1. Chapter 23 The Evolution of Populations

2. Question? u Is the unit of evolution the individual or the population?

3. So what do we study?

4. Population Genetics

5. Modern Synthesis

6. Population

7. Species

8. Gene Pool

9. Microevolution

10. Hardy-Weinberg Theorem

11. Basic Equation

12. Expanded Equation

13. Genotypes

14. Example Calculation u Let’s look at a population where: u A = red flowers u a = white flowers

16. Starting Population u N = 500 u Red = 480 (320 AA+ 160 Aa) u White = 20 u Total Genes = 2 x 500 = 1000

17. Dominant Allele u A = (320 x 2) + (160 x 1) = 800 = 800/1000 A = 80%

18. Recessive Allele u a = (160 x 1) + (20 x 2) = 200/1000 =.20 a = 20%

19. A and a in HW equation u Cross: Aa X Aa u Result = AA + 2Aa + aa u Remember: A = p, a = q

20. Substitute the values for A and a u p 2 + 2pq + q 2 = 1 (.8) 2 + 2(.8)(.2) + (.2) 2 = 1.64 +.32 +.04 = 1

21. Dominant Allele u A = p 2 + pq =.64 +.16 =.80 = 80%

22. Recessive Allele u a = pq + q 2 =.16 +.04 =.20 = 20%

23. Result

24. Importance of Hardy-Weinberg

25. Example

26. PKU Frequency

27. Dominant Allele

28. Expanded Equation

29. Final Results

30. Practice Problem u A fruit fly population has a gene with two alleles A1 & A2. 70% of the gametes produced in the population carry A1. What is the proportion of the population that are heterozygous?

31. Practice Problem u In a H-W population with two alleles, A & a, that are in equilibrium, the frequency of allele a is 0.7. What is the percentage of the population that is heterozygous for this allele?

32. AP Problems Using Hardy-Weinberg u Solve for q 2 (% of total). u Solve for q (equation). u Solve for p (1- q). u H-W is always on the national AP Bio exam (but no calculators are allowed).

33. Hardy-Weinberg Assumptions

34. If H-W assumptions hold true:

35. Microevolution

36. Causes of Microevolution

37. Genetic Drift

38. By Chance

39. Bottleneck Effect

41. Result

42. Importance

43. Founder's Effect

44. Result

45. Importance

46. Gene Flow

47. Result

48. Mutations

49. Result

50. Nonrandom Mating

51. Causes

52. Result

53. Natural Selection

54. Comment

55. Result

56. Genetic Basis of Variation

57. Polymorphism

58. Examples Garter Snakes Gaillardia

59. Human Example

60. Other examples

61. Quantitative Characters

62. Yarrow and Altitude

63. Sources of Genetic Variation

64. Preserving Genetic Variation

65. Example

66. Result

68. Comment

69. Fitness - Darwinian

70. Relative Fitness

71. Rate of Selection

72. Modes of Natural Selection

73. Stabilizing

74. Directional Selection

76. Diversifying

78. Comment

80. Sexual Mate selection

81. Result

82. Comments

83. Question u Does evolution result in perfect organisms?

84. Answer - No

85. Evolution is limited by historical constraints

86. Adaptations are often compromises.

87. Chance, Natural selection and the environment all interact

88. Selection can only act on existing variations

89. Summary u Know the difference between a species and a population. u Know that the unit of evolution is the population and not the individual.

90. Summary u Know the H-W equations and how to use them in calculations. u Know the H-W assumptions and what happens if each is violated.

91. Summary u Identify various means to introduce genetic variation into populations. u Know the various types of natural selection.