Chapter 4Chapter 4

Evolution and Evolution and BiodiversityBiodiversity

Chapter Overview QuestionsChapter Overview Questions

How do scientists account for the How do scientists account for the development of life on earth?development of life on earth?

What is biological evolution by natural What is biological evolution by natural selection, and how can it account for the selection, and how can it account for the current diversity of organisms on the earth?current diversity of organisms on the earth?

How can geologic processes, climate change How can geologic processes, climate change and catastrophes affect biological evolution?and catastrophes affect biological evolution?

What is an ecological niche, and how does it What is an ecological niche, and how does it help a population adapt to changing the help a population adapt to changing the environmental conditions?environmental conditions?

Chapter Overview Questions (cont’d)Chapter Overview Questions (cont’d)

How do extinction of species and formation of How do extinction of species and formation of new species affect biodiversity?new species affect biodiversity?

What is the future of evolution, and what role What is the future of evolution, and what role should humans play in this future?should humans play in this future?

How did we become such a powerful species How did we become such a powerful species in a short time?in a short time?

Updates OnlineUpdates Online

The latest references for topics covered in this section can be found at The latest references for topics covered in this section can be found at the book companion website. Log in to the book’s e-resources page at the book companion website. Log in to the book’s e-resources page at www.thomsonedu.com to access InfoTrac articles. www.thomsonedu.com to access InfoTrac articles.

InfoTrac: Life After Earth: Imagining Survival Beyond This Terra InfoTrac: Life After Earth: Imagining Survival Beyond This Terra Firma. Richard Morgan. Firma. Richard Morgan. The New York TimesThe New York Times, August 1, 2006 , August 1, 2006 pF2(L).pF2(L).

InfoTrac: Rhinos Clinging to Survival in the Heart of Borneo, InfoTrac: Rhinos Clinging to Survival in the Heart of Borneo, Despite Poaching. Despite Poaching. US NewswireUS Newswire, March 17, 2006., March 17, 2006.

InfoTrac: Newfound Island Graveyard May Yield Clues to Dodo InfoTrac: Newfound Island Graveyard May Yield Clues to Dodo Life of Long Ago. Carl Zimmer. Life of Long Ago. Carl Zimmer. The New York TimesThe New York Times, July 4, 2006 , July 4, 2006 pF3(L).pF3(L).

NASA: Evolvable SystemsNASA: Evolvable Systems American Museum of Natural History: Tree of LifeAmerican Museum of Natural History: Tree of Life PBS: EvolutionPBS: Evolution

Video: Creation Vs. EvolutionVideo: Creation Vs. Evolution

This video clip is available in CNN Today This video clip is available in CNN Today Videos for Environmental Science, 2004, Videos for Environmental Science, 2004, Volume VII. Instructors, contact your local Volume VII. Instructors, contact your local sales representative to order this volume, sales representative to order this volume, while supplies last.while supplies last.

Core Case StudyCore Case StudyEarth: The Just-Right, Adaptable Earth: The Just-Right, Adaptable

PlanetPlanet

During the 3.7 billion During the 3.7 billion years since life years since life arose, the average arose, the average surface temperature surface temperature of the earth has of the earth has remained within the remained within the range of 10-20range of 10-20ooC.C.

Figure 4-1Figure 4-1

ORIGINS OF LIFEORIGINS OF LIFE

1 billion years of chemical change to form the 1 billion years of chemical change to form the first cells, followed by about 3.7 billion years first cells, followed by about 3.7 billion years of biological change. of biological change.

Figure 4-2Figure 4-2

Fig. 4-2, p. 84

Variety ofmulticellularorganismsform, firstin the seasand lateron land

Biological Evolution(3.7 billion years)

Chemical Evolution(1 billion years)

Formationof the

earth’searly

crust andatmosphere

Small organic

moleculesform in

the seas

Large organic

molecules(biopolymers)

form in the seas

First protocells form in the

seas

Single-cell prokaryotes

form in the seas

Single-celleukaryotes

form inthe seas

Biological Biological EvolutionEvolution

This has led to This has led to the variety of the variety of species we species we find on the find on the earth today.earth today.

Figure 4-2Figure 4-2

Fig. 4-3, p. 84

Modern humans (Homo sapiens sapiens) appear about 2 seconds before midnight

Recorded human history begins about 1/4 second before midnight

Origin of life (3.6-3.8 billion years ago)

Age of mammals

Age of reptiles

Insects and amphibians invade the land

First fossil record of animals

Plants begin invading land Evolution and

expansion of life

How Do We Know Which Organisms How Do We Know Which Organisms Lived in the Past?Lived in the Past?

Our knowledge Our knowledge about past life about past life comes from fossils, comes from fossils, chemical analysis, chemical analysis, cores drilled out of cores drilled out of buried ice, and DNA buried ice, and DNA analysis.analysis.

Figure 4-4Figure 4-4

EVOLUTION, NATURAL EVOLUTION, NATURAL SELECTION, AND ADAPTATIONSELECTION, AND ADAPTATION

Biological evolution by natural selection Biological evolution by natural selection involves the change in a population’s genetic involves the change in a population’s genetic makeup through successive generations.makeup through successive generations. genetic variabilitygenetic variability Mutations: random changes in the structure or Mutations: random changes in the structure or

number of DNA molecules in a cell that can be number of DNA molecules in a cell that can be inheritedinherited by offspring. by offspring.

Natural Selection and Adaptation: Natural Selection and Adaptation: Leaving More Offspring With Leaving More Offspring With

Beneficial TraitsBeneficial Traits Three conditions are necessary for biological Three conditions are necessary for biological

evolution:evolution: Genetic variability, traits must be heritable, trait Genetic variability, traits must be heritable, trait

must lead to must lead to differential reproductiondifferential reproduction. . An adaptive trait is any heritable trait that An adaptive trait is any heritable trait that

enables an organism to survive through enables an organism to survive through natural selection and reproduce better under natural selection and reproduce better under prevailing environmental conditions.prevailing environmental conditions.

Coevolution: A Biological Arms RaceCoevolution: A Biological Arms Race

Interacting species can engage in a back and Interacting species can engage in a back and forth genetic contest in which each gains a forth genetic contest in which each gains a temporary genetic advantage over the other.temporary genetic advantage over the other. This often happens between predators and prey This often happens between predators and prey

species.species.

Hybridization and Gene Swapping: Hybridization and Gene Swapping: other Ways to Exchange Genesother Ways to Exchange Genes

New species can arise through hybridization.New species can arise through hybridization. Occurs when individuals to two distinct species Occurs when individuals to two distinct species

crossbreed to produce an fertile offspring.crossbreed to produce an fertile offspring. Some species (mostly microorganisms) can Some species (mostly microorganisms) can

exchange genes without sexual reproduction.exchange genes without sexual reproduction. Horizontal gene transferHorizontal gene transfer

Limits on Adaptation through Limits on Adaptation through Natural SelectionNatural Selection

A population’s ability to adapt to new A population’s ability to adapt to new environmental conditions through natural environmental conditions through natural selection is limited by its gene pool and how selection is limited by its gene pool and how fast it can reproduce.fast it can reproduce. Humans have a relatively slow generation time Humans have a relatively slow generation time

(decades) and output (# of young) versus some (decades) and output (# of young) versus some other species.other species.

Common Myths about Evolution Common Myths about Evolution through Natural Selectionthrough Natural Selection

Evolution through natural selection is about Evolution through natural selection is about the most descendants.the most descendants. Organisms do not develop certain traits because Organisms do not develop certain traits because

they need them.they need them. There is no such thing as genetic perfection.There is no such thing as genetic perfection.

GEOLOGIC PROCESSES, CLIMATE GEOLOGIC PROCESSES, CLIMATE CHANGE, CATASTROPHES, AND CHANGE, CATASTROPHES, AND

EVOLUTIONEVOLUTION

The movement of solid (tectonic) plates The movement of solid (tectonic) plates making up the earth’s surface, volcanic making up the earth’s surface, volcanic eruptions, and earthquakes can wipe out eruptions, and earthquakes can wipe out existing species and help form new ones.existing species and help form new ones. The locations of continents and oceanic basins The locations of continents and oceanic basins

influence climate.influence climate. The movement of continents have allowed The movement of continents have allowed

species to move.species to move.

Fig. 4-5, p. 88

135 million years ago

Present65 million years ago

225 million years ago

Climate Change and Natural Climate Change and Natural SelectionSelection

Changes in climate throughout the earth’s Changes in climate throughout the earth’s history have shifted where plants and history have shifted where plants and animals can live.animals can live.

Figure 4-6Figure 4-6

Fig. 4-6, p. 89

Land above sea level

18,000years before present

Northern HemisphereIce coverage

Modern day(August)

Note:Modern sea ice

coveragerepresents

summer months

LegendContinental ice

Sea ice

Catastrophes and Natural SelectionCatastrophes and Natural Selection

Asteroids and meteorites hitting the earth and Asteroids and meteorites hitting the earth and upheavals of the earth from geologic upheavals of the earth from geologic processes have wiped out large numbers of processes have wiped out large numbers of species and created evolutionary species and created evolutionary opportunities by natural selection of new opportunities by natural selection of new species.species.

ECOLOGICAL NICHES AND ECOLOGICAL NICHES AND ADAPTATIONADAPTATION

Each species in an ecosystem has a specific Each species in an ecosystem has a specific role or way of life.role or way of life. Fundamental nicheFundamental niche: the full potential range of : the full potential range of

physical, chemical, and biological conditions and physical, chemical, and biological conditions and resources a species could theoretically use.resources a species could theoretically use.

Realized nicheRealized niche: to survive and avoid : to survive and avoid competition, a species usually occupies only part competition, a species usually occupies only part of its fundamental niche.of its fundamental niche.

Generalist and Specialist Species: Generalist and Specialist Species: Broad and Narrow NichesBroad and Narrow Niches

Generalist Generalist species tolerate species tolerate a wide range of a wide range of conditions.conditions.

Specialist Specialist species can species can only tolerate a only tolerate a narrow range of narrow range of conditions.conditions.

Figure 4-7Figure 4-7

Fig. 4-7, p. 91

Generalist specieswith a broad niche

Nu

mb

er o

f in

div

idu

als

Resource use

Specialist specieswith a narrow niche

Nicheseparation

Nichebreadth

Region of niche overlap

SPOTLIGHTSPOTLIGHTCockroaches: Nature’s Ultimate Cockroaches: Nature’s Ultimate

SurvivorsSurvivors 350 million years old350 million years old 3,500 different species3,500 different species Ultimate generalistUltimate generalist

Can eat almost anything.Can eat almost anything. Can live and breed almost Can live and breed almost

anywhere.anywhere. Can withstand massive Can withstand massive

radiation.radiation.

Figure 4-AFigure 4-A

Specialized Feeding NichesSpecialized Feeding Niches

Resource partitioning reduces competition Resource partitioning reduces competition and allows sharing of limited resources.and allows sharing of limited resources.

Figure 4-8Figure 4-8

Fig. 4-8, pp. 90-91

Piping plover feedson insects and tinycrustaceans on sandy beaches

(Birds not drawn to scale)

Black skimmerseizes small fishat water surface

Flamingofeeds on minuteorganismsin mud

Scaup and otherdiving ducks feed on mollusks, crustaceans,and aquatic vegetation

Brown pelican dives for fish,which it locates from the air

Avocet sweeps bill throughmud and surface water in search of small crustaceans,insects, and seeds

Louisiana heron wades intowater to seize small fish

Oystercatcher feeds onclams, mussels, and other shellfish into which it pries its narrow beak

Dowitcher probes deeplyinto mud in search ofsnails, marine worms,and small crustaceans

Knot (a sandpiper)picks up worms andsmall crustaceans leftby receding tide

Herring gull is atireless scavenger

Ruddy turnstone searches

under shells and pebbles

for small invertebrates

Evolutionary DivergenceEvolutionary Divergence

Each species has a Each species has a beak specialized to beak specialized to take advantage of take advantage of certain types of certain types of food resource.food resource.

Figure 4-9Figure 4-9

Fig. 4-9, p. 91

Maui Parrotbill

Fruit and seed eaters Insect and nectar eaters

Kuai Akialaoa

Amakihi

Crested Honeycreeper

Apapane

Akiapolaau

Unknown finch ancestor

Greater Koa-finch

Kona Grosbeak

SPECIATION, EXTINCTION, AND SPECIATION, EXTINCTION, AND BIODIVERSITYBIODIVERSITY

Speciation: A new species can arise when Speciation: A new species can arise when member of a population become isolated for member of a population become isolated for a long period of time.a long period of time. Genetic makeup changes, preventing them from Genetic makeup changes, preventing them from

producing fertile offspring with the original producing fertile offspring with the original population if reunited.population if reunited.

Geographic IsolationGeographic Isolation

……can lead to reproductive isolation, can lead to reproductive isolation, divergence of gene pools and speciation.divergence of gene pools and speciation.

Figure 4-10Figure 4-10

Fig. 4-10, p. 92

Different environmentalconditions lead to different selective pressures and evolution into two different species.

SouthernPopulation

Northernpopulation

Adapted to heat through lightweightfur and long ears, legs, and nose, which give off more heat.

Adapted to cold through heavier fur,short ears, short legs,short nose. White furmatches snow for camouflage.

Gray Fox

Arctic Fox

Spreadsnorthward

and southwardand separates

Early foxPopulation

Extinction: Lights OutExtinction: Lights Out

Extinction occurs Extinction occurs when the when the population population cannot adapt to cannot adapt to changing changing environmental environmental conditions.conditions.

The golden toad of Costa Rica’s The golden toad of Costa Rica’s Monteverde cloud forest has Monteverde cloud forest has become extinct because of become extinct because of changes in climate.changes in climate.

Figure 4-11Figure 4-11

Fig. 4-12, p. 93

Tertiary

Bar width represents relative number of living speciesEra Period

Species and families experiencing

mass extinction

Millions ofyears ago

Ordovician: 50% of animal families, including many trilobites.

Devonian: 30% of animal families, including agnathan and placoderm fishes and many trilobites.

500

345

Cambrian

Ordovician

Silurian

Devonian

Extinction

Extinction

Pal

eozo

icM

eso

zoic

Cen

ozo

ic

Triassic: 35% of animal families, including many reptiles and marine mollusks.

Permian: 90% of animal families, including over 95% of marine species; many trees, amphibians, most bryozoans and brachiopods, all trilobites.Carboniferous

Permian

Current extinction crisis causedby human activities. Many speciesare expected to become extinctwithin the next 50–100 years.Cretaceous: up to 80% of ruling reptiles (dinosaurs); many marine species including manyforaminiferans and mollusks.

Extinction

Extinction

Triassic

Jurassic

Cretaceous

250

180

65Extinction

ExtinctionQuaternary Today

Effects of Humans on BiodiversityEffects of Humans on Biodiversity

The scientific consensus is that human The scientific consensus is that human activities are decreasing the earth’s activities are decreasing the earth’s biodiversity.biodiversity.

Figure 4-13Figure 4-13

Fig. 4-13, p. 94

Marineorganisms

Terrestrialorganisms

Nu

mb

er o

f fa

mil

ies

Millions of years ago

Qu

ater

nar

y

Ter

tiar

y

Pre

-cam

bri

an

Cam

bri

an

Ord

ovi

cian

Sil

uri

an

Dev

on

ian

Car

bo

nif

ero

us

Jura

ssic

Dev

on

ian

Per

mia

n

Cre

tace

ou

s

GENETIC ENGINEERING AND THE GENETIC ENGINEERING AND THE FUTURE OF EVOLUTIONFUTURE OF EVOLUTION

We have used We have used artificial selectionartificial selection to change to change the genetic characteristics of populations with the genetic characteristics of populations with similar genes through similar genes through selective breedingselective breeding..

We have used We have used genetic engineeringgenetic engineering to transfer genes to transfer genes from one species to from one species to another.another.

Figure 4-15Figure 4-15

Genetic Engineering:Genetic Engineering: Genetically Modified Organisms (GMO)Genetically Modified Organisms (GMO)

GMOsGMOs useuse recombinant recombinant DNADNA genes or portions genes or portions

of genes from of genes from different different organisms.organisms.

Figure 4-14Figure 4-14

Fig. 4-14, p. 95

Insert modifiedplasmid into E. coli

Phase 1Make Modified Gene

Cell

Extract DNA

E. coli

Gene ofinterest

DNA

Identify and extract gene with desired trait

Geneticallymodifiedplasmid

Identify and remove portion of DNA withdesired trait

Remove plasmidfrom DNA of E. coli

Plasmid

ExtractPlasmid

Grow in tissueculture to

make copies

Insert extracted(step 2) into plasmid

(step 3)

Fig. 4-14, p. 95

Plant cell

Phase 2Make Transgenic Cell

Transfer plasmid to surface of microscopic metal particle

Use gene gun to injectDNA into plant cell

Agrobacterium inserts foreign DNA into plant cell to yield transgenic cell

Transfer plasmid copies to a carrier agrobacterium

Nucleus

E. Coli A. tumefaciens(agrobacterium)

Foreign DNA

Host DNA

Fig. 4-14, p. 95

Cell division oftransgenic cells

Phase 3Grow Genetically Engineered Plant

Transfer to soil

Transgenic plantswith new traits

Transgenic cell from Phase 2

Culture cells to form plantlets

Fig. 4-14, p. 95

Phase 3Grow Genetically Engineered Plant

Transgenic cell from Phase 2

Cell division oftransgenic cells

Culture cells to form plantlets

Transgenic plantswith new traits

Transfer to soil

Stepped Art

How Would You Vote?How Would You Vote?

To conduct an instant in-class survey using a classroom response To conduct an instant in-class survey using a classroom response system, access “JoinIn Clicker Content” from the PowerLecture main system, access “JoinIn Clicker Content” from the PowerLecture main menu for Living In the Environment.menu for Living In the Environment.

Should we legalize the production of human Should we legalize the production of human clones if a reasonably safe technology for clones if a reasonably safe technology for doing so becomes available?doing so becomes available? a. No. Human cloning will lead to widespread a. No. Human cloning will lead to widespread

human rights abuses and further overpopulation.human rights abuses and further overpopulation. b. Yes. People would benefit with longer and b. Yes. People would benefit with longer and

healthier lives. healthier lives.

THE FUTURE OF EVOLUTIONTHE FUTURE OF EVOLUTION

Biologists are learning to rebuild organisms Biologists are learning to rebuild organisms from their cell components and to clone from their cell components and to clone organisms.organisms. Cloning has lead to high miscarriage rates, rapid Cloning has lead to high miscarriage rates, rapid

aging, organ defects.aging, organ defects. Genetic engineering can help improve human Genetic engineering can help improve human

condition, but results are not always condition, but results are not always predictable.predictable. Do not know where the new gene will be located Do not know where the new gene will be located

in the DNA molecule’s structure and how that will in the DNA molecule’s structure and how that will affect the organism.affect the organism.

Controversy Over Controversy Over Genetic EngineeringGenetic Engineering

There are a number of privacy, ethical, legal There are a number of privacy, ethical, legal and environmental issues.and environmental issues.

Should genetic engineering and development Should genetic engineering and development be regulated?be regulated?

What are the long-term environmental What are the long-term environmental consequences?consequences?

Case Study:Case Study:How Did We Become Such a Powerful How Did We Become Such a Powerful

Species so Quickly?Species so Quickly? We lack:We lack:

strength, speed, agility.strength, speed, agility. weapons (claws, fangs), protection (shell).weapons (claws, fangs), protection (shell). poor hearing and vision.poor hearing and vision.

We have thrived as a species because of We have thrived as a species because of our:our: opposable thumbs, ability to walk upright, opposable thumbs, ability to walk upright,

complex brains (problem solving).complex brains (problem solving).