Chapter 4

Chapter 4Chapter 4

Evolution and Evolution and BiodiversityBiodiversity

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

PlanetPlanet

3.7 billion years 3.7 billion years since life arosesince life arose

average surface average surface temperature of the temperature of the earth has remained earth has remained within the range of within the range of 10-2010-20ooCC

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.


Animation: Stanley Miller’s ExperimentAnimation: Stanley Miller’s Experiment

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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

Animation: Evolutionary Tree of LifeAnimation: Evolutionary Tree of Life

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

Our knowledge about Our knowledge about past life comes from:past life comes from: FossilsFossils chemical analysischemical analysis cores drilled out of cores drilled out of

buried iceburied ice DNA and protein DNA and protein

analysisanalysis


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

Biological evolution Biological evolution by by natural selection natural selection change in a population’s genetic makeup through change in a population’s genetic makeup through

successive generationssuccessive generations genetic variabilitygenetic variability MutationsMutations::

• random changes in the structure or number of DNA random changes in the structure or number of DNA molecules in a cell that can be molecules in a cell that can be inheritedinherited by offspring. by offspring.

Animation: Stabilizing SelectionAnimation: Stabilizing Selection

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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 variabilityGenetic variability traits must be heritabletraits must be heritable trait must lead to trait must lead to differential reproductiondifferential reproduction

• An An adaptive trait adaptive trait is any heritable trait that enables an is any heritable trait that enables an organism to organism to survive through natural selection survive through natural selection and and reproduce better reproduce better under prevailing environmental under prevailing environmental conditions.conditions.

Survival of the FittestSurvival of the Fittest

Animation: Disruptive SelectionAnimation: Disruptive Selection

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Animation: Moth PopulationsAnimation: Moth Populations

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Animation: Adaptive TraitAnimation: Adaptive Trait

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

HybridizationHybridization Can create new speciesCan create new species Occurs when individuals to two distinct species Occurs when individuals to two distinct species

crossbreed to produce fertile offspringcrossbreed to produce 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

Changes are limited by the population’s gene Changes are limited by the population’s gene pool and how fast it can reproduce.pool and how 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

Organisms do not develop certain traits Organisms do not develop certain traits because they need them.because 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

movement of solid (tectonic) plates causes:movement of solid (tectonic) plates causes: volcanic eruptionsvolcanic eruptions earthquakes earthquakes

• can wipe out existing species and help form new onescan wipe out existing species and help form new ones Species movement/relocationSpecies movement/relocation

locations of continents and oceanic basins locations of continents and oceanic basins influence climateinfluence climate

Fig. 4-5, p. 88

135 million years ago

Present65 million years ago

225 million years ago

Video: Continental DriftVideo: Continental Drift

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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.


Video: Dinosaur DiscoveryVideo: Dinosaur Discovery

From ABC News, Environmental Science in the Headlines, 2005 DVD.From ABC News, Environmental Science in the Headlines, 2005 DVD.

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Catastrophes and Natural SelectionCatastrophes and Natural Selection

CatastrophiesCatastrophies Asteroids and meteorites hitting the earthAsteroids and meteorites hitting the earth upheavals of the earth from geologic processes upheavals of the earth from geologic processes

wipe out large numbers of specieswipe out large numbers of species create evolutionary opportunities by natural selection of create evolutionary opportunities by natural selection of

new speciesnew species• Adaptive radiationAdaptive radiation

ECOLOGICAL NICHES AND ECOLOGICAL NICHES AND ADAPTATIONADAPTATION

Fundamental nicheFundamental niche: : • the full potential range of physical, chemical, and the full potential range of physical, chemical, and

biological conditions and resources a species could biological conditions and resources a species could theoretically usetheoretically use

Realized nicheRealized niche: : • to survive and avoid competition, a species usually to survive and avoid competition, a species usually

occupies only part of its fundamental nicheoccupies only part of its fundamental niche

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

GeneralistGeneralist species species

tolerate a tolerate a wide rangewide range of of conditionsconditions

SpecialistSpecialist species can species can

only tolerate a only tolerate a narrow range narrow range of conditionsof conditions


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 anythingCan eat almost anything Can live and breed almost Can live and breed almost

anywhereanywhere Can withstand massive Can withstand massive

radiationradiation

Figure 4-AFigure 4-A

Specialized Feeding NichesSpecialized Feeding Niches

Resource partitioning Resource partitioning reduces competition reduces competition allows sharing of limited resourcesallows sharing of limited resources


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

Video: Frogs GaloreVideo: Frogs Galore

From ABC News, Environmental Science in the Headlines, 2005 DVD.From ABC News, Environmental Science in the Headlines, 2005 DVD.

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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.


SPECIATION, EXTINCTION, AND SPECIATION, EXTINCTION, AND BIODIVERSITYBIODIVERSITY

Speciation: Speciation: A new species can arise when member of a A new species can arise when member of a

population become isolated for a long period of population become isolated for a long period of time.time.• Genetic makeup changes, preventing them from Genetic makeup changes, preventing them from

producing fertile offspring with the original population if producing fertile offspring with the original population if reunitedreunited

Reproductive IsolationReproductive Isolation

Animation: Speciation on an ArchipelagoAnimation: Speciation on an Archipelago

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Animation: Evolutionary Tree DiagramsAnimation: Evolutionary Tree Diagrams

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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.


Extinction: Lights OutExtinction: Lights Out

ExtinctionExtinction occurs when the occurs when the

population population cannot adapt to cannot adapt to changing changing environmental environmental conditionsconditions

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.


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.


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

artificial selectionartificial selection Used to change the genetic characteristics of Used to change the genetic characteristics of

populations with similar genes through populations with similar genes through selective selective breedingbreeding

genetic engineeringgenetic engineering Used to transfer Used to transfer

genes from one genes from one species to anotherspecies to another Human to Human to

bacteriabacteriaFigure 4-15Figure 4-15

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

GMOsGMOs useuse

recombinant recombinant DNADNA

genes or genes or portions of genes portions of genes from different from different organisms.organisms.


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

Animation: Transgenic PlantsAnimation: Transgenic Plants

From ABC News, Biology in the Headlines, 2005 DVD.From ABC News, Biology in the Headlines, 2005 DVD.

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How Would You Vote?How Would You Vote?

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

CloningCloning rebuild organisms from their cell components rebuild organisms from their cell components

• has lead to: has lead to: high miscarriage rateshigh miscarriage rates rapid aging rapid aging organ defectsorgan defects

Genetic engineering Genetic engineering can help improve human conditioncan help improve human condition results are not always predictableresults are not always predictable

• Do not know where the new gene will be located in the Do not know where the new gene will be located in the DNA molecule’s structure and how that will affect the DNA molecule’s structure and how that will affect the organism.organism.

Video: Cloned PoochVideo: Cloned Pooch

From ABC News, Biology in the Headlines, 2005 DVD.From ABC News, Biology in the Headlines, 2005 DVD.

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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, agilitystrength, speed, agility weapons (claws, fangs), protection (shell)weapons (claws, fangs), protection (shell) poor hearing and visionpoor hearing and vision

We have thrived as a species because of We have thrived as a species because of our:our: opposable thumbsopposable thumbs ability to walk uprightability to walk upright complex brains (problem solving)complex brains (problem solving)

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