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Chapter 14 – Principles of Evolution

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  1. Chapter 14 – Principles of Evolution • What is evolution? • Where did the concept of evolution come from? • How does evolution occur? • Why is the concept of evolution controversial to some people? • What does science know about the origin of life on Earth? • What does science know about the origin of humans? • What evidence exists of major evolutionary transitions? Chapter 14

  2. What is evolution? • A theory that explains the origin of life on Earth • A theory that explains why genetics of a population changes over time • A theory that explains how all life on Earth came about by changes from an original simple life form • All of these • None of these Chapter 14

  3. What is evolution? • Evolution – (a concept, a process, and a scientific fact) A change in the frequency of alleles in a population over time • The process by which characteristics of a population changes over time (p. 265) Chapter 14

  4. Are there changes in allele frequencies in populations over time? • Biological control of rabbits in Australia with Myxomatosis • 1952 – 99% mortality • Today – 40% mortality Chapter 14

  5. Science explains patterns in natural systems • What can explain why Myxomatosis mortality rates have decreased in the past 50 years? Evolution – a process by which the genetic characteristics of a population changes over time Chapter 14

  6. Did you know… • …the term “evolution” is conflated with other concepts? • The origin of the universe • The origin of the 1st life form • Common descent of species Chapter 14

  7. Evolution vs. Evolutionary theory • Evolutionary theories • Proposed mechanisms explaining why evolution occurs Chapter 14

  8. Where did the concept of evolution come from? • Early 1600’s – 3 fossil explanations • Inorganic • Noah’s flood • Evidence of a long history of life Chapter 14

  9. Did you know… • …in 1508, Leonardo Da Vinci rejected a global flood as an explanation of fossil deposition? Chapter 14

  10. Where did the concept of evolution come from? • William Smith (1769-1839) – Somerset Canal, index fossils & geological strata • 1815 – Fossil sorting inconsistent with flood scenario Chapter 14

  11. Chapter 14

  12. Patterns of life Chapter 14

  13. Locations where the entire geological column has been found intact Chapter 14

  14. Ediacaran/Vendian life (700-550 MYA) Chapter 14

  15. Vendian life Chapter 14

  16. Cambrian life (500MYA) – Burgess Shale Chapter 14

  17. Burgess Shale (British Columbia) Chapter 14

  18. Burgess Shale fossils • Aysheaia Chapter 14

  19. Burgess Shale fossils • Anomalocaris Chapter 14

  20. Burgess Shale fossils • Hallucogenia Chapter 14

  21. Burgess shale fossils • Ophabinia Chapter 14

  22. Burgess Shale fossils • Wiwaxia Chapter 14

  23. Did you know… • …life forms in the Pre-cambrian/ Cambrian age represent all known body plans (and all life was aquatic)? Chapter 14

  24. Did you know… • …the continents move? Chapter 14

  25. Seismologic patterns support plate tectonics Chapter 14

  26. Did you know… • …the distribution of fossils supports Pangaea Chapter 14

  27. Coprolite research Did you know… • …what dinosaurs ate? Chapter 14

  28. Did you know… …There are no fossilized flowering plants in older sedimentary rock? • x Chapter 14

  29. Where did the concept of evolution come from? • 1766 – Carolus Linnaeus – “Species are the work of time” • 1778 - Georges LeClerc proposed evolution, but no mechanism (theory) On modern species… “Conceived by Nature and produced by Time” Chapter 14

  30. Catastrophism vs. uniformitarianism • Georges Cuvier (1769-1832) • – Catastrophism • J. Hutton (1785) & C. Lyell (1830) – Uniformitarianism Chapter 14

  31. Glacial lake varves Ice core project Did you know… • …there are several independent methods that show the earth is very old? Chapter 14

  32. Where did the concept of evolution come from? • Jean Baptiste Lamarck, 1801 – Evolution by inheritance of acquired characteristics Chapter 14

  33. Where did the concept of evolution come from? • Charles Darwin &Alfred Wallace, 1858 – Evolution by the mechanism of natural selection Chapter 14

  34. Charles Darwin & natural selection Chapter 14

  35. Evolution occurs when… • A characteristic in a species is genetic • Genetic variation exists for the gene(s) involved in the characteristic • Selective pressure exists which confers a survival advantage to some individuals Chapter 14

  36. Science, Sept. 3, 2004 • Beak differences are genetic Chapter 14

  37. Evolution means… • The gene pool of a population (frequency of alleles) changes over time as a consequence of selective pressures • As the gene pool changes, so does the frequency of the characteristics influenced by the alleles selected for/against Chapter 14

  38. How does evolution occur? Figure 14-5 Chapter 14

  39. Does genetic variation exist within a species? Chapter 14

  40. Some genetic variation confers a survival advantage in a competitive environment Chapter 14

  41. Chapter 14

  42. Mutation is the source of genetic variation required for evolution Chapter 14

  43. Alleles conferring a survival advantage will be maintained in a population Sickle cell allelefrequency Chapter 14

  44. Sickle cell anemia • Those with 2 sickle cell alleles have a 1/5 chance of surviving to reproductive age • Those with 1 sickle cell allele have a 25% better chance of survival in a malaria environment Chapter 14

  45. Did you know… • …that change within an individual is not evolution? Chapter 14

  46. Natural selection and adaptation • 3 of 300 species of cichlid fishes in Lake Malawi (Africa) Chapter 14

  47. Asteracea – 23,000 species Chapter 14

  48. Naturally occurring pepper species Chapter 14

  49. Artificial selection and diversity Selection of genetic variation demonstrates the great range of differences that can occur Chapter 14

  50. Did you know… • …YECs call evolution “variation within kind”, and consider evolution to involve only large changes between different types of organisms? Chapter 14