adaptive radiations tend to be triggered by: 1) mass extinctions of potentially competing species 2) colonization of new habitats 3) the appearance of evolutionary innovations 24
  25. 25. 10.13 There have been several mass extinctions on earth. 25
  26. 26. 26
  27. 27. Background Extinction  extinctions that occur at lower rates during periods other than periods of mass extinctions  occur mostly as the result of natural selection 27
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  29. 29. Background and Mass Extinctions Have Different Causes  Mass extinctions are due to extraordinary and sudden changes to the environment.  Background extinctions occur mostly as the result of natural selection. 29
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  31. 31. Take-Home Message 10.13 As new species are being created, others are lost through extinction. Extinction may be a consequence of natural selection or large, sudden changes in the environment. Mass extinctions are periods during which a large number of species on earth become extinct over a short period of time. These periods are usually followed by periods of unusually rapid adaptive radiations and diversification of the remaining species. 31
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  33. 33. 10.14 All living organisms are divided into one of three groups. 33
  34. 34. Classification Systems  The two-kingdom system • Animal and plant  The five-kingdom system • Monera, plant, animal, fungi, and protists 34
  35. 35. Classification Takes a Leap Forward  Carl Woese, an American biologist, and his colleagues  Examined  Tracking nucleotide sequences changes 35
  36. 36. 36
  37. 37. Woese’s approach is not perfect. Are viruses alive? 37
  38. 38. 38
  39. 39. Take-Home Message 10.14 All life on earth can be divided into three domains—bacteria, archaea, and eukarya—which reflect their evolutionary relatedness to each other. Plants and animals are just two of the four kingdoms in the eukarya domain, encompassing only a small fraction of the domain’s diversity. 39
  40. 40. 10.15 The bacteria domain has tremendous biological diversity. 40
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  42. 42. Bacteria Are a Monophyletic Group All bacteria have a few features in common:  single-celled organisms with no nucleus or organelles  one or more circular molecules of DNA  several methods of exchanging genetic information  asexual organisms 42
  43. 43. Which single-celled organism below is considered to be most closely related to the first cell to exist on our planet? 1. 2. 3. 4. 5. 6. Plants Protists Bacteria Archeae Animals Fungi 43
  44. 44. Take-Home Message 10.15 Bacteria have evolved a broad diversity of metabolic and reproductive abilities relative to Eukarya. The bacteria all share a common ancestor and have a few features in common: • All are prokaryotic, asexual, single-celled organisms with no nucleus or organelles. • All have one or more circular molecules of DNA as their genetic material. • All have several methods of exchanging genetic information. 44
  45. 45. 10.16 The archaea domain includes many species living in extreme environments. 45
  46. 46. 46
  47. 47. Several Physical Features Distinguish Archeans from the Bacteria  Archaeans’ cell walls contain polysaccharides not found in either bacteria or eukaryotes.  Archeans have cell membranes, ribosomes, and some enzymes similar to those found in eukaryotes. 47
  48. 48. Take-Home Message 10.16 Archaea, many of which are adapted to life in extreme environments, physically resemble bacteria but are more closely related to eukarya. Because they thrive in many habitats that humans have not yet studied well, including the deepest seas and oceans, they may turn out to be much more common than currently believed. 48
  49. 49. 10.17 The eukarya domain consists of four kingdoms. Plants, Animals, Fungi, and Protists 49
  50. 50. 50
  51. 51. Take-Home Message 10.17 All living organisms that you can see with the naked eye are eukarya, including all plants, animals, fungi, and protists. The eukarya are unique among the three domains in that they have cells with organelles. 51
  52. 52. Humans can be classified as… 1. 2. 3. 4. 5. Homo sapiens Eukarya Animals Vertebrates All of the above 52

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