This document provides information about evolution including: - Natural selection causes evolution by favoring traits that increase survival and reproduction. - Domestic plants like cabbage, broccoli and kale evolved from a common wild ancestor through artificial selection on different traits. - There is direct evidence for evolution from observations of antibiotic resistant bacteria and other examples of adaptive evolution. - Classification systems reflect evolutionary relationships as organisms with shared ancestry have similar characteristics. - Homologous structures and vestigial traits provide evidence that organisms share a common ancestor. - Transition fossils provide evidence of gradual evolution from one form to another over generations.

2. In questions of science, the authority
of a thousand is not worth the sound
reasoning of a single individual.
- Galileo Galilei (1564-1642)

5. Propose hypotheses for how life
on Earth came to be the way it
is now

13. FACT Individuals within populations
vary.
FACT Some of the variation among
individuals is passed on to
offspring.
FACT Populations produce more
offspring than can survive.
FACT Survival and reproduction are not
random.
INFERENCE Natural selection
causes evolution.

16. Figure 22.9
Brussels
sprouts
Kale
Selection
for leaves
Selection for
axillary (side)
buds
Selection for
apical (tip) bud
Cabbage
Broccoli
KohlrabiWild mustard
Selection
for stems
Selection
for flowers
and stems

19. Evaluating the Evidence for
Evolution (by common descent)
• Direct observations
– Antibiotic resistant bacteria
– Drug resistant germs
– Insecticide resistant insects
– Herbicide resistant weeds
– Galapagos finch beaks
– Cichlid fish in Lake Victoria
– Many, many other examples

20. Evaluating the Evidence for
Evolution (by common descent)
• Direct observations
• Biological classification
– What explains why different organisms or
species share the same traits?
– Taxonomic groups are determined by shared
similar characteristics.

21. Evaluating the Evidence for
Evolution (by common descent)
• Direct observations
• Biological classification
• Homology in comparative anatomy

23. It is not the strongest of the
species that survive, nor the
most intelligent, but the one
most responsive to change.
- Charles Darwin

24. Convergent Evolution
Penguin
Dolphin

25. Flying squirrel Flying phalanger

26. Groundhog Wombat

27. Badger Tasmanian devil

28. Coyote Tasmanian tiger

29. American Cactus African Euphorbia

30. Coevolution

31. Evaluating the Evidence for
Evolution (by common descent)
• Direct observations
• Biological classification
• Homology in comparative anatomy
– Homologous structures
• Vertebrate limbs, vertebrae, skulls, exoskeletons
• Lab: Hominid skull comparisons
– Vestigial traits

32. Evaluating the Evidence for
Evolution (by common descent)
• Direct observations
• Biological classification
• Homology in comparative anatomy
– Homologous structures
– Vestigial structures
• Appendix, wisdom teeth, human body hair, snake
“claws”, whale leg bones, micropterous insects

34. Evaluating the Evidence for
Evolution (by common descent)
• Direct observations
• Biological classification
• Homology in comparative anatomy
• Homology in development

38. Evaluating the Evidence for
Evolution (by common descent)
• Direct observations
• Biological classification
• Homology in comparative anatomy
• Homology in development
• Homology in biochemistry
– The more similar DNA, proteins, and other
biochemistry is, the more closely related
organisms are.

40. Evaluating the Evidence for
Evolution (by common descent)
• Direct observations
• Biological classification
• Homology in comparative anatomy
• Homology in development
• Homology in biochemistry
• Transition fossils

47. Evaluating the Evidence for
Evolution (by common descent)
• Direct observations
• Biological classification
• Homology in comparative anatomy
• Homology in development
• Homology in biochemistry
• Transition fossils
• Biogeography

48. Hypotheses to account for
distribution of organisms
• Separate origins
– penguins & auks, gazelle & deer
• Migration
– weeds, starlings, rabbits in Australia
• Vicariance
– Lednia stoneflies, meadowlarks
• Continental drift
– Cichlid fish in Africa & S. America
– Drumming stoneflies in N. hemisphere

50. “It is not the strongest of the
species that survive, but those
most responsive to change.”
- Charles Darwin

52. Same species or different species?

54. What is a species?
• Species = a group of potentially
interbreeding organisms.

56. What is a species?
• Species = a group of potentially
interbreeding organisms that produce fertile
offspring.

58. What is a species?
• Species = a group of potentially
interbreeding organisms that produce fertile
offspring, regularly in nature.

59. How do we decide if an organism is
an undescribed species?
• Biological species = a population of
potentially interbreeding organisms that
produce fertile offspring in nature
– Limitations? Advantages?
• Morphological species = a population of
organisms that look similar
– Limitations? Advantages?

65. How could new species arise?

66. What causes evolution?

68. Evolution of Jelly bellicus
0
1
2
3
4
5
6
7
8
breakfast lunch dinner
numberofsurvivors
green
green spots
orange
yellow spots
red
red spots
dk brown spots
tan spots

69. Evolution of Jelly bellicus
0
2
4
6
8
10
12
breakfast lunch dinner
numberofsurvivors
green
green spots
orange
yellow spots
red
red spots
dk brown spots
tan spots

70. Evolution of Jelly bellicus population shift
0
2
4
6
8
10
12
14
beginning after 1st meal after 2nd meal after 3rd meal
numberinpopulation
green
green spots
orange
yellow spots
red
red spots
dk brown spots
tan spots

73. How do we define evolution?
• Change in allele frequency of a
population’s gene pool,
• leading to change in organisms over time.
• Measure allele frequencies
How do we measure evolution?

74. Population Genetics Lab
• Question: How do selective pressure,
heterozygote advantage, and population size
affect allele frequencies and evolution?
• Hypotheses:
 selective pressure against an allele’s phenotype
will _______ the allele’s frequency.
 Heterozygote advantage will ________ the
frequency of a dominant allele.
 Allele frequencies will fluctuate more in ______
size populations.

75. Population Genetics Lab
• Methods
1.Begin each simulation by holding 1 dime
(representing a dominant allele) and 1 penny
(representing a recessive allele) in opposite
hands.
2.Each person selects a “mate” randomly in a
“hermaphroditic” population like slugs. Each
person holds a penny in one hand and a
dime in the other hand.

78. Population Genetics Lab Methods
3. Person 1 selects a partner’s hidden coin,
then person 2 selects a hidden coin.
4. The offspring is considered person 1’s
offspring and the genotype is determined by
what coins were selected.
5. Repeat the process for person 2’s offspring.
6. Record the genotpyes.
7. Exchange coins, if needed, from the class
gene pool.

79. Population Genetics Lab Methods
8. Record class data for numbers of
 homo. dom., heterozygous, homo. recessive
 frequencies of dominant & recessive alleles
8. Repeat for a total of 5 generations.
9. Repeat all steps for Case 2, 3, & 4
For Case 2 – selection:
• Homozygous recessive offspring die and
another mating must occur.

80. Population Genetics Lab Methods
For Case 3 – heterozygote advantage:
•Homozygous recessive offspring die and
•Homozygous dominant offspring must toss a
coin to see if the offspring lives or not. Head it
lives, tails it dies and must choose again.
For Case 4 – genetic drift:
•Class divides into 3 small groups,
reproductively isolated from each other.

82. Hardy-Weinberg Equilibrium
• p = % of dominant alleles in a population
• q = % of recessive alleles in a population
• % of homozygous dominant individuals =
• % of homozygous recessive individuals =
• % of heterozygous individuals =
• p + q = 1
• p2
+ 2pq + q2
= 1

83. Hardy-Weinberg Equilibrium
• Out of 1000 stoneflies collected, 160 are
apterous (no wings), a Mendelian recessive
trait.
• What are the percentages of homozygous
dominant stoneflies and heterozygous
stoneflies in the population?
• What percentage of each genotype will exist
in the next generation?
• Allele frequencies never change!

84. Conditions necessary for
Hardy-Weinberg Equilibrium
• No mutations
• No migration in or out of population
• No advantage of any phenotype over others
• Random mating
• Large population size

85. Forces that cause evolution
• Natural selection
• Mutation
• Gene flow
• Genetic drift

95. Forces that cause evolution
• Natural selection
• Mutation
• Gene flow
• Genetic drift
• Non-random mating

96. How could new species arise?

97. Prezygotic barriers
Habitat
Isolation
Temporal
Isolation
Behavioral
Isolation
Mechanical
Isolation
Gametic
Isolation
Individuals
of
different
species
MATING
ATTEMPT
FERTILIZATION
(a) (c) (e) (f)
(b)
(g)
(d)

98. Reduced Hybrid
Viability
Reduced Hybrid
Fertility
Hybrid
Breakdown
FERTILIZATION
VIABLE,
FERTILE
OFFSPRING
Postzygotic barriers
(k)
(h) (i)
(j)
(l)

100. • If humans evolved from other animals,
what type of animals would they most
likely have evolved from?
– Apes
• If humans evolved from some type of
apes, what evidence should exist?
– Transition fossils
– Anatomical & embryological homologies
– Molecular & biochemical homologies
– Behavioral similarities?

105. What makes people special?

106. Avoid these misconceptions
• Individuals evolve.
• Changes in environment cause beneficial
mutations and natural selection.
• Natural selection causes perfection.
• Natural selection works toward reaching a
predetermined goal.
– Were Alloperla sp. stoneflies supposed to
evolve to become a brilliant green color?
– Were humans supposed to become the way
they are?

109. “It would disturb me more to
find out that life couldn’t be
started in a laboratory. If life
can’t be started somehow in
this physical world, then how
did I get here?”
- Dr. Henry Eyring