urry • cain • wasserman • minorsky • jackson • reece …4.5.pdfurry • cain • wasserman...

CAMPBELL BIOLOGY IN FOCUS

© 2014 Pearson Education, Inc.

Urry • Cain • Wasserman • Minorsky • Jackson • Reece

Lecture Presentations by Kathleen Fitzpatrick and Nicole Tunbridge

Unit 4.5

Broad Patterns of Evolution


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


Figure 23.1


Figure 23.UN01

Cryolophosaurus skull


Concept 23.1: The fossil record documents life’s history

▪ The fossil record reveals changes in the history of life on Earth


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


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


▪ 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


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


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


▪ 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


▪ 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


Table 23.1


Table 23.1a


Table 23.1b


▪ 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


▪ 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


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


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)


▪ Synapsids (300 mya) had single-pointed teeth, large temporal fenestra, and a jaw hinge between the articular and quadrate bones


▪ Therapsids (280 mya) had large dentary bones, long faces, and specialized teeth, including large canines


Figure 23.4b

Synapsid (300 mya)

Therapsid (280 mya)

Key to skull bonesArticularQuadrateDentarySquamosal

Temporalfenestra

Temporalfenestra

Hinge

Hinge


▪ 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


▪ Later cynodonts (220 mya) had teeth with complex cusp patterns and an additional jaw hinge between the dentary and squamosal bones


▪ 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


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)


▪ 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


Figure 23.5

Commonancestor oflineages Aand B

Millions of years ago

Lineage BLineage A

†

†

†

†

†

†

4 3 2 1 0


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

▪ 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


Figure 23.7

Eurasian Plate

PhilippinePlate

AustralianPlate

IndianPlate

ArabianPlate

AfricanPlate

AntarcticPlate

ScotiaPlate

NazcaPlate

SouthAmericanPlate

PacificPlate

CaribbeanPlate

NorthAmericanPlateJuan

de FucaPlate

Cocos Plate


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


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


▪ 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


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


▪ 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


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


The “Big Five” Mass Extinction Events

▪ In each of the five mass extinction events, more than 50% of Earth’s species became extinct


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


▪ The Permian mass 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


▪ 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


▪ 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


▪ 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


Figure 23.11

NORTHAMERICA

YucatánPeninsula

Chicxulubcrater


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


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


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


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


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


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


Figure 23.14

Ancestralmammal

ANCESTRALCYNODONT

Time (millions of years ago)250 200 150 100 50 0

Eutherians(5,010species)

Marsupials(324species)

Monotremes(5 species)


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


Figure 23.15

Close North Americanrelative, the tarweedCarlquistia muirii

Argyroxiphiumsandwicense

Dubautia linearisDubautia scabra

Dubautia waialealae

Dubautia laxa KAUAI5.1

millionyears

OAHU3.7

millionyears

HAWAII0.4

millionyears

1.3millionyearsMAUI

MOLOKAI

LANAI

N


Figure 23.15a

KAUAI5.1

millionyears

OAHU3.7

millionyears

HAWAII

0.4millionyears

1.3 million years MAUI

MOLOKAI

LANAI

N


▪ Studying genetic mechanisms of change can provide insight into large-scale evolutionary change

▪ Genes that program development influence the rate, timing, and spatial pattern of changes in an organism’s form as it develops into an adult

Concept 23.3: Major changes in body form can result from changes in the sequences and regulation of developmental genes


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


Figure 23.16

Chimpanzee infant Chimpanzee adult

Chimpanzee adultChimpanzee fetus

Human adultHuman fetus


▪ Another example of heterochrony can be seen in the skeletal structure of bat wings, which resulted from increased growth rates of the finger bones


Figure 23.17

Hand andfinger bones


▪ 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


Figure 23.18

Gills


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


▪ 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


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


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


Figure 23.19

Hox gene 6 Hox gene 7 Hox gene 8

About 400 mya

Drosophila Artemia

Ubx


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


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


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


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

Pigmentedlayer (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


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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