Post on 14-Jan-2017
CAMPBELL BIOLOGY IN FOCUS
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Urry • Cain • Wasserman • Minorsky • Jackson • Reece
Lecture Presentations by Kathleen Fitzpatrick and Nicole Tunbridge
23Broad Patterns of Evolution
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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
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Figure 23.1
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Figure 23.UN01
Cryolophosaurus skull
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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
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Figure 23.2
Dimetrodon
Coccosteus cuspidatus
Stromatolites
Tappania
Tiktaalik
Hallucigenia
Dickinsoniacostata
3,500
1,500600560
510500
400375
300270
200175
100mya
0.5 m
4.5 cm
1 cm
1 m
2.5 cm
Rhomaleosaurusvictor
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Figure 23.2a
Stromatolite crosssection
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Figure 23.2b
Stromatolites
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Figure 23.2c
Tappania
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Figure 23.2d
Dickinsonia costata
2.5 cm
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Figure 23.2e
Hallucigenia1 cm
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Figure 23.2f
Coccosteus cuspidatus4.5 cm
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Figure 23.2g
Tiktaalik
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Figure 23.2h
Dimetrodon0.5 m
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Figure 23.2i
Rhomaleosaurus victor1 m
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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
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Figure 23.3
½
¼⅛
Time (half-lives)
Frac
tion
of p
aren
tis
otop
e re
mai
ning
Remaining“parent”isotope
Accumulating“daughter”
isotope
1 2 4
1 16
3
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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
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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
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Table 23.1
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Table 23.1a
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Table 23.1b
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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
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Figure 23.4
OTHERTETRA-PODS
Synapsid (300 mya)
Reptiles(includingdinosaurs and birds)
†Very late (non-mammalian)cynodonts
†Dimetrodon
Mammals
Synapsids
Therapsids
Cynodonts
Key to skull bonesArticular DentaryQuadrate Squamosal
Early cynodont (260 mya)
Temporalfenestra(partial view)
Hinge
Temporalfenestra
Hinge
Temporalfenestra
Hinge Hinge
Therapsid (280 mya)New hinge
Very late cynodont (195 mya)
Original hinge
Later cynodont (220 mya)
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Figure 23.4a
OTHERTETRAPODS
Reptiles(includingdinosaurs and birds)
Mammals
†Very late (non-mammalian)cynodonts
†Dimetrodon
Cynodonts
Therapsids
Synapsids
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Synapsids (300 mya) had single-pointed teeth, large temporal fenestra, and a jaw hinge between the articular and quadrate bones
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Therapsids (280 mya) had large dentary bones, long faces, and specialized teeth, including large canines
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Figure 23.4b
Synapsid (300 mya)
Therapsid (280 mya)
Key to skull bonesArticularQuadrateDentarySquamosal
Temporalfenestra
Temporalfenestra
Hinge
Hinge
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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
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Later cynodonts (220 mya) had teeth with complex cusp patterns and an additional jaw hinge between the dentary and squamosal bones
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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
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Figure 23.4c
Key to skull bonesArticularQuadrateDentarySquamosal
Hinge
New hinge
Original hinge
Hinge
Temporalfenestra(partial view)
Early cynodont (260 mya)
Later cynodont (220 mya)
Very late cynodont (195 mya)
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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
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Figure 23.5
Commonancestor oflineages Aand B
Millions of years ago
Lineage BLineage A
†
†
†
†
†
†
4 3 2 1 0
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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
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Figure 23.6
Crust
Mantle
Outercore
Innercore
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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
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Figure 23.7
Eurasian Plate
PhilippinePlate
AustralianPlate
IndianPlate
ArabianPlate
AfricanPlate
AntarcticPlate
ScotiaPlate
NazcaPlate
SouthAmericanPlate
PacificPlate
CaribbeanPlate
NorthAmericanPlateJuan
de FucaPlate
Cocos Plate
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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
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Figure 23.8
Collision ofIndia withEurasia
Present-daycontinents
Laurasia andGondwanalandmasses
The supercontinentPangaeaPangaea
Gondwana
Laurasia
Antarctica
Eurasia
AfricaIndia
Australia
North America
SouthAmerica Madagascar
Cen
ozoi
cM
esoz
oic
Pale
ozoi
c251 mya
135 mya
65.5 mya
45 mya
Present
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Figure 23.8a
Laurasia andGondwanalandmasses
The supercontinentPangaeaPangaea
Gondwana
Laurasia
Mes
ozoi
cPa
leoz
oic251 mya
135 mya
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Figure 23.8b
Collision ofIndia withEurasia
Present-daycontinents
Antarctica
Eurasia
AfricaIndia
Australia
North America
SouthAmerica Madagascar
Cen
ozoi
c
65.5 mya
45 mya
Present
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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
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Figure 23.9
Millions of years ago (mya)
Mantellinae(Madagascar only):100 speciesRhacophorinae(India/southeastAsia): 310 species
India
Madagascar
56 mya88 mya
1
1
2
280 60 40 20 0
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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
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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
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The “Big Five” Mass Extinction Events
In each of the five mass extinction events, more than 50% of Earth’s species became extinct
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Figure 23.10
Time (mya)
Paleozoic Mesozoic Cenozoic
542 488 444 416 359 299 251 200 145 65.5 0E O S D C P Tr J PC N Q
0
100
200
300
400
500
600
700
800
900
1,000
1,100
EraPeriod
To
tal e
xtin
ctio
n ra
te(fa
mili
es p
er m
illio
n ye
ars)
:
Num
ber o
f fam
ilies
:
0
5
10
15
20
25
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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
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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 CO2 from the volcanoes
Reduced temperature gradient from equator to poles Oceanic anoxia from reduced mixing of ocean waters
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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
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Figure 23.11
NORTHAMERICA
YucatánPeninsula
Chicxulubcrater
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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
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Figure 23.12
Mass extinctions
Cooler WarmerRelative temperature
0 1 2−2 −1−3−2
−1
0
1
2
3R
elat
ive
extin
ctio
n ra
te o
fm
arin
e an
imal
gen
era
3 4
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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
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Figure 23.13
Time (mya)
Paleozoic Mesozoic Cenozoic
542 488 444 416 359 299 251 200 145 65.5 0E O S D C P Tr J PC N
Q
EraPeriod
0
10
20
30
40
50
Pred
ator
gen
era
(%)
Permian massextinction
Cretaceousmass extinction
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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
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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
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Figure 23.14
Ancestralmammal
ANCESTRALCYNODONT
Time (millions of years ago)250 200 150 100 50 0
Eutherians(5,010species)
Marsupials(324species)
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
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Figure 23.15
Close North Americanrelative, the tarweedCarlquistia muirii
Argyroxiphiumsandwicense
Dubautia linearisDubautia scabra
Dubautia waialealae
Dubautia laxa KAUAI5.1
millionyears OAHU
3.7millionyears
HAWAII0.4
millionyears
1.3millionyearsMAUI
MOLOKAI
LANAI
N
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Figure 23.15a
KAUAI5.1
millionyears
OAHU3.7
millionyears
HAWAII0.4
millionyears
1.3 million years MAUI
MOLOKAI
LANAI
N
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Figure 23.15b
Close North Americanrelative, the tarweedCarlquistia muirii
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Figure 23.15c
Dubautia waialealae
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Figure 23.15d
Dubautia laxa
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Figure 23.15e
Dubautia scabra
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Figure 23.15f
Argyroxiphiumsandwicense
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Figure 23.15g
Dubautia linearis
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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
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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
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Figure 23.16
Chimpanzee infant Chimpanzee adult
Chimpanzee adultChimpanzee fetus
Human adultHuman fetus
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Figure 23.16a
Chimpanzee infant Chimpanzee adult
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Another example of heterochrony can be seen in the skeletal structure of bat wings, which resulted from increased growth rates of the finger bones
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Figure 23.17
Hand andfinger bones
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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
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Figure 23.18
Gills
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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
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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
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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
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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
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Figure 23.19
Hox gene 6 Hox gene 7 Hox gene 8
About 400 mya
Drosophila Artemia
Ubx
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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
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Figure 23.UN03
Threespine stickleback(Gasterosteus aculeatus)
Ventral spines
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Figure 23.20
Hypothesis A: Differences insequence
Hypothesis B: Differences inexpression
Results
Marine stickleback embryo:expression in ventral spine andmouth regions
Lake stickleback embryo:expression only in mouthregions
Result: NoThe 283 amino acids of the Pitx1protein are identical.Result: Yes
Red arrows indicate regions of Pitx1expression.
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Figure 23.20a
Marine stickleback embryo:expression in ventral spine andmouth regions
Red arrows indicate regions of Pitx1expression.
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Figure 23.20b
Lake stickleback embryo:expression only in mouthregions
Red arrows indicate regions of Pitx1expression.
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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
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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
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Figure 23.21
(a) Patch of pigmented cellsPigmented cells(photoreceptors)
Nervefibers
Epithelium
Example: Patella, a limpet
(b) Eyecup
Nerve fibers
Pigmentedcells
Example: Pleurotomaria, aslit shell mollusc
(c) Pinhole camera-type eye
EpitheliumFluid-filledcavity
Opticnerve Pigmented
layer (retina)Example: Nautilus
(d) Eye with primitive lens
Cellularmass(lens)
Cornea
Optic nerve
Example: Murex, a marinesnail
Cornea
Lens
RetinaOpticnerve
(e) Complex camera lens-type eye
Example: Loligo, a squid
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Figure 23.21a
(a) Patch of pigmented cellsPigmented cells(photoreceptors)
Nervefibers
Epithelium
Example: Patella, a limpet
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Figure 23.21b
(b) Eyecup
Nerve fibers
Pigmentedcells
Example: Pleurotomaria, aslit shell mollusc
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Figure 23.21c
(c) Pinhole camera-type eye
EpitheliumFluid-filledcavity
Opticnerve Pigmented
layer (retina)Example: Nautilus
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Figure 23.21d
(d) Eye with primitive lens
Cellularmass(lens)
Cornea
Optic nerve
Example: Murex, a marinesnail
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Figure 23.21e
Cornea
Lens
RetinaOpticnerve
(e) Complex camera lens-type eye
Example: Loligo, a squid
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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
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Figure 23.22
Holocene
Pleistocene
Pliocene
Mio
cene
Equus
Sino
hipp
us
Meg
ahip
pus
Hyp
ohip
pus
Arc
haeo
hipp
us
Anchitherium
0
5
10
15
20
25
30
35
40
45
50
55
Olig
ocen
eEo
cene
Para
hipp
us
Pliohippus
Merychippus
Mesohippus
Mio
hipp
us
Hap
lohi
ppus
Pala
eoth
eriu
m
Pach
ynol
ophu
s
Prop
alae
othe
rium
Epih
ippu
s
Oro
hipp
us
Hyracotherium
Hyracotheriumrelatives
KeyGrazersBrowsers
Hip
pario
n
Neo
hipp
ario
n
Nan
nipp
us
Cal
lippu
s
Hip
pidi
on a
ndcl
ose
rela
tives
Mill
ions
of y
ears
ago
© 2014 Pearson Education, Inc.
Figure 23.22a
25
30
35
40
45
50
55
Olig
ocen
eEo
cene
Mesohippus
Mio
hipp
us
Hap
lohi
ppus
Pala
eoth
eriu
m
Pach
ynol
ophu
s
Prop
alae
othe
rium
Epih
ippu
s
Oro
hipp
us
Hyracotherium
Hyracotheriumrelatives
GrazersBrowsers
Mill
ions
of y
ears
ago
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Figure 23.22b
GrazersBrowsers
Mill
ions
of y
ears
ago
Holocene
Pleistocene
Pliocene
Mio
cene
Equus
Sino
hipp
us
Meg
ahip
pus
Hyp
ohip
pus
Arc
haeo
hipp
us
Anchitherium
0
5
10
15
20
Para
hipp
us
Pliohippus
Merychippus
Hip
pario
n
Neo
hipp
ario
n
Mio
-hi
ppus
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Figure 23.UN02
Paleocene Eocene
Millions of years ago (mya)
Species withplanktonic larvae
Species withnonplanktonic
larvae
65 60 55 50 45 40 35
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Figure 23.UN04
Flies andfleas
Caddisflies
Moths andbutterfliesHerbivory