Chapter 4 Evolution and Biodiversity. Chapter Overview Questions How do scientists account for the...

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

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

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

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

How do How do extinctionextinction of species and formation of of species and formation of newnew species affect biodiversity? species affect biodiversity?

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

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

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

Review:Review:4 Principles of Sustainability?4 Principles of Sustainability?

1.

2.

3.

4.

Core Case Study:Core Case Study:Why Should We Care about the Why Should We Care about the

American Alligator?American Alligator? Hunters wiped out Hunters wiped out

population to the point population to the point of near extinction.of near extinction.

1967- classified as 1967- classified as endangeredendangered

1975- numbers had 1975- numbers had reboundedrebounded

1977- reclassified as 1977- reclassified as threatenedthreatened

Figure 7-1Figure 7-1

Core Case Study:Core Case Study:Why Should We Care about the Why Should We Care about the

American Alligator?American Alligator? Alligators have Alligators have

important ecological important ecological role.role.

Alligators are a Alligators are a keystone specieskeystone species:: Influence on ecosystem Influence on ecosystem

is much greater than is much greater than their numbers would their numbers would suggestsuggest


Core Case Study:Core Case Study:American Alligator as Keystone American Alligator as Keystone

SpeciesSpecies Dig deep depressions (gator holes).Dig deep depressions (gator holes).

Hold water during dry spells, serve as refuges Hold water during dry spells, serve as refuges for aquatic life.for aquatic life.

Build nesting mounds.Build nesting mounds. provide nesting and feeding sites for birds.provide nesting and feeding sites for birds.

Keeps areas of open water free of vegetation Keeps areas of open water free of vegetation (swimming paths)(swimming paths)

Keep Keep gargar populations in check populations in check

Gator HolesGator Holes

Nesting MoundsNesting Mounds

Keep Waterways Keep Waterways ClearClear

Longnose Gar

Alligator Gar

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

PlanetPlanet Distance from sunDistance from sun SpinsSpins Size- molten mantle, Size- molten mantle,

retain atmosphereretain atmosphere Stratospheric Ozone Stratospheric Ozone

(2 billion years)(2 billion years)

21% Oxygen 21% Oxygen (several hundred million years)(several hundred million years)

Biodiversity & Biodiversity & SustainabilitySustainability

TempTemp


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.


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.


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 comes from fossilsfossils cores drilled out of cores drilled out of

buried iceburied ice analysis of analysis of protein protein

similaritiessimilarities DNA & RNA analysisDNA & RNA analysis..


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

Evolution in Seven Words:Evolution in Seven Words:

GenesGenes Mutate, Mutate, IndividualsIndividuals are Selected, are Selected, PopulationsPopulations Evolve Evolve

Natural selection acts on Natural selection acts on individualsindividuals, , but evolution occurs in but evolution occurs in populationspopulations

Three conditions are necessary for biological Three conditions are necessary for biological evolution:evolution:1. Genetic variability 2. traits must be 1. Genetic variability 2. traits must be heritableheritable

3. trait must lead to 3. trait must lead to differential reproductiondifferential reproduction. . An An adaptive traitadaptive trait is any heritable trait that 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.


Biological evolutionBiological evolution by natural selection by natural selection involves the involves the change in a change in a population’s genetic population’s genetic makeupmakeup through successive generations. through successive generations.

With With positive selection pressurepositive selection pressure, , advantageous traits help individuals to advantageous traits help individuals to survive long enough to have and raise their survive long enough to have and raise their young.young.

With With negative selection pressurenegative selection pressure, individuals , individuals die before they can reproduce.die before they can reproduce.


Advantageous traitsAdvantageous traits originate from genetic originate from genetic variability.variability.

Genetic variabilityGenetic variability occurs through… occurs through… mutationsmutations: random changes in the structure or : 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.• Exposure to Exposure to mutagensmutagens: radioactivity, x rays, certain : radioactivity, x rays, certain

chemicalschemicals• Random mistakesRandom mistakes in DNA duplication, or during RNA in DNA duplication, or during RNA

transcription and translation.transcription and translation.

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 selection is limited by its gene poolgene pool and how and how fast it can reproducefast 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

Yes:Yes: Biological evolution through natural Biological evolution through natural selection is about the selection is about the most descendantsmost descendants..

No:No: (Misunderstandings) (Misunderstandings) ““Survival of the fittest” means “survival of the Survival of the fittest” means “survival of the

biggest, fastest, or strongest”.biggest, fastest, or strongest”. Organisms develop certain traits because they Organisms develop certain traits because they

need them.need them. Species evolve towards genetic perfection.Species evolve towards genetic perfection.

New Species: HybridizationNew Species: Hybridization New species can arise through New species can arise through hybridizationhybridization..

Occurs when individuals to two distinct species Occurs when individuals to two distinct species crossbreed to produce a fertile offspring.crossbreed to produce a fertile offspring.

The red wolf is thought to be a coyote/wolf hybrid

New Species: Gene SwappingNew Species: Gene Swapping 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

BIODIVERSITYBIODIVERSITY

Why Should We Care About Why Should We Care About Biodiversity? Biodiversity?

Some consider it Some consider it ethicalethical to care about nature. to care about nature. Biodiversity provides us with:Biodiversity provides us with:

Natural ResourcesNatural Resources (food, water, wood, energy, (food, water, wood, energy, and medicines)and medicines)

Natural ServicesNatural Services (air and water purification, soil (air and water purification, soil fertility, waste disposal, pest control)fertility, waste disposal, pest control)

Aesthetic pleasureAesthetic pleasure

Biodiversity Loss and Species Biodiversity Loss and Species Extinction: Remember HIPPOExtinction: Remember HIPPO

HH for for habitat destructionhabitat destruction and and degradationdegradation I I for for invasive speciesinvasive species PP for for pollutionpollution PP for for human population growthhuman population growth OO for for overexploitationoverexploitation

ECOLOGICAL NICHES AND ECOLOGICAL NICHES AND ADAPTATION: Coastal GeorgiaADAPTATION: Coastal Georgia

Smooth cordgrass,

Spartina alterniflora,

Can grow in fresh water… …but it doesn’t in the wild.

Why not?

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.

Species Diversity and Niche Species Diversity and Niche Structure: Different Species Playing Structure: Different Species Playing

Different RolesDifferent Roles Biological communitiesBiological communities differ in the types and differ in the types and

numbers of speciesnumbers of species they contain and the they contain and the ecological rolesecological roles those species play. those species play.

Species diversitySpecies diversity has 2 components: has 2 components: species richnessspecies richness the number of different the number of different

species the ecosystem containsspecies the ecosystem contains species evennessspecies evenness the abundance of individuals the abundance of individuals

within each of those species.within each of those species.

Species Diversity and Niche StructureSpecies Diversity and Niche Structure

Niche structure: how many potential Niche structure: how many potential ecological niches occur, how they resemble ecological niches occur, how they resemble or differ, and how the species occupying or differ, and how the species occupying different niches interact.different niches interact.

Geographic location: species diversity is Geographic location: species diversity is highest in the tropics and declines as we highest in the tropics and declines as we move from the equator toward the poles.move from the equator toward the poles.

TYPES OF SPECIESTYPES OF SPECIES

Native, nonnative, indicator, keystone, and Native, nonnative, indicator, keystone, and foundation species play different ecological foundation species play different ecological roles in communities.roles in communities. NativeNative: those that normally live and thrive in a : those that normally live and thrive in a

particular community.particular community. Nonnative species a.k.a. invasive speciesNonnative species a.k.a. invasive species: those : those

that migrate, deliberately or accidentally that migrate, deliberately or accidentally introduced into a community.introduced into a community.

Indicator SpeciesIndicator Species: : Biological Smoke AlarmsBiological Smoke Alarms

Species that serve as Species that serve as early warningsearly warnings of of damage to a community or an ecosystem.damage to a community or an ecosystem. ““Canary in a coal mine”Canary in a coal mine” Presence or absence of Presence or absence of trout speciestrout species because because

they are sensitive to temperature and oxygen they are sensitive to temperature and oxygen levels.levels.

BirdsBirds- require a range of habitat- require a range of habitat LichensLichens- stay in one place and absorb from the - stay in one place and absorb from the

environmentenvironment AmphibiansAmphibians- vulnerable at any part of life cycle- vulnerable at any part of life cycle

Case Study: Case Study: Why are Amphibians Vanishing?Why are Amphibians Vanishing?

FrogsFrogs serve as serve as indicator speciesindicator species because because different parts of their life cycles can be easily different parts of their life cycles can be easily disturbed.disturbed. NextNext

Fig. 7-3, p. 147

Young frogAdult frog(3 years)

Sperm

SexualReproduction

Eggs Fertilized eggdevelopment Organ formation

Egg hatches

Tadpole

Tadpole developsinto frog

Case Study: Case Study: Why are Amphibians Vanishing?Why are Amphibians Vanishing?

Habitat loss and fragmentation.Habitat loss and fragmentation. Prolonged drought.Prolonged drought. Increases in ultraviolet radiation.Increases in ultraviolet radiation. Parasites.Parasites. Viral and Fungal diseases.Viral and Fungal diseases. Overhunting.Overhunting. Air OR water pollutionAir OR water pollution Natural immigration or deliberate introduction Natural immigration or deliberate introduction

of nonnative predators and competitors.of nonnative predators and competitors.

Keystone Species: Major PlayersKeystone Species: Major Players

KeystoneKeystone species help determine the types species help determine the types and numbers of other species in a and numbers of other species in a community thereby helping to sustain it.community thereby helping to sustain it.

Figures 7-4 and 7-5Figures 7-4 and 7-5

Foundation Species: Foundation Species: Other Major PlayersOther Major Players

Expansion of keystone species category.Expansion of keystone species category. Foundation species can Foundation species can create and enhancecreate and enhance

the physical habitats to benefit other species the physical habitats to benefit other species in a community.in a community. Elephants push over, break, or uproot trees, Elephants push over, break, or uproot trees,

creating forest openings promoting grass growth creating forest openings promoting grass growth for other species to utilize.for other species to utilize.

Alligators making “gator holes”Alligators making “gator holes”

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

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

Specialist speciesSpecialist species can only tolerate can only tolerate a narrow range of a narrow range of conditions. Exp: conditions. Exp: tiger salamander, tiger salamander, giant pandagiant panda


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

Evolutionary Divergence: Darwin’s Evolutionary Divergence: Darwin’s FinchesFinches

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.

NextNext

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

NATURAL SELECTION: DRIVEN BY NATURAL SELECTION: DRIVEN BY GEOLOGIC PROCESSES, CLIMATE GEOLOGIC PROCESSES, CLIMATE

CHANGE, & CATASTROPHESCHANGE, & CATASTROPHES

The movement of solid The movement of solid tectonic platestectonic plates making up the earth’s surface, making up the earth’s surface, volcanic volcanic eruptions, and earthquakeseruptions, and earthquakes can wipe out 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 Changes in climateclimate throughout the earth’s throughout the earth’s history have shifted where plants and history have shifted where plants and animals can live.animals can live.

NextNext

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

SPECIATION, EXTINCTION, AND SPECIATION, EXTINCTION, AND BIODIVERSITYBIODIVERSITY

Speciation:Speciation: A new species can arise when 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. Due to Due to natural selectionnatural selection over time, the over time, the

genetic makeup changesgenetic makeup changes, preventing them , preventing them from producing fertile offspring with the from producing fertile offspring with the original population if reunited.original population if reunited.

Catastrophes and Natural SelectionCatastrophes and Natural Selection

Asteroids and meteoritesAsteroids and meteorites hitting the earth and hitting the earth and upheavalsupheavals of the earth from geologic 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.

Geographic Isolation…Geographic Isolation…

……can can lead tolead to reproductive isolation, reproductive isolation, which which leads toleads to divergence of gene pools and divergence of gene pools and speciation.speciation.


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 Extinction occurs 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.


Categorizing Extinction RatesCategorizing Extinction Rates

Biologists estimate that 99.9% of all the Biologists estimate that 99.9% of all the species that ever existed are now extinct.species that ever existed are now extinct. Background extinction-Background extinction- a certain number of a certain number of

species disappearing at a slow rate due to species disappearing at a slow rate due to changes of local environmental conditionschanges of local environmental conditions• Estimate: 1-5 species per million per yearEstimate: 1-5 species per million per year

Mass depletion-Mass depletion- rates of extinction above rates of extinction above background level but not high enough to be background level but not high enough to be considered a mass extinction.considered a mass extinction.

Mass extinction-Mass extinction- a significant rise in extinction a significant rise in extinction rate above background level.rate above background level.

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.


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

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

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


We have used We have used genetic genetic engineeringengineering to transfer to transfer genes from one species to genes from one species to another (gene splicing)another (gene splicing) Takes half the time and costs Takes half the time and costs

less than crossbreeding.less than crossbreeding.

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..

Genetic Engineering:Genetic Engineering: GGenetically enetically MModified odified OOrganisms (GMO)rganisms (GMO)

GMOsGMOs useuse recombinant recombinant DNADNA genes or portions genes or portions

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


Case Study:Case Study:Species Diversity on IslandsSpecies Diversity on Islands

MacArthur and Wilson proposed the MacArthur and Wilson proposed the species species equilibrium modelequilibrium model a.k.a. a.k.a. theory of island theory of island biogeographybiogeography in the 1960’s. in the 1960’s.

Model projects that at some point the rates of Model projects that at some point the rates of immigration and extinction should reach an immigration and extinction should reach an equilibriumequilibrium based on: based on: Island sizeIsland size Distance to nearest mainlandDistance to nearest mainland

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 from their cell components and to clone clone organismsorganisms.. Cloning has lead to Cloning has lead to high miscarriage rates, rapid high miscarriage rates, rapid

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

condition, but results are not always condition, but results are not always predictable.predictable. Currently: We do not know where the new gene Currently: We do not know where the new gene

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

BiopharmingBiopharming

BiopharmingBiopharming is when humans use genetically is when humans use genetically engineered organisms for the production of engineered organisms for the production of consumables such asconsumables such as DrugsDrugs ChemicalsChemicals Human body partsHuman body parts

Which one of these have we not yet mastered?Which one of these have we not yet mastered?

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?Compared to other speciesCompared to other species, , we lackwe 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 our:We have thrived as a species because of our:•opposable thumbsopposable thumbs•ability to walk uprightability to walk upright

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

Ch 4 Final ThoughtsCh 4 Final Thoughts MicroevolutionMicroevolution- Traits changing in a species (e.g.color, - Traits changing in a species (e.g.color,

fur type, etc.)fur type, etc.)

Industrial MelanismIndustrial Melanism

in pepper moths:in pepper moths:

MacroevolutionMacroevolution- The development of new species- The development of new species

Ch 4 Final ThoughtsCh 4 Final Thoughts

Gradualism- species change Gradualism- species change slowly over time at a steady slowly over time at a steady rate of change (Darwin was rate of change (Darwin was wrong about this)wrong about this)

Punctuated Equilibrium- Long Punctuated Equilibrium- Long periods of stability punctuated periods of stability punctuated by peiods of rapid change, by peiods of rapid change, initiated by changes in the initiated by changes in the environment (evolutionary environment (evolutionary biologist Stephen Jay Gould)biologist Stephen Jay Gould)

# of

spe

cies

Time

# of

spe

cies

Time

Ch 4 Final ThoughtsCh 4 Final Thoughts

Natural SelectionNatural Selection happens to individuals, and leads happens to individuals, and leads to to differential reproductiondifferential reproduction (think about the wooly (think about the wooly worms lab)worms lab)

EvolutionEvolution happens to a population over time, and is happens to a population over time, and is ultimately understood as changes in ultimately understood as changes in gene gene frequenciesfrequencies within that population. within that population. Leads to microevolution in the short termLeads to microevolution in the short term Leads to macroevolution in the long termLeads to macroevolution in the long term

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.


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

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