1. AIM: What are the overall factors
causing evolution?
Warm-up:
Briefly describe 2 mechanisms that could
account for speciation.

2. 5 Agents of evolutionary change

3. 5 Agents of evolutionary change
Mutation

4. 5 Agents of evolutionary change
Mutation Gene Flow

5. 5 Agents of evolutionary change
Mutation Gene Flow Non-random mating

6. 5 Agents of evolutionary change
Mutation Gene Flow Non-random mating
Genetic Drift

7. 5 Agents of evolutionary change
Mutation Gene Flow Non-random mating
Genetic Drift Selection

8. 1. Mutation & Variation

9. 1. Mutation & Variation

10. 1. Mutation & Variation
§ Mutation creates variation

11. 1. Mutation & Variation
§ Mutation creates variation
u new mutations are constantly appearing

12. 1. Mutation & Variation
§ Mutation creates variation
u new mutations are constantly appearing
§ Mutation changes DNA sequence

13. 1. Mutation & Variation
§ Mutation creates variation
u new mutations are constantly appearing
§ Mutation changes DNA sequence
u changes amino acid sequence

14. 1. Mutation & Variation
§ Mutation creates variation
u new mutations are constantly appearing
§ Mutation changes DNA sequence
u changes amino acid sequence
u changes protein

15. 1. Mutation & Variation
§ Mutation creates variation
u new mutations are constantly appearing
§ Mutation changes DNA sequence
u changes amino acid sequence
u changes protein
u changes in protein may
change phenotype &
therefore change fitness

16. 2. Gene Flow

17. 2. Gene Flow

18. 2. Gene Flow
§ Movement of individuals &
alleles in & out of populations

19. 2. Gene Flow
§ Movement of individuals &
alleles in & out of populations
u seed & pollen distribution by
wind & insect

20. 2. Gene Flow
§ Movement of individuals &
alleles in & out of populations
u seed & pollen distribution by
wind & insect
u migration of animals

21. 2. Gene Flow
§ Movement of individuals &
alleles in & out of populations
u seed & pollen distribution by
wind & insect
u migration of animals
§ sub-populations may have
different allele frequencies

22. 2. Gene Flow
§ Movement of individuals &
alleles in & out of populations
u seed & pollen distribution by
wind & insect
u migration of animals
§ sub-populations may have
different allele frequencies
§ causes genetic mixing
across regions

23. 2. Gene Flow
§ Movement of individuals &
alleles in & out of populations
u seed & pollen distribution by
wind & insect
u migration of animals
§ sub-populations may have
different allele frequencies
§ causes genetic mixing
across regions
§ reduce differences
between populations

24. Human evolution today
§ Gene flow in human
populations is
increasing today
u transferring alleles
between populations

25. Human evolution today
§ Gene flow in human
populations is
increasing today
u transferring alleles
between populations

26. Human evolution today
§ Gene flow in human
populations is
increasing today
u transferring alleles
between populations
Are we moving towards a blended world?

27. 3. Non-random mating
§ Sexual selection

28. 3. Non-random mating
§ Sexual selection

29. 4. Genetic drift

30. 4. Genetic drift

31. 4. Genetic drift
§ Effect of chance events

32. 4. Genetic drift
§ Effect of chance events
u founder effect

33. 4. Genetic drift
§ Effect of chance events
u founder effect
§ small group splinters off & starts a new colony

34. 4. Genetic drift
§ Effect of chance events
u founder effect
§ small group splinters off & starts a new colony
er
Warbl
finc h
Gr
s
he
ou
inc
n d
ef
fin
e
ch
Tr
es

35. 4. Genetic drift
§ Effect of chance events
u founder effect
§ small group splinters off & starts a new colony
u bottleneck
er
Warbl
finc h
Gr
s
he
ou
inc
n d
ef
fin
e
ch
Tr
es

36. 4. Genetic drift
§ Effect of chance events
u founder effect
§ small group splinters off & starts a new colony
u bottleneck
§ some factor (disaster) reduces population to
small number & then population recovers &
expands again
er
Warbl
finc h
Gr
s
he
ou
inc
n d
ef
fin
e
ch
Tr
es

37. 4. Genetic drift
§ Effect of chance events
u founder effect
§ small group splinters off & starts a new colony
u bottleneck
§ some factor (disaster) reduces population to
small number & then population recovers &
expands again
er
Warbl
finc h
Gr
s
he
ou
inc
n d
ef
fin
e
ch
Tr
es

38. Founder effect

39. Founder effect
§ When a new population is started
by only a few individuals
u some rare alleles may be at high
frequency; others may
be missing
u skew the gene pool of
new population
§ human populations that
started from small group
of colonists
§ example:
colonization of New World

40. Distribution of blood types
§ Distribution of the O type blood allele in native
populations of the world reflects original settlement

41. Distribution of blood types
§ Distribution of the O type blood allele in native
populations of the world reflects original settlement

42. Distribution of blood types
§ Distribution of the O type blood allele in native
populations of the world reflects original settlement

43. Distribution of blood types
§ Distribution of the B type blood allele in native
populations of the world reflects original migration

44. Distribution of blood types
§ Distribution of the B type blood allele in native
populations of the world reflects original migration

45. Distribution of blood types
§ Distribution of the B type blood allele in native
populations of the world reflects original migration

46. Distribution of blood types
§ Distribution of the B type blood allele in native
populations of the world reflects original migration

47. Bottleneck effect

48. Bottleneck effect
§ When large population is drastically
reduced by a disaster

49. Bottleneck effect
§ When large population is drastically
reduced by a disaster
u famine, natural disaster, loss of habitat…

50. Bottleneck effect
§ When large population is drastically
reduced by a disaster
u famine, natural disaster, loss of habitat…
u loss of variation by chance event

51. Bottleneck effect
§ When large population is drastically
reduced by a disaster
u famine, natural disaster, loss of habitat…
u loss of variation by chance event
§ alleles lost from gene pool

52. Bottleneck effect
§ When large population is drastically
reduced by a disaster
u famine, natural disaster, loss of habitat…
u loss of variation by chance event
§ alleles lost from gene pool
w not due to fitness

53. Bottleneck effect
§ When large population is drastically
reduced by a disaster
u famine, natural disaster, loss of habitat…
u loss of variation by chance event
§ alleles lost from gene pool
w not due to fitness
§ narrows the gene pool

54. Cheetahs

55. Cheetahs
§ All cheetahs share a small number of alleles

56. Cheetahs
§ All cheetahs share a small number of alleles
u less than 1% diversity

57. Cheetahs
§ All cheetahs share a small number of alleles
u less than 1% diversity
u as if all cheetahs are
identical twins

58. Cheetahs
§ All cheetahs share a small number of alleles
u less than 1% diversity
u as if all cheetahs are
identical twins
§ 2 bottlenecks

59. Cheetahs
§ All cheetahs share a small number of alleles
u less than 1% diversity
u as if all cheetahs are
identical twins
§ 2 bottlenecks
u 10,000 years ago

60. Cheetahs
§ All cheetahs share a small number of alleles
u less than 1% diversity
u as if all cheetahs are
identical twins
§ 2 bottlenecks
u 10,000 years ago
§ Ice Age

61. Cheetahs
§ All cheetahs share a small number of alleles
u less than 1% diversity
u as if all cheetahs are
identical twins
§ 2 bottlenecks
u 10,000 years ago
§ Ice Age
u last 100 years

62. Cheetahs
§ All cheetahs share a small number of alleles
u less than 1% diversity
u as if all cheetahs are
identical twins
§ 2 bottlenecks
u 10,000 years ago
§ Ice Age
u last 100 years
§ poaching & loss of habitat

63. Peregrine Falcon
Conservation issues
Golden Lion
Tamarin

64. Peregrine Falcon
Conservation issues
§ Bottlenecking is an important
concept in conservation
biology of endangered
species
Golden Lion
Tamarin

65. Peregrine Falcon
Conservation issues
§ Bottlenecking is an important
concept in conservation
biology of endangered
species
u loss of alleles from gene pool
Golden Lion
Tamarin

66. Peregrine Falcon
Conservation issues
§ Bottlenecking is an important
concept in conservation
biology of endangered
species
u loss of alleles from gene pool
u reduces variation
Golden Lion
Tamarin

67. Peregrine Falcon
Conservation issues
§ Bottlenecking is an important
concept in conservation
biology of endangered
species
u loss of alleles from gene pool
u reduces variation
u reduces adaptability
Breeding programs must
consciously outcross Golden Lion
Tamarin

68. 5. Natural selection

69. 5. Natural selection
§ Differential survival & reproduction due
to changing environmental conditions

70. 5. Natural selection
§ Differential survival & reproduction due
to changing environmental conditions
§ climate change

71. 5. Natural selection
§ Differential survival & reproduction due
to changing environmental conditions
§ climate change
§ food source availability

72. 5. Natural selection
§ Differential survival & reproduction due
to changing environmental conditions
§ climate change
§ food source availability
§ predators, parasites, diseases

73. 5. Natural selection
§ Differential survival & reproduction due
to changing environmental conditions
§ climate change
§ food source availability
§ predators, parasites, diseases
§ toxins

74. 5. Natural selection
§ Differential survival & reproduction due
to changing environmental conditions
§ climate change
§ food source availability
§ predators, parasites, diseases
§ toxins
u combinations of alleles
that provide “fitness”
increase in the population

75. 5. Natural selection
§ Differential survival & reproduction due
to changing environmental conditions
§ climate change
§ food source availability
§ predators, parasites, diseases
§ toxins
u combinations of alleles
that provide “fitness”
increase in the population
§ adaptive evolutionary change