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Introduction to Darwinian Evolution

Introduction to Darwinian Evolution. Chapter 18. Learning Objective 1. What is evolution ?. Evolution. Accumulation of inherited changes within a population over time Unifying concept of biology links all fields of life sciences into a unified body of knowledge. Learning Objective 2.

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Introduction to Darwinian Evolution

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  1. Introduction toDarwinian Evolution Chapter 18

  2. Learning Objective 1 • What is evolution?

  3. Evolution • Accumulation of inherited changes within a population over time • Unifying concept of biology • links all fields of life sciences into a unified body of knowledge

  4. Learning Objective 2 • Discuss the historical development of the theory of evolution

  5. Jean Baptiste de Lamarck • Proposed that organisms • change over time by natural phenomena, not divine intervention • had vital force that changed them toward greater complexity over time • could pass traits acquired during lifetime to offspring

  6. Charles Darwin • Theory of evolution • Based on observations during voyage of HMSBeagle • Found similarities between organisms • on arid Galápagos Islands • on humid South American mainland

  7. Voyage of HMS Beagle

  8. Darwin • Influenced by artificial selection • variety of domesticated plants and animals • Applied Thomas Malthus’s ideas • on human populations to natural populations • Influenced by geologists (Charles Lyell) • idea that Earth was extremely old

  9. Genetic Variation • Artificial selection • Natural Variation

  10. KEY CONCEPTS • Ideas about evolution originated long before Darwin’s time

  11. Learning Objective 3 • What are the four premises of evolution by natural selection as proposed by Charles Darwin?

  12. 4 Premises of Evolution by Natural Selection 1. Genetic variation • exists among individuals in population 2. Reproductive ability of each species • causes populations to geometrically increase over time

  13. 4 Premises of Evolution 3. Organisms compete with one another • for resources: food, living space, water, light 4. Offspring with most favorable characteristics • most likely to survive and reproduce • pass genetic characteristics to next generation

  14. Natural Selection • Results in adaptations • evolutionary modifications • improve chances of survival and reproductive success in a particular environment • Over time • accumulated changes in geographically separated populations produce new species

  15. KEY CONCEPTS • Darwin’s voyage on the Beagle provided the basis for his theory of evolution by natural selection

  16. Galapagos Finches

  17. Fig. 18-4a, p. 395

  18. Fig. 18-4b, p. 395

  19. Fig. 18-4c, p. 395

  20. Animation: The Galapagos Islands CLICKTO PLAY

  21. KEY CONCEPTS • Natural selection occurs because individuals with traits that make them better adapted to local conditions are more likely to survive and produce offspring than are individuals that are not as well adapted

  22. Learning Objective 4 • What is the difference between the modern synthesis and Darwin’s original theory of evolution?

  23. Modern Synthesis • Or synthetic theory of evolution • combines Darwin’s theory of evolution by natural selection with modern genetics • Explains • why individuals in a population vary • how species adapt to their environment

  24. Mutation • Provides genetic variability • that natural selection acts on during evolution

  25. KEY CONCEPTS • The modern synthesis combines Darwin’s theory with genetics

  26. Learning Objective 5 • What evidence for evolution can be obtained from the fossil record?

  27. Fossil Record • Fossils • remains or traces of ancient organisms • provide direct evidence of evolution

  28. Fossil Record • Sedimentary rock • layers occur in sequence of deposition • recent layers on top of older ones • Index fossils • characterize specific layer • Radioisotopes • in rock accurately measure rock’s age

  29. Sedimentary Rock

  30. Fossils

  31. Whale Evolution

  32. Mesonychid Fig. 18-8a, p. 399

  33. Ambulocetus natans Fig. 18-8b, p. 399

  34. Rodhocetus Fig. 18-8c, p. 399

  35. Basilosaurus Fig. 18-8d, p. 399

  36. Balaenoptera Fig. 18-8e, p. 399

  37. Radioisotope Decay

  38. Learning Objective 6 • What evidence for evolution is derived from comparative anatomy?

  39. Homologous Features • Basic structural similarities • structures may be used in different ways • Derived from same structure • in common ancestor • Indicate organism’s evolutionary affinities

  40. Homology in Animals

  41. HUMAN BAT WHALE CAT Humerus Radius Ulna Humerus Carpal Radius 5 Metacarpal Ulna Carpal 4 1 Radius Ulna 1 5 Carpal 1 Metacarpal 3 2 Phalanges 4 2 1 2 3 4 3 Phalanges 5 5 2 4 3 Fig. 18-10, p. 401

  42. Humerus Radius Ulna Humerus Carpal Radius 5 Metacarpal Ulna Carpal 4 1 Radius Ulna 1 5 Carpal 1 Metacarpal 3 2 Phalanges 4 2 1 2 3 4 3 Phalanges 5 5 2 4 3 HUMAN BAT WHALE CAT Stepped Art Fig. 18-10, p. 401

  43. Homology in Plants

  44. Spine Fig. 18-11a, p. 401

  45. Tendril Leaflet Leaf petiole Stipule Stem Fig. 18-11b, p. 401

  46. Homoplastic Features • Evolved independently • similar functions in distantly related organisms • Demonstrate convergent evolution • organisms with separate ancestries adapt similarly to comparable environments

  47. Aardvark (Orycteropus afer) Fig. 18-12a, p. 402

  48. Giant anteater (Myrmecophaga tridactyla) Fig. 18-12b, p. 402

  49. Pangolin (Manis crassicaudata) Fig. 18-12c, p. 402

  50. Homoplasy

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