1. Copyright © 2008 Pearson Education Inc., publishing as Pearson Benjamin Cummings The TLCC Has Free Tutoring Not happy with your grade? Need help understanding the material?

2. Copyright © 2008 Pearson Education, Inc., publishing as Pearson Benjamin Cummings PowerPoint ® Lecture Presentations for Biology Eighth Edition Neil Campbell and Jane Reece Lectures by Chris Romero, updated by Erin Barley with contributions from Joan Sharp Chapter 22 Descent with Modification: A Darwinian View of Life

3. Copyright © 2008 Pearson Education Inc., publishing as Pearson Benjamin Cummings Overview: Endless Forms Most Beautiful Charles Darwin changed biology when he published The Origin of Species in 1859 – Fringe idea  mainstream acceptance How? Decades of evidence – People had talked before about new species forming. Darwin had a method and years of observations to support it.

4. Copyright © 2008 Pearson Education Inc., publishing as Pearson Benjamin Cummings The “Somebody would have figured it out” principle

5. Copyright © 2008 Pearson Education Inc., publishing as Pearson Benjamin Cummings Darwin noted that current species are descendants of ancestral species Evolution can be defined by Darwin’s phrase descent with modification Evolution can be viewed as both a pattern and a process I know nothing about this bug 

6. Copyright © 2008 Pearson Education Inc., publishing as Pearson Benjamin Cummings Difference? He said how, and had evidence that difference changed everything Concept 22.1: Darwin built on earlier ideas of intellectuals

7. Copyright © 2008 Pearson Education Inc., publishing as Pearson Benjamin Cummings Scala Naturae and Classification of Species Aristotle: arranged species on scala naturae (natural scale) – Thought species never changed Linnaeus: taxonomy (classifying organisms) Each species created individually for a specific purpose

8. Copyright © 2008 Pearson Education Inc., publishing as Pearson Benjamin Cummings Fossils: life now different from life in past Fossils: remains or traces of past organisms Found in strata (layers) The study of fossils helped to lay the groundwork for Darwin’s ideas

9. Copyright © 2008 Pearson Education Inc., publishing as Pearson Benjamin Cummings Paleontology: the study of fossils Georges Cuvier advocated catastrophism – The idea strata boundaries are formed by catastrophies

10. Copyright © 2008 Pearson Education Inc., publishing as Pearson Benjamin Cummings James Hutton and Charles Lyell: earth shaped by slow gradual processes – Uniformitarianism: the mechanisms of change are constant over time Lyell’s book Principles of Geology strongly influenced Darwin’s thinking If the processes are slow, the earth must be old Lyell’s book convinced many scientists, not just Darwin

11. Copyright © 2008 Pearson Education Inc., publishing as Pearson Benjamin Cummings Lamarck: Evolution due to use and disuse Lamarck: evolution = use, disuse, and inheritance of acquired characteristics Not much evidence for this method (we think lamarck was wrong) The book says “no” evidence

12. Copyright © 2008 Pearson Education Inc., publishing as Pearson Benjamin Cummings Early 1800’s: most people still thought species never changed However, a few scientists were beginning to discuss the idea of new species forming Concept 22.2: Descent with modification by natural selection

13. Copyright © 2008 Pearson Education Inc., publishing as Pearson Benjamin Cummings Darwin: liked to study nature (child  adult) Darwin studied @ Cambridge University: – started in medicine – switched to theology Graduated took position on the Beagle as a naturalist, around the world,1831-1836

14. Copyright © 2008 Pearson Education Inc., publishing as Pearson Benjamin Cummings The Voyage of the Beagle: what did darwin do? Collected South American plants and animals – Saw adaptations to many diverse environments He read a lot – Lyell’s Principles of Geology: earth > 6000 years old – Malthus: people compete, some win, some loose

15. Copyright © 2008 Pearson Education Inc., publishing as Pearson Benjamin Cummings Galápagos Islands: many unique species He saw that these species had features that seem to be useful in their environment and their lifestyle Darwin explained this as adaptation due to “Natural Selection”

16. Fig. 22-6 (a) Cactus-eater(c) Seed-eater (b) Insect-eater

17. Vampire Finch!!!! OK, it’s really called the “Sharp beaked ground finch”

18. Copyright © 2008 Pearson Education Inc., publishing as Pearson Benjamin Cummings 1836: the Beagle trip ends 1844: Darwin writes essay on species’ origin and natural selection – won’t publish or discuss publicly (probably wanted more evidence: fringe  mainstream) Discussed privately with other scientists Showed essay to Joseph Hooker in 1847 Wrote a letter to Asa Grey about it in 1857 Wrote to Alfred Russell Wallace about it in 1857 Two times Darwin had the idea, but would not publish

19. Copyright © 2008 Pearson Education Inc., publishing as Pearson Benjamin Cummings So what was Darwin doing from 1836 until 1859? 1.Writing books on books on coral reefs, barnacles, geology became a famous scientist for this 2.Collects info and writes notes Gathering evidence for natural selection. (plans to publish someday) Darwin had the idea, but would not publish

20. Copyright © 2008 Pearson Education Inc., publishing as Pearson Benjamin Cummings 1855: Wallace sent essay to Darwin "On the Law which has regulated the Introduction of New Species“ Darwin wrote back saying that they were thinking similarly, and that he’d have a publication on the same topic within a few years Alfred Russell Wallace finds same thing

21. Copyright © 2008 Pearson Education Inc., publishing as Pearson Benjamin Cummings 1857: Wallace sent another essay to Darwin “On the Tendency of Varieties to Depart Indefinitely From the Original Type” Same idea’s as Darwin’s “Natural Selection” but didn’t use that term Darwin quickly finished The Origin of Species and published it the next year – Didn’t want to get scooped Alfred Russell Wallace and natural selection

22. Copyright © 2008 Pearson Education Inc., publishing as Pearson Benjamin Cummings June 1858: Darwin gets this second paper on speciation from Alfred Russell Wallace Wallace asks Darwin to review, give to Lyell Darwin tells Lyell and Hooker that it is basically the same as what he was going to write Lyell, Hooker and Darwin present Wallace’s paper at meeting of scientific society (along with letters showing Darwin had the same idea earlier) Alfred Russell Wallace had the same idea

23. Copyright © 2008 Pearson Education Inc., publishing as Pearson Benjamin Cummings Wallace wrote a paper. Darwin wrote a book. 1859: Darwin publishes Origin of the Species What: species are different now than past How: same method as selective breeding Evidence: 20+ years of observations Why do we talk about Darwin, not Wallace?

24. Copyright © 2008 Pearson Education Inc., publishing as Pearson Benjamin Cummings It may look like it now, but probably not Famous naturalist: already had good reputation Wallace was an unknown Wealthy, respected family Wallace: a lot less money (less likely to be listened to in Victorian England) Could easily have taken all the credit Later helped Wallace find a job Was Darwin a Jerk? Probably not

25. Copyright © 2008 Pearson Education Inc., publishing as Pearson Benjamin Cummings The Origin of Species (1859) Darwin developed two main ideas: 1.“Descent with modification” explains life’s unity and diversity – What we now call “evolution” – He didn’t use that term when writing book 2.Natural selection is a cause of adaptive evolution

26. Copyright © 2008 Pearson Education Inc., publishing as Pearson Benjamin Cummings Descent with Modification The phrase ”descent with modification” organisms are related: common ancestor in past Old, but uncommon, idea Zoonomia, Erasmus Darwin C. Darwin explained HOW, had EVIDENCE

27. Copyright © 2008 Pearson Education Inc., publishing as Pearson Benjamin Cummings the history of life is like a tree with branches representing life’s diversity Darwin’s theory can explain hierarchy of Linnaeus Darwinian view of natural world

28. Copyright © 2008 Pearson Education Inc., publishing as Pearson Benjamin Cummings Darwin: Natural Selection is like Artificial Selection artificial selection: humans modify by selecting and breeding individuals with desired traits

29. Copyright © 2008 Pearson Education Inc., publishing as Pearson Benjamin Cummings Darwin: Natural Selection is like Artificial Selection Darwin then described four observations 1.Variation exists 2.Traits can be inherited from parents 3.Too many offspring for environment 4.Competition to survive, not all will Darwin made two inferences Will discuss in a second

30. Copyright © 2008 Pearson Education Inc., publishing as Pearson Benjamin Cummings Observation #1: Members of a population often vary greatly in their traits

31. If all the spores grew up we’d live in mushroom world Observation #2: Traits are inherited from parents to offspring Observation #3: All species are capable of producing more offspring than the environment can support

32. Copyright © 2008 Pearson Education Inc., publishing as Pearson Benjamin Cummings Observation #4: Owing to lack of food or other resources, many of these offspring do not survive We don’t live in mushroom world!!!! Most spores die 

33. Copyright © 2008 Pearson Education Inc., publishing as Pearson Benjamin Cummings Inference #1: Individuals whose inherited traits give them a higher probability of surviving and reproducing in a given environment tend to leave more offspring than other individuals The ones that survive get to make babies!!! Darwin’s two inferences

34. Copyright © 2008 Pearson Education Inc., publishing as Pearson Benjamin Cummings Inference #2: This unequal ability of individuals to survive and reproduce will lead to the accumulation of favorable traits in the population over generations The ones with good traits live to breed, so good traits accumulate Darwin’s two inferences

35. Copyright © 2008 Pearson Education Inc., publishing as Pearson Benjamin Cummings Thomas Malthus: humans might reproduce so fast that they run out of food and resources Good traits accumulate, and individuals with good traits are will become more common This process explains the match between organisms and their environment Wallace also based his ideas on Malthus!!! Darwin applied Malthus to nature

36. Fig. 22-12 (b) A stick mantid in Africa (a) A flower mantid in Malaysia the match between organisms and their environment

37. Copyright © 2008 Pearson Education Inc., publishing as Pearson Benjamin Cummings Natural Selection: A Summary Good traits = survival = live to breed – # of kids: how evolution keeps score Good traits build up, and organisms appear to adapt to their environment – Populations evolve, not individuals!!!!! natural selection + new environmental conditions can cause new species to form

38. Copyright © 2008 Pearson Education Inc., publishing as Pearson Benjamin Cummings Note that individuals do not evolve; populations evolve over time Evolution: A change in the genetic makeup of a population over time Natural selection can only increase or decrease heritable traits in a population – Works on existing traits. – Mutation, not natural selection, makes new traits Adaptations vary with different environments

39. Copyright © 2008 Pearson Education Inc., publishing as Pearson Benjamin Cummings Lamarck vs. Darwin/Wallace Thought individuals evolved   populations evolve because those bad traits don’t have kids

40. Copyright © 2008 Pearson Education Inc., publishing as Pearson Benjamin Cummings Concept 22.3: Evolution has LOTS of evidence New discoveries continue add more evidence – Guppies – Drug resistant HIV

41. Copyright © 2008 Pearson Education Inc., publishing as Pearson Benjamin Cummings Predation and Coloration in Guppies : Scientific Inquiry John Endler has studied the effects of predators on wild guppy populations Brightly colored males are more attractive to females However, brightly colored males are more vulnerable to predation Guppy populations in pools with fewer predators had more brightly colored males What happens to a group if you move them?

42. Copyright © 2008 Pearson Education Inc., publishing as Pearson Benjamin Cummings Endler put drab colored guppies (many predators) in a pool with few predators As predicted, the population changed dull  bright Results match prediction: support for evolution More bright spots More area Covered in Bright spots

43. Copyright © 2008 Pearson Education Inc., publishing as Pearson Benjamin Cummings Endler transferred brightly colored guppies (with few predators) to a pool with many predators As predicted, over time the population became less brightly colored Results match prediction: support for evolution 

44. Copyright © 2008 Pearson Education Inc., publishing as Pearson Benjamin Cummings Direct Observations of Evolutionary Change the evolution of drug-resistant HIV drugs to fight HIV selects for viruses resistant to these drugs The drug 3TC is supposed to interfere with HIV’s reverse transcriptase enzyme Virus needs enzyme for RNA  DNA

45. Copyright © 2008 Pearson Education Inc., publishing as Pearson Benjamin Cummings The Evolution of Drug-Resistant HIV there are different forms of Reverse Transcriptase Some variations are immune to 3TC Can make DNA without errors Viruses with 3TC resistant enzymes are better are reproducing, and become more common than other variants Now HIV strains have resistance to 3TC The ability of bacteria and viruses to evolve rapidly poses a challenge to our society

46. Fig. 22-14 Weeks Patient No. 3 Patient No. 2 Patient No. 1 Percent of HIV resistant to 3TC 0 0 25 50 75 100 2 4681012

47. Copyright © 2008 Pearson Education Inc., publishing as Pearson Benjamin Cummings Natural selection does not create new traits It chooses between existing traits in the phenotype local environment determines what is selected for or against Natural Selection: like pruning shears

48. Copyright © 2008 Pearson Education Inc., publishing as Pearson Benjamin Cummings The Fossil Record – records of past living things Extinctions New groups Changes in groups

49. Copyright © 2008 Pearson Education Inc., publishing as Pearson Benjamin Cummings Archeopteryx Lizard and bird features Transitional Fossils Exist

50. Copyright © 2008 Pearson Education Inc., publishing as Pearson Benjamin Cummings 11 specimens found, various sizes Transitional Fossils Exist

51. Copyright © 2008 Pearson Education Inc., publishing as Pearson Benjamin Cummings reconstructions Very lizard-like, very bird- like…the only sure thing is that they probably don’t look right

52. Copyright © 2008 Pearson Education Inc., publishing as Pearson Benjamin Cummings Archeopteryx is not the only one found Transitional Fossils: Changes in groups

53. Copyright © 2008 Pearson Education Inc., publishing as Pearson Benjamin Cummings Prediction: we should find intermediate or transitional fossils that show change Transitional Fossils: Changes in groups

54. Copyright © 2008 Pearson Education Inc., publishing as Pearson Benjamin Cummings Homology: similarity due to common ancestors Homologous structures are anatomical resemblances that represent variations on a structural theme present in a common ancestor

55. Copyright © 2008 Pearson Education Inc., publishing as Pearson Benjamin Cummings Comparative embryology reveals anatomical homologies not visible in adult organisms Homology in Embryos

56. Copyright © 2008 Pearson Education Inc., publishing as Pearson Benjamin Cummings Examples of homologies at the molecular level are genes shared among organisms inherited from a common ancestor Molecular Homology

57. Copyright © 2008 Pearson Education Inc., publishing as Pearson Benjamin Cummings Homologies and “Tree Thinking” The Darwinian concept of an evolutionary tree of life can explain homologies Evolutionary trees are hypotheses about the relationships among different groups Evolutionary trees can be made using different types of data, for example, anatomical and DNA sequence data

58. Fig. 22-19 Hawks and other birds Ostriches Crocodiles Lizards and snakes Amphibians Mammals Lungfishes Tetrapod limbs Amnion Feathers Homologous characteristic Branch point (common ancestor) Tetrapods Amniotes Birds 6 5 4 3 2 1

59. Copyright © 2008 Pearson Education Inc., publishing as Pearson Benjamin Cummings Vestigial structures have reduced function Python “spurs”, ING (19:39)spurs

60. Copyright © 2008 Pearson Education Inc., publishing as Pearson Benjamin Cummings Skinks – lizard with legs

61. Copyright © 2008 Pearson Education Inc., publishing as Pearson Benjamin Cummings Skinks – With Reduced Legs

62. Copyright © 2008 Pearson Education Inc., publishing as Pearson Benjamin Cummings Florida’s Glass lizards and Worm Lizards http://ufwildlife.ifas.ufl.edu/snakes/leglesslizards.shtml “We don’t need no stinkin’ legs”

63. Copyright © 2008 Pearson Education Inc., publishing as Pearson Benjamin Cummings Vestigial structures have reduced function Whale PelvisWhale Pelvis, ING (44:27)

64. Copyright © 2008 Pearson Education Inc., publishing as Pearson Benjamin Cummings Dorudon: intemediate limbs, joints + nostrils

65. Copyright © 2008 Pearson Education Inc., publishing as Pearson Benjamin Cummings Dorudon: Pelvis and legs

66. Copyright © 2008 Pearson Education Inc., publishing as Pearson Benjamin Cummings Dorudon: front flippers had elbows

67. Copyright © 2008 Pearson Education Inc., publishing as Pearson Benjamin Cummings Convergent Evolution: similar but NOT from ancestry Convergent evolution is the evolution of similar traits because of a similar lifestyle Analogous traits: similar features in distantly related organisms Convergent evolution does not provide information about ancestry

68. Fig. 22-20 Sugar glider Flying squirrel AUSTRALIA NORTH AMERICA

69. Copyright © 2008 Pearson Education Inc., publishing as Pearson Benjamin Cummings Biogeography: geographic distribution of species an important part of Charles Darwin’s theory of evolution Endemic species: particular to that location Islands have many endemic species  often closely related to species on the nearest mainland or island  Seen by Darwin in Galapagos  Seen by Wallace in Indonesia

70. Copyright © 2008 Pearson Education Inc., publishing as Pearson Benjamin Cummings Earth’s continents were formerly united in a single large continent called Pangaea, but have since separated by continental drift An understanding of continent movement and modern distribution of species allows us to predict when and where different groups evolved

71. Copyright © 2008 Pearson Education Inc., publishing as Pearson Benjamin Cummings Homology vs. Convergence: how to tell the difference What scientists think about the relationships between organisms can ALWAYS change No belief in biology is above challenge, and relationships are always being reexamined The only way to separate homology from convergence is to use EVERY method we can to examine both the similarities and differences Fossilsembryologymorphology DNAproteindistribution Math game: bias

72. Copyright © 2008 Pearson Education Inc., publishing as Pearson Benjamin Cummings You should now be able to: 1.Describe the contributions to evolutionary theory made by Linnaeus, Cuvier, Lyell, Lamarck, Malthus, and Wallace 2.Describe Lamarck’s theories, and explain why they have been rejected 3.Explain what Darwin meant by “descent with modification” 4.List and explain Darwin’s four observations and two inferences

73. Copyright © 2008 Pearson Education Inc., publishing as Pearson Benjamin Cummings 5.Explain why an individual organism cannot evolve 6.Describe at least four lines of evidence for evolution by natural selection

74. Copyright © 2008 Pearson Education Inc., publishing as Pearson Benjamin Cummings The TLCC Has Free Tutoring Not happy with your grade? Need help understanding the material?