Biology in Focus - Chapter 23

Biology in Focus - Chapter 23 - Broad Patterns of Evolution

1. CAMPBELL BIOLOGY IN FOCUS
© 2014 Pearson Education, Inc.
Urry • Cain • Wasserman • Minorsky • Jackson • Reece
Lecture Presentations by
Kathleen Fitzpatrick and Nicole Tunbridge
23
Broad Patterns
of Evolution

2. © 2014 Pearson Education, Inc.
Overview: Lost Worlds
Past organisms were very different from those now
alive
The fossil record shows evidence of macroevolution,
broad changes above the species level; for example
The emergence of terrestrial vertebrates
The impact of mass extinctions
The origin of flight in birds

3. © 2014 Pearson Education, Inc.
Figure 23.1

4. © 2014 Pearson Education, Inc.
Figure 23.UN01
Cryolophosaurus skull

5. © 2014 Pearson Education, Inc.
Concept 23.1: The fossil record documents life’s
history
The fossil record reveals changes in the history of
life on Earth
Video: Grand Canyon

6. © 2014 Pearson Education, Inc.
Figure 23.2
Dimetrodon
Coccosteus cuspidatus
Stromatolites
Tappania
Tiktaalik
Hallucigenia
Dickinsonia
costata
3,500
1,500
600
560
510
500
400
375
300
270
200
175
100
mya
0.5 m
4.5 cm
1 cm
1 m
2
.
5

c
m
Rhomaleosaurus
victor

7. © 2014 Pearson Education, Inc.
Figure 23.2a
Stromatolite cross
section

8. © 2014 Pearson Education, Inc.
Figure 23.2b
Stromatolites

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Figure 23.2c
Tappania

10. © 2014 Pearson Education, Inc.
Figure 23.2d
Dickinsonia costata
2
.
5

c
m

11. © 2014 Pearson Education, Inc.
Figure 23.2e
Hallucigenia
1 cm

12. © 2014 Pearson Education, Inc.
Figure 23.2f
Coccosteus cuspidatus
4.5 cm

13. © 2014 Pearson Education, Inc.
Figure 23.2g
Tiktaalik

14. © 2014 Pearson Education, Inc.
Figure 23.2h
Dimetrodon
0.5 m

15. © 2014 Pearson Education, Inc.
Figure 23.2i
Rhomaleosaurus victor
1 m

16. © 2014 Pearson Education, Inc.
The Fossil Record
Sedimentary rocks are deposited into layers called
strata and are the richest source of fossils
The fossil record indicates that there have been
great changes in the kinds of organisms on Earth at
different points in time

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Few individuals have fossilized, and even fewer
have been discovered
The fossil record is biased in favor of species that
Existed for a long time
Were abundant and widespread
Had hard parts

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How Rocks and Fossils Are Dated
Sedimentary strata reveal the relative ages of fossils
The absolute ages of fossils can be determined by
radiometric dating
A “parent” isotope decays to a “daughter” isotope at
a constant rate
Each isotope has a known half-life, the time
required for half the parent isotope to decay

19. © 2014 Pearson Education, Inc.
Figure 23.3
½
¼
⅛
Time (half-lives)
F
r
a
c
t
i
o
n

o
f

p
a
r
e
n
t
i
s
o
t
o
p
e

r
e
m
a
i
n
i
n
g
Remaining
“parent”
isotope
Accumulating
“daughter”
isotope
1 2 4
1
16
3

20. © 2014 Pearson Education, Inc.
Radiocarbon dating can be used to date fossils up
to 75,000 years old
For older fossils, some isotopes can be used to date
volcanic rock layers above and below the fossil

21. © 2014 Pearson Education, Inc.
The geologic record is a standard time scale
dividing Earth’s history into the Hadean, Archaean,
Proterozoic, and Phanerozoic eons
The Phanerozoic encompasses most of the time
that animals have existed on Earth
The Phanerozoic is divided into three eras: the
Paleozoic, Mesozoic, and Cenozoic
Major boundaries between geological divisions
correspond to extinction events in the fossil record
The Geologic Record
Animation: The Geologic Record

22. © 2014 Pearson Education, Inc.
Table 23.1

23. © 2014 Pearson Education, Inc.
Table 23.1a

24. © 2014 Pearson Education, Inc.
Table 23.1b

25. © 2014 Pearson Education, Inc.
The oldest known fossils are stromatolites, rocks
formed by the accumulation of sedimentary layers
on bacterial mats
Stromatolites date back 3.5 billion years ago
Prokaryotes were Earth’s sole inhabitants for more
than 1.5 billion years

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Early prokaryotes released oxygen into the
atmosphere through the process of photosynthesis
The increase in atmospheric oxygen that began 2.4
billion years ago led to the extinction of many
organisms
The eukaryotes flourished in the oxygen-rich
atmosphere and gave rise to multicellular organisms

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The Origin of New Groups of Organisms
Mammals belong to the group of animals called
tetrapods
The evolution of unique mammalian features can be
traced through gradual changes over time

28. © 2014 Pearson Education, Inc.
Figure 23.4
OTHER
TETRA-
PODS
Synapsid (300 mya)
Reptiles
(including
dinosaurs and birds)
†
Very late (non-
mammalian)
cynodonts
†
Dimetrodon
Mammals
S
y
n
a
p
s
i
d
s
T
h
e
r
a
p
s
i
d
s
C
y
n
o
d
o
n
t
s
Key to skull bones
Articular Dentary
Quadrate Squamosal
Early cynodont (260 mya)
Temporal
fenestra
(partial view)
Hinge
Temporal
fenestra
Hinge
Temporal
fenestra
Hinge Hinge
Therapsid (280 mya)
New hinge
Very late cynodont (195 mya)
Original hinge
Later cynodont (220 mya)

29. © 2014 Pearson Education, Inc.
Figure 23.4a
OTHER
TETRAPODS
Reptiles
(including
dinosaurs and birds)
Mammals
†
Very late (non-
mammalian)
cynodonts
†
Dimetrodon
C
y
n
o
d
o
n
t
s
T
h
e
r
a
p
s
i
d
s
S
y
n
a
p
s
i
d
s

30. © 2014 Pearson Education, Inc.
Synapsids (300 mya) had single-pointed teeth,
large temporal fenestra, and a jaw hinge between
the articular and quadrate bones

31. © 2014 Pearson Education, Inc.
Therapsids (280 mya) had large dentary bones,
long faces, and specialized teeth, including large
canines

32. © 2014 Pearson Education, Inc.
Figure 23.4b
Synapsid (300 mya)
Therapsid (280 mya)
Key to skull bones
Articular
Quadrate
Dentary
Squamosal
Temporal
fenestra
Temporal
fenestra
Hinge
Hinge

33. © 2014 Pearson Education, Inc.
Early cynodonts (260 mya) had large dentary
bones in the lower jaw, large temporal fenestra in
front of the jaw hinge, and teeth with several cusps

34. © 2014 Pearson Education, Inc.
Later cynodonts (220 mya) had teeth with complex
cusp patterns and an additional jaw hinge between
the dentary and squamosal bones

35. © 2014 Pearson Education, Inc.
Very late cynodonts (195 mya) lost the original
articular-quadrate jaw hinge
The articular and quadrate bones formed inner ear
bones that functioned in transmitting sound
In mammals, these bones became the hammer
(malleus) and anvil (incus) bones of the ear

36. © 2014 Pearson Education, Inc.
Figure 23.4c
Key to skull bones
Articular
Quadrate
Dentary
Squamosal
Hinge
New hinge
Original hinge
Hinge
Temporal
fenestra
(partial view)
Early cynodont (260 mya)
Later cynodont (220 mya)
Very late cynodont (195 mya)

37. © 2014 Pearson Education, Inc.
The history of life on Earth has seen the rise and fall
of many groups of organisms
The rise and fall of groups depend on speciation
and extinction rates within the group
Concept 23.2: The rise and fall of groups of
organisms reflect differences in speciation and
extinction rates

38. © 2014 Pearson Education, Inc.
Figure 23.5
Common
ancestor of
lineages A
and B
Millions of years ago
L
i
n
e
a
g
e

B
L
i
n
e
a
g
e

A
†
†
†
†
†
†
4 3 2 1 0

39. © 2014 Pearson Education, Inc.
Plate Tectonics
At three points in time, the landmasses of Earth
have formed a supercontinent: 1.1 billion, 600
million, and 250 million years ago
According to the theory of plate tectonics, Earth’s
crust is composed of plates floating on Earth’s
mantle

40. © 2014 Pearson Education, Inc.
Figure 23.6
Crust
Mantle
Outer
core
Inner
core

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Tectonic plates move slowly through the process of
continental drift
Oceanic and continental plates can separate, slide
past each other, or collide
Interactions between plates cause the formation of
mountains and islands and earthquakes
Video: Lava Flow
Video: Volcanic Eruption

42. © 2014 Pearson Education, Inc.
Figure 23.7
Eurasian Plate
Philippine
Plate
Australian
Plate
Indian
Plate
Arabian
Plate
African
Plate
Antarctic
Plate
Scotia
Plate
Nazca
Plate
South
American
Plate
Pacific
Plate
Caribbean
Plate
North
American
PlateJuan
de Fuca
Plate
Cocos Plate

43. © 2014 Pearson Education, Inc.
Consequences of Continental Drift
Formation of the supercontinent Pangaea about
250 million years ago had many effects
A deepening of ocean basins
A reduction in shallow water habitat
A colder and drier climate inland

44. © 2014 Pearson Education, Inc.
Figure 23.8
Collision of
India with
Eurasia
Present-day
continents
Laurasia and
Gondwana
landmasses
The supercontinent
Pangaea
Pangaea
G
o
n
d
w
a
n
a
Laurasia
Antarctica
Eurasia
Africa
India
Australia
N
orth A
m
erica
South
America
Madagascar
C
e
n
o
z
o
i
c
M
e
s
o
z
o
i
c
P
a
l
e
o
z
o
i
c
251 mya
135 mya
65.5 mya
45 mya
Present

45. © 2014 Pearson Education, Inc.
Figure 23.8a
Laurasia and
Gondwana
landmasses
The supercontinent
Pangaea
Pangaea
G
o
n
d
w
a
n
a
Laurasia
M
e
s
o
z
o
i
c
P
a
l
e
o
z
o
i
c
251 mya
135 mya

46. © 2014 Pearson Education, Inc.
Figure 23.8b
Collision of
India with
Eurasia
Present-day
continents
Antarctica
Eurasia
Africa
India
Australia
N
orth A
m
erica
South
America Madagascar
C
e
n
o
z
o
i
c
65.5 mya
45 mya
Present

47. © 2014 Pearson Education, Inc.
Continental drift can cause a continent’s climate to
change as it moves north or south
Separation of landmasses can lead to allopatric
speciation
For example, frog species in the subfamilies
Mantellinae and Rhacophorinae began to diverge
when Madagascar separated from India

48. © 2014 Pearson Education, Inc.
Figure 23.9
Millions of years ago (mya)
Mantellinae
(Madagascar only):
100 species
Rhacophorinae
(India/southeast
Asia): 310 species
India
Madagascar
56 mya88 mya
1
1
2
2
80 60 40 20 0

49. © 2014 Pearson Education, Inc.
The distribution of fossils and living groups reflects
the historic movement of continents
For example, the similarity of fossils in parts of South
America and Africa is consistent with the idea that
these continents were formerly attached

50. © 2014 Pearson Education, Inc.
Mass Extinctions
The fossil record shows that most species that have
ever lived are now extinct
Extinction can be caused by changes to a species’
environment
At times, the rate of extinction has increased
dramatically and caused a mass extinction
Mass extinction is the result of disruptive global
environmental changes

51. © 2014 Pearson Education, Inc.
The “Big Five” Mass Extinction Events
In each of the five mass extinction events, more
than 50% of Earth’s species became extinct

52. © 2014 Pearson Education, Inc.
Figure 23.10
Time (mya)
Paleozoic Mesozoic Cenozoic
542488444416359299251200145 65.5 0
EOSD C PTrJ PC N
Q
0
100
200
300
400
500
600
700
800
900
1,000
1,100
Era
Period



T
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)
:
N
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f

f
a
m
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s
:
0
5
10
15
20
25

53. © 2014 Pearson Education, Inc.
The Permian extinction defines the boundary
between the Paleozoic and Mesozoic eras 251
million years ago
This mass extinction occurred in less than 500,000
years and caused the extinction of about 96% of
marine animal species

54. © 2014 Pearson Education, Inc.
A number of factors might have contributed to these
extinctions
Intense volcanism in what is now Siberia
Global warming resulting from the emission of large
amounts of CO
2
from the volcanoes
Reduced temperature gradient from equator to poles
Oceanic anoxia from reduced mixing of ocean waters

55. © 2014 Pearson Education, Inc.
The Cretaceous mass extinction 65.5 million years
ago separates the Mesozoic from the Cenozoic
Organisms that went extinct include about half of all
marine species and many terrestrial plants and
animals, including most dinosaurs

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The presence of iridium in sedimentary rocks
suggests a meteorite impact about 65 million
years ago
Dust clouds caused by the impact would have
blocked sunlight and disturbed global climate
The Chicxulub crater off the coast of Mexico is
evidence of a meteorite collision that dates to the
same time

57. © 2014 Pearson Education, Inc.
Figure 23.11
NORTH
AMERICA
Yucatán
Peninsula
Chicxulub
crater

58. © 2014 Pearson Education, Inc.
Is a Sixth Mass Extinction Under Way?
Scientists estimate that the current rate of extinction
is 100 to 1,000 times the typical background rate
Extinction rates tend to increase when global
temperatures increase
Data suggest that a sixth, human-caused mass
extinction is likely to occur unless dramatic action
is taken

59. © 2014 Pearson Education, Inc.
Figure 23.12
Mass extinctions
Cooler Warmer
Relative temperature
0 1 2−2 −1−3
−2
−1
0
1
2
3
R
e
l
a
t
i
v
e

e
x
t
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a
n
i
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a
l

g
e
n
e
r
a
3 4

60. © 2014 Pearson Education, Inc.
Consequences of Mass Extinctions
Mass extinction can alter ecological communities and
the niches available to organisms
It can take 5–100 million years for diversity to recover
following a mass extinction
The type of organisms residing in a community can
change with mass extinction
For example, the percentage of marine predators
increased after the Permian and Cretaceous mass
extinctions
Mass extinction can pave the way for adaptive
radiations

61. © 2014 Pearson Education, Inc.
Figure 23.13
Time (mya)
Paleozoic Mesozoic Cenozoic
542488444416359 299251200145 65.5 0
E OS D C P Tr J PC N
Q
Era
Period
0
10
20
30
40
50
P
r
e
d
a
t
o
r

g
e
n
e
r
a

(
%
)
Permian mass
extinction
Cretaceous
mass extinction

62. © 2014 Pearson Education, Inc.
Adaptive Radiations
Adaptive radiation is the evolution of many
diversely adapted species from a common ancestor
Adaptive radiations may follow
Mass extinctions
The evolution of novel characteristics
The colonization of new regions

63. © 2014 Pearson Education, Inc.
Worldwide Adaptive Radiations
Mammals underwent an adaptive radiation after the
extinction of terrestrial dinosaurs
The disappearance of dinosaurs (except birds)
allowed for the expansion of mammals in diversity
and size
Other notable radiations include photosynthetic
prokaryotes, large predators in the Cambrian, land
plants, insects, and tetrapods

64. © 2014 Pearson Education, Inc.
Figure 23.14
Ancestral
mammal
ANCESTRAL
CYNODONT
Time (millions of years ago)
250 200 150 100 50 0
Eutherians
(5,010
species)
Marsupials
(324
species)
Monotremes
(5 species)

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Regional Adaptive Radiations
Adaptive radiations can occur when organisms
colonize new environments with little competition
The Hawaiian Islands are one of the world’s great
showcases of adaptive radiation
Animation: Allometric Growth

66. © 2014 Pearson Education, Inc.
Figure 23.15
Close North American
relative, the tarweed
Carlquistia muirii
Argyroxiphium
sandwicense
Dubautia linearis
Dubautia scabra
Dubautia waialealae
Dubautia laxa
KAUAI
5.1
million
years
OAHU
3.7
million
years
HAWAII
0.4
million
years
1.3
million
years
MAUI
MOLOKAI
LANAI
N

67. © 2014 Pearson Education, Inc.
Figure 23.15a
KAUAI
5.1
million
years
OAHU
3.7
million
years
HAWAII
0.4
million
years
1.3 million
years
MAUI
MOLOKAI
LANAI
N

68. © 2014 Pearson Education, Inc.
Figure 23.15b
Close North American
relative, the tarweed
Carlquistia muirii

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Figure 23.15c
Dubautia waialealae

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Figure 23.15d
Dubautia laxa

71. © 2014 Pearson Education, Inc.
Figure 23.15e
Dubautia scabra

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Figure 23.15f
Argyroxiphium
sandwicense

73. © 2014 Pearson Education, Inc.
Figure 23.15g
Dubautia linearis

74. © 2014 Pearson Education, Inc.
Studying genetic mechanisms of change can
provide insight into large-scale evolutionary change
Concept 23.3: Major changes in body form can
result from changes in the sequences and
regulation of developmental genes

75. © 2014 Pearson Education, Inc.
Effects of Development Genes
Genes that program development influence the
rate, timing, and spatial pattern of changes in an
organism’s form as it develops into an adult

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Changes in Rate and Timing
Heterochrony is an evolutionary change in the rate
or timing of developmental events
It can have a significant impact on body shape
The contrasting shapes of human and chimpanzee
skulls are the result of small changes in relative
growth rates

77. © 2014 Pearson Education, Inc.
Figure 23.16
Chimpanzee infant Chimpanzee adult
Chimpanzee adultChimpanzee fetus
Human adultHuman fetus

78. © 2014 Pearson Education, Inc.
Figure 23.16a
Chimpanzee infant Chimpanzee adult

79. © 2014 Pearson Education, Inc.
Another example of heterochrony can be seen in
the skeletal structure of bat wings, which resulted
from increased growth rates of the finger bones

80. © 2014 Pearson Education, Inc.
Figure 23.17
Hand and
finger bones

81. © 2014 Pearson Education, Inc.
Heterochrony can alter the timing of reproductive
development relative to the development of
nonreproductive organs
In paedomorphosis, the rate of reproductive
development accelerates compared with somatic
development
The sexually mature species may retain body
features that were juvenile structures in an ancestral
species

82. © 2014 Pearson Education, Inc.
Figure 23.18
Gills

83. © 2014 Pearson Education, Inc.
Changes in Spatial Pattern
Substantial evolutionary change can also result from
alterations in genes that control the placement and
organization of body parts
Homeotic genes determine such basic features as
where wings and legs will develop on a bird or how a
flower’s parts are arranged

84. © 2014 Pearson Education, Inc.
Hox genes are a class of homeotic genes that
provide positional information during animal
development
If Hox genes are expressed in the wrong location,
body parts can be produced in the wrong location
For example, in crustaceans, a swimming
appendage can be produced instead of a feeding
appendage

85. © 2014 Pearson Education, Inc.
The Evolution of Development
Adaptive evolution of both new and existing genes
may have played a key role in shaping the diversity
of life
Developmental genes may have been particularly
important in this process

86. © 2014 Pearson Education, Inc.
Changes in Gene Sequence
New morphological forms likely come from gene
duplication events that produce new developmental
genes
A possible mechanism for the evolution of six-legged
insects from a many-legged crustacean ancestor
has been demonstrated in lab experiments
Specific changes in the Ubx gene have been
identified that can “turn off” leg development

87. © 2014 Pearson Education, Inc.
Figure 23.19
Hox gene 6 Hox gene 7 Hox gene 8
About 400 mya
Drosophila Artemia
Ubx

88. © 2014 Pearson Education, Inc.
Changes in Gene Regulation
Changes in morphology likely result from changes
in the regulation of developmental genes rather than
changes in the sequence of developmental genes
For example, threespine sticklebacks in lakes have
fewer spines than their marine relatives
The gene sequence remains the same, but the
regulation of gene expression is different in the two
groups of fish

89. © 2014 Pearson Education, Inc.
Figure 23.UN03
Threespine stickleback
(Gasterosteus aculeatus)
Ventral spines

90. © 2014 Pearson Education, Inc.
Figure 23.20
Hypothesis A: Differences in
sequence
Hypothesis B: Differences in
expression
Results
Marine stickleback embryo:
expression in ventral spine and
mouth regions
Lake stickleback embryo:
expression only in mouth
regions
Result: No
The 283 amino acids of the Pitx1
protein are identical.
Result: Yes
Red arrows indicate regions of Pitx1
expression.

91. © 2014 Pearson Education, Inc.
Figure 23.20a
Marine stickleback embryo:
expression in ventral spine and
mouth regions
Red arrows indicate regions of Pitx1
expression.

92. © 2014 Pearson Education, Inc.
Figure 23.20b
Lake stickleback embryo:
expression only in mouth
regions
Red arrows indicate regions of Pitx1
expression.

93. © 2014 Pearson Education, Inc.
Concept 23.4: Evolution is not goal oriented
Evolution is like tinkering—it is a process in which
new forms arise by the slight modification of
existing forms

94. © 2014 Pearson Education, Inc.
Evolutionary Novelties
Most novel biological structures evolve in many
stages from previously existing structures
Complex eyes have evolved from simple
photosensitive cells independently many times
Exaptations are structures that evolve in one context
but become co-opted for a different function
Natural selection can only improve a structure in the
context of its current utility

95. © 2014 Pearson Education, Inc.
Figure 23.21
(a) Patch of pigmented cells
Pigmented cells
(photoreceptors)
Nerve
fibers
Epithelium
Example: Patella, a limpet
(b) Eyecup
Nerve fibers
Pigmented
cells
Example: Pleurotomaria, a
slit shell mollusc
(c) Pinhole camera-type eye
Epithelium
Fluid-filled
cavity
Optic
nerve
Pigmented
layer (retina)
Example: Nautilus
(d) Eye with primitive lens
Cellular
mass
(lens)
Cornea
Optic nerve
Example: Murex, a marine
snail
Cornea
Lens
Retina
Optic
nerve
(e) Complex camera lens-
type eye
Example: Loligo, a squid

96. © 2014 Pearson Education, Inc.
Figure 23.21a
(a) Patch of pigmented cells
Pigmented cells
(photoreceptors)
Nerve
fibers
Epithelium
Example: Patella, a limpet

97. © 2014 Pearson Education, Inc.
Figure 23.21b
(b) Eyecup
Nerve fibers
Pigmented
cells
Example: Pleurotomaria, a
slit shell mollusc

98. © 2014 Pearson Education, Inc.
Figure 23.21c
(c) Pinhole camera-type eye
Epithelium
Fluid-filled
cavity
Optic
nerve
Pigmented
layer (retina)
Example: Nautilus

99. © 2014 Pearson Education, Inc.
Figure 23.21d
(d) Eye with primitive lens
Cellular
mass
(lens)
Cornea
Optic nerve
Example: Murex, a marine
snail

100. © 2014 Pearson Education, Inc.
Figure 23.21e
Cornea
Lens
Retina
Optic
nerve
(e) Complex camera lens-
type eye
Example: Loligo, a squid

101. © 2014 Pearson Education, Inc.
Evolutionary Trends
Extracting a single evolutionary progression from
the fossil record can be misleading
Apparent trends should be examined in a broader
context
The species selection model suggests that
differential speciation success may determine
evolutionary trends
Evolutionary trends do not imply an intrinsic drive
toward a particular phenotype

102. © 2014 Pearson Education, Inc.
Figure 23.22
Holocene
Pleistocene
Pliocene
M
i
o
c
e
n
e
Equus
S
i
n
o
h
i
p
p
u
s
M
e
g
a
h
i
p
p
u
s
H
y
p
o
h
i
p
p
u
s
A
r
c
h
a
e
o
h
i
p
p
u
s
Anchitherium
0
5
10
15
20
25
30
35
40
45
50
55
O
l
i
g
o
c
e
n
e
E
o
c
e
n
e
P
a
r
a
h
i
p
p
u
s
Pliohippus
Merychippus
Mesohippus
M
i
o
h
i
p
p
u
s
H
a
p
l
o
h
i
p
p
u
s
P
a
l
a
e
o
t
h
e
r
i
u
m
P
a
c
h
y
n
o
l
o
p
h
u
s
P
r
o
p
a
l
a
e
o
t
h
e
r
i
u
m
E
p
i
h
i
p
p
u
s
O
r
o
h
i
p
p
u
s
Hyracotherium
Hyracotherium
relatives
Key
Grazers
Browsers
H
i
p
p
a
r
i
o
n
N
e
o
h
i
p
p
a
r
i
o
n
N
a
n
n
i
p
p
u
s
C
a
l
l
i
p
p
u
s
H
i
p
p
i
d
i
o
n

a
n
d
c
l
o
s
e

r
e
l
a
t
i
v
e
s
M
i
l
l
i
o
n
s

o
f

y
e
a
r
s

a
g
o

103. © 2014 Pearson Education, Inc.
Figure 23.22a
25
30
35
40
45
50
55
O
l
i
g
o
c
e
n
e
E
o
c
e
n
e
Mesohippus
M
i
o
h
i
p
p
u
s
H
a
p
l
o
h
i
p
p
u
s
P
a
l
a
e
o
t
h
e
r
i
u
m
P
a
c
h
y
n
o
l
o
p
h
u
s
P
r
o
p
a
l
a
e
o
t
h
e
r
i
u
m
E
p
i
h
i
p
p
u
s
O
r
o
h
i
p
p
u
s
Hyracotherium
Hyracotherium
relatives
Grazers
Browsers
M
i
l
l
i
o
n
s

o
f

y
e
a
r
s

a
g
o

104. © 2014 Pearson Education, Inc.
Figure 23.22b
Grazers
Browsers
M
i
l
l
i
o
n
s

o
f

y
e
a
r
s

a
g
o
Holocene
Pleistocene
Pliocene
M
i
o
c
e
n
e
Equus
S
i
n
o
h
i
p
p
u
s
M
e
g
a
h
i
p
p
u
s
H
y
p
o
h
i
p
p
u
s
A
r
c
h
a
e
o
h
i
p
p
u
s
Anchitherium
0
5
10
15
20
P
a
r
a
h
i
p
p
u
s
Pliohippus
Merychippus
H
i
p
p
a
r
i
o
n
N
e
o
h
i
p
p
a
r
i
o
n
M
i
o
-
h
i
p
p
u
s

105. © 2014 Pearson Education, Inc.
Figure 23.UN02
Paleocene Eocene
Millions of years ago (mya)
Species with
planktonic larvae
Species with
nonplanktonic
larvae
65 60 55 50 45 40 35

106. © 2014 Pearson Education, Inc.
Figure 23.UN04
Flies and
fleas
Caddisflies
Moths and
butterflies
Herbivory