Biodiversity:Biodiversity:

Evolution and Community Evolution and Community InteractionsInteractions

OverviewOverview

►What is biodiversity?What is biodiversity?►How did Earth get such a variety of life?How did Earth get such a variety of life?►What role does species interaction play?What role does species interaction play?►What are the benefits of biodiversity?What are the benefits of biodiversity?►How have humans impacted biodiversity?How have humans impacted biodiversity?►What is being done to maintain What is being done to maintain

biodiversity?biodiversity?

Essential QuestionsEssential Questions

► Be able to describe how the earth is “just Be able to describe how the earth is “just right” for liferight” for life

► What is evolution? How has evolution lead What is evolution? How has evolution lead to the current diversity of organisms?to the current diversity of organisms?

► What is an ecological niche? How does it What is an ecological niche? How does it relate to adaptation to changing relate to adaptation to changing environmental conditions?environmental conditions?

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

Evolution: The Origin of Evolution: The Origin of BiodiversityBiodiversity

► What evolution isWhat evolution is Descent with ModificationDescent with Modification A regular progression in the complexity of life forms on A regular progression in the complexity of life forms on

EarthEarth► Chemical vs BiologicalChemical vs Biological

Chemical: How did the first life forms originate?Chemical: How did the first life forms originate?► Many theories, Little consensusMany theories, Little consensus

Biological: How has life changed over time?Biological: How has life changed over time?► Darwin and Natural Selection: Accepted by most scientistsDarwin and Natural Selection: Accepted by most scientists

► EvidenceEvidence Fossils (Video clip)Fossils (Video clip) AnatomyAnatomy MolecularMolecular

Earth: The Just Right PlanetEarth: The Just Right Planet

► TemperatureTemperature Distance from SunDistance from Sun Geothermal energy from coreGeothermal energy from core Temperature fluctuated only 10-20Temperature fluctuated only 10-20ooC over 3.7 billion years C over 3.7 billion years

despite 30-40% increase in solar outputdespite 30-40% increase in solar output► WaterWater exists in 3 phases exists in 3 phases► Right size (=gravitational mass to keep Right size (=gravitational mass to keep

atmosphere)atmosphere)► Resilient and adaptiveResilient and adaptive► Each species here today represents a long chain of Each species here today represents a long chain of

evolution and each plays a role in its respective evolution and each plays a role in its respective ecosystemecosystem

Summary of Evolution of LifeSummary of Evolution of Life

Formationof the

earth’searly

crust andatmosphere

Small organic

moleculesform in

the seas

Large organic

molecules(biopolymers)

form inthe seas

First protocells

form inthe seas

Single-cellprokaryotes

form inthe seas

Single-celleukaryotes

form inthe seas

Variety ofmulticellularorganismsform, first

in the seas and lateron land

Chemical Evolution(1 billion years)

Biological Evolution(3.7 billion years)

Origins of Life on EarthOrigins of Life on Earth4.7-4.8 Billion Year History4.7-4.8 Billion Year History

► Evidence from chemical analysis and Evidence from chemical analysis and measurements of radioactive elements in measurements of radioactive elements in primitive rocks and fossils. primitive rocks and fossils.

► Life developed over two main phases:Life developed over two main phases: Chemical evolution (took about 1 billion years)Chemical evolution (took about 1 billion years)

► Organic molecules, proteins, polymers, and chemical Organic molecules, proteins, polymers, and chemical reactions to form first “protocells”reactions to form first “protocells”

Biological evolution (3.7 billion years)Biological evolution (3.7 billion years)► From single celled prokaryotic bacteria to eukaryotic From single celled prokaryotic bacteria to eukaryotic

creatures to eukaryotic multicellular organisms creatures to eukaryotic multicellular organisms (diversification of species)(diversification of species)

KWLKWL Musical Showoff Musical Showoff

►Write down what you Write down what you KKnow and now and WWant ant to know about the following:to know about the following: Definition and relationship among:Definition and relationship among:

►EvolutionEvolution►Natural SelectionNatural Selection►AdaptationAdaptation

Biodiversity = Speciation – ExtinctionBiodiversity = Speciation – Extinction►Musical CirclesMusical Circles►Discuss what you Discuss what you LLearnedearned

Biological EvolutionBiological Evolution

Fossils present but rare

Evolution and expansion of life

Fossils become abundant

Plants invade the land

Age of reptiles

Age of mammals

Insects and amphibians invade the land

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

Recorded human history begins 1/4 second before midnight

Origin of life (3.6–3.8 billion years ago)

Fossil RecordFossil Record► Most of what we know of the history of life Most of what we know of the history of life

on earth comes from fossils (SJ Gould)on earth comes from fossils (SJ Gould)► Give us physical evidence of organismsGive us physical evidence of organisms

Show us internal structureShow us internal structure► Uneven and incomplete record of speciesUneven and incomplete record of species

We have fossils for 1% of species believed to We have fossils for 1% of species believed to have lived on earthhave lived on earth

Some organisms left no fossils, others Some organisms left no fossils, others decomposed, others have yet to be found. decomposed, others have yet to be found.

► Other info from ancient rocks, ice core, DNA Other info from ancient rocks, ice core, DNA ► The whale as an exampleThe whale as an example Other evidence Other evidence

herehere

Evidence of Environmental Evidence of Environmental Effect:Effect:

Convergent EvolutionConvergent Evolution

•Analogy•Similarity in body parts in different organisms•Attributable to similar environmental pressures

Evidence of Common Ancestry:Evidence of Common Ancestry:Divergent EvolutionDivergent Evolution

•Homology •Similarity in body parts in different organisms•Attributable to descent from a common ancestor

Natural SelectionNatural Selection

►Genetic VariationGenetic Variation Variations are heritableVariations are heritable

►Overproduction of OffspringOverproduction of Offspring MalthusMalthus

►Struggle for ExistenceStruggle for Existence Competition, Predation, etc…Competition, Predation, etc…

►Differential Survival and ReproductionDifferential Survival and Reproduction Fitness = # of offspring left to next Fitness = # of offspring left to next

generationgeneration

Darwinian Natural SelectionDarwinian Natural Selection

► Three conditions necessary for evolution by Three conditions necessary for evolution by natural selection to occur: natural selection to occur: Natural variability for a trait in a populationNatural variability for a trait in a population Trait must be heritable (has a genetic basis so Trait must be heritable (has a genetic basis so

that it can be passed onto offspring)that it can be passed onto offspring) Trait must lead to differential reproductionTrait must lead to differential reproduction

► Must allow some members of the population to leave Must allow some members of the population to leave more offspring than other members of the population more offspring than other members of the population w/o trait)w/o trait)

► Grant’s FinchesGrant’s Finches► A heritable trait that enables organisms to A heritable trait that enables organisms to

survive and reproduce is called an survive and reproduce is called an adaptation (Lamark is wrong…)adaptation (Lamark is wrong…)

Tutorial

What is Adaptation?What is Adaptation?

►NounNoun Result of Natural SelectionResult of Natural Selection Favorable trait that has accumulated in a Favorable trait that has accumulated in a

species through years of natural selectionspecies through years of natural selection

►VerbVerb The process of accumulating favorable traitsThe process of accumulating favorable traits Occurs OVER TIME to the POPULATION AS A Occurs OVER TIME to the POPULATION AS A

WHOLE (i.e., Individuals do not adapt, WHOLE (i.e., Individuals do not adapt, populations do)populations do)

Take Home #1Take Home #1

► When faced with a change in environmental When faced with a change in environmental condition, a population of a species can:condition, a population of a species can: Adapt via natural selectionAdapt via natural selection Migrate (if possible) to an area with more Migrate (if possible) to an area with more

favorable conditions (Mars & Atlantis?)favorable conditions (Mars & Atlantis?) Become extinctBecome extinct

► Natural selection can only act on inherited Natural selection can only act on inherited alleles already present in the population—do alleles already present in the population—do not think that the environment creates not think that the environment creates favorable heritable characteristics! favorable heritable characteristics!

Steps of EvolutionSteps of Evolution

► Genetic variation is added to genotype by mutationGenetic variation is added to genotype by mutation► Mutations lead to changes in the phenotypeMutations lead to changes in the phenotype► Phenotype is acted upon by nat’l selectionPhenotype is acted upon by nat’l selection► Individuals more suited to environment produce Individuals more suited to environment produce

more offspring (contribute more to total gene pool more offspring (contribute more to total gene pool of population)of population)

► Population’s gene pool changes over timePopulation’s gene pool changes over time► Speciation may occur if geographic and Speciation may occur if geographic and

reproductive isolating mechanisms exist…reproductive isolating mechanisms exist…► Natural Selection in action ...Natural Selection in action ...► A demonstration...A demonstration...

Predator Prey Predator Prey Cycles:Cycles:

Who Controls Whom?Who Controls Whom?

The Lotka-Volterra EquationsHistorical Data

CoevolutionCoevolution► Interactions between species can cause Interactions between species can cause

microevolutionmicroevolution Changes in the gene pool of one species can Changes in the gene pool of one species can

cause changes in the gene pool of the othercause changes in the gene pool of the other► Adaptation follows adaptation in something Adaptation follows adaptation in something

of a long term “arms race” between of a long term “arms race” between interacting populations of different interacting populations of different populationspopulations The Red Queen EffectThe Red Queen Effect

► Can also be symbiotic coevolutionCan also be symbiotic coevolution Angiosperms and insects (pollinators)Angiosperms and insects (pollinators) Corals and zooxanthellae Corals and zooxanthellae RhizobiumRhizobium bacteria and legume root nodules bacteria and legume root nodules

Co-Evolution: Species affecting each Co-Evolution: Species affecting each otherother

► The Red Queen EffectThe Red Queen Effect ""NowNow, here, you see, it , here, you see, it

takes all the running you takes all the running you can do, to keep in the can do, to keep in the same place. If you want same place. If you want to get somewhere else, to get somewhere else, you must run at least you must run at least twice as fast as that!" twice as fast as that!"

Evolution is a continuous, Evolution is a continuous, never ending, ever never ending, ever changing processchanging process

Monarchs, Milkweed and Monarchs, Milkweed and ViceroysViceroys

•Many Insects eat milkweed•Milkweed evolves a sticky latex that deters herbivory•Monarchs evolve an enzyme that thins the latex•Monarchs have a food source without competitors•The latex makes Monarchs distasteful to their predators•Viceroys look like Monarchs but taste fine

•Batesian Mimicry = False Advertising

Orchids and WaspsOrchids and Wasps

Flowers using insects

EvolutionEvolution► The change in a POPULATION’S genetic makeup The change in a POPULATION’S genetic makeup

(gene pool) over time (successive generations)(gene pool) over time (successive generations) Those with the best phenotype and genotype survive to Those with the best phenotype and genotype survive to

reproduce and pass on traitsreproduce and pass on traits All species descended from earlier ancestor speciesAll species descended from earlier ancestor species

► MicroevolutionMicroevolution Small genetic changes in a population such as Small genetic changes in a population such as

the spread of a mutation or the change in the the spread of a mutation or the change in the frequency of a single allele due to selection frequency of a single allele due to selection (changes to gene pool)(changes to gene pool)

Not possible without genetic variability in a Not possible without genetic variability in a pop…pop…

► MacroevolutionMacroevolution Long term large scale evolutionary changes Long term large scale evolutionary changes

through which new species are formed and through which new species are formed and others are lost through extinctionothers are lost through extinction

MicroevolutionMicroevolution► Changes in a population’s gene pool over time.Changes in a population’s gene pool over time.

Genetic variability within a population is the catalystGenetic variability within a population is the catalyst► Four Processes cause MicroevolutionFour Processes cause Microevolution

MutationMutation (random changes in DNA— (random changes in DNA—ultimate source ultimate source of new allelesof new alleles) [stop little]) [stop little]

►Exposure to mutagens or random mistakes in Exposure to mutagens or random mistakes in copyingcopying

►Random/unpredictable relatively rareRandom/unpredictable relatively rare Natural SelectionNatural Selection (best produce most offspring) (best produce most offspring) Gene flowGene flow (movement of genes between pop’s) (movement of genes between pop’s) Genetic driftGenetic drift (change in gene pool due to (change in gene pool due to

random/chance events)random/chance events)► Peppered moth of England; El Nino GalapagosPeppered moth of England; El Nino Galapagos

Gene Flow and Genetic DriftGene Flow and Genetic Drift

► Gene FlowGene Flow Flow of allelesFlow of alleles

►Emigration and immigration of Emigration and immigration of

individualsindividuals

► Genetic DriftGenetic Drift Random change in allele frequencies over Random change in allele frequencies over

generations brought about by chancegenerations brought about by chance

In the absence of other forces, drift leads In the absence of other forces, drift leads

to loss of genetic diversity to loss of genetic diversity

Genetic DriftGenetic Drift

► Magnitude of drift is greatest in small Magnitude of drift is greatest in small populationspopulations

Three types of Natural Three types of Natural SelectionSelection

► DirectionalDirectional Allele frequencies shift to favor individuals at one Allele frequencies shift to favor individuals at one

extreme of the normal rangeextreme of the normal range► Only one side of the distribution reproduceOnly one side of the distribution reproduce► Population looks different over timePopulation looks different over time

Peppered moths and genetic resistance to Peppered moths and genetic resistance to pesticides among insects and antibiotics in pesticides among insects and antibiotics in bacteriabacteria

► StabilizingStabilizing Favors individuals with an average genetic makeupFavors individuals with an average genetic makeup

► Only the middle reproduceOnly the middle reproduce► Population looks more similar over time Population looks more similar over time (eliminates extremes)(eliminates extremes)

► Diversifying (Disruptive)Diversifying (Disruptive) Environmental conditions favor individuals at both Environmental conditions favor individuals at both

ends of the genetic spectrum ends of the genetic spectrum ► Population split into two groupsPopulation split into two groups

Directional Change in the Directional Change in the Range of VariationRange of Variation

► Directional SelectionDirectional Selection Shift in allele frequency Shift in allele frequency

in a consistent in a consistent

directiondirection

► Phenotypic Variation Phenotypic Variation

in a population of in a population of

butterfliesbutterflies

The Case of the Peppered The Case of the Peppered MothsMoths

► Industrial revolutionIndustrial revolution Pollution darkened tree Pollution darkened tree

trunkstrunks

► Camouflage of moths Camouflage of moths

increases survival increases survival

from predatorsfrom predators

► Directional selection Directional selection

caused a shift away caused a shift away

from light-gray from light-gray

towards dark-gray towards dark-gray

mothsmoths

Directional SelectionDirectional Selection

► Pesticide ResistancePesticide Resistance Pest resurgencePest resurgence

► Antibiotic ResistanceAntibiotic Resistance

► Grant’s Finch Beak DataGrant’s Finch Beak Data► With directional selection, allele With directional selection, allele

frequencies tend to shift in response to frequencies tend to shift in response to directional changes in the environmentdirectional changes in the environment

Selection Against or in Favor of Selection Against or in Favor of Extreme PhenotypesExtreme Phenotypes

► Stabilizing SelectionStabilizing Selection Intermediate forms Intermediate forms

of a trait are favoredof a trait are favored

Alleles that specify Alleles that specify

extreme forms are extreme forms are

eliminated from a eliminated from a

populationpopulation

Clutch size in birdsClutch size in birds

Shell size in turtlesShell size in turtles

percen

t of

po

pu

lation

20

15

10

5

1 2 3 4 5 6 7 8 9 10 11

birth weight (pounds)

100

70

50

30

20

10

5

3

2

percen

t of

mo

rtality

An Example of Stabilizing An Example of Stabilizing SelectionSelection

Selection Against or in Favor of Selection Against or in Favor of Extreme PhenotypesExtreme Phenotypes

► Disruptive Disruptive

SelectionSelection Both forms at Both forms at

extreme ends are extreme ends are

favoredfavored

Intermediate forms Intermediate forms

are eliminatedare eliminated

Bill size in African Bill size in African

finchesfinches

Fig. 18.9, p. 289

10

20

30

40

50

60

Nu

mb

er of

ind

ividu

als

10 1.12 15.7 18.5

Widest part of lower bill(millimeters)

Special Types of SelectionSpecial Types of Selection

► Balancing Balancing

selectionselection Balanced Balanced

polymorphismpolymorphism

►Sickle-Cell Sickle-Cell

AnemiaAnemia

►Malaria Malaria

Distribution of Malaria

Sickle Cell Trait

What is a Species?What is a Species?

► Morphological Species ConceptMorphological Species Concept Based on appearance aloneBased on appearance alone

► Biological Species ConceptBiological Species Concept A species is one or more populations of A species is one or more populations of

individuals that are interbreeding under individuals that are interbreeding under

natural conditions and producing fertile natural conditions and producing fertile

offspring, and are reproductively isolated offspring, and are reproductively isolated

from other such populationsfrom other such populations

Key Concepts:Key Concepts:

► A species consist of one or more A species consist of one or more

populations of individuals that can populations of individuals that can

interbreed and produce offspringinterbreed and produce offspring

► Populations of a species have a Populations of a species have a

shared genetic historyshared genetic history

► Speciation is the process by which Speciation is the process by which

daughter species evolve from a daughter species evolve from a

parent speciesparent species

Key Concepts:Key Concepts:

►Geographic barriers can start Geographic barriers can start

the process of speciationthe process of speciation Allopatric speciationAllopatric speciation

►A species can form within the A species can form within the

range of a parent speciesrange of a parent species Sympatric speciationSympatric speciation

SpeciationSpeciation

Adapted to heatthrough lightweightfur and long ears, legs, and nose, whichgive off more heat.

Adapted to coldthrough heavierfur, short ears,short legs, shortnose. White furmatches snowfor camouflage.

Gray Fox

Arctic Fox

Different environmentalconditions lead to differentselective pressures and evolutioninto two different species.

Spreadsnorthwardandsouthwardandseparates

Southernpopulation

Northernpopulation

Early foxpopulation

SpeciationSpeciation► Two species arise from one: As a population of organisms Two species arise from one: As a population of organisms

exploits new niches they become reproductively isolated from exploits new niches they become reproductively isolated from the parent population leading to adaptive radiationthe parent population leading to adaptive radiation Requires Reproductive isolation: Requires Reproductive isolation: Any heritable feature of body, form, Any heritable feature of body, form,

functioning, or behavior that prevents breeding between one or more functioning, or behavior that prevents breeding between one or more genetically divergent populationsgenetically divergent populations

► Geographic: Physically separatedGeographic: Physically separated► Temporal: Mate at different timesTemporal: Mate at different times► Behavioral: Bird calls / mating ritualsBehavioral: Bird calls / mating rituals► Anatomical: Picture a mouse and an elephant hooking upAnatomical: Picture a mouse and an elephant hooking up► Genetic Inviability: MulesGenetic Inviability: Mules

► AllopatricAllopatric Speciation that occurs when 2 or more populations of a species Speciation that occurs when 2 or more populations of a species

are geographically isolated from one another are geographically isolated from one another The allele frequencies in these populations changeThe allele frequencies in these populations change Members become so different that that can no no longer Members become so different that that can no no longer

interbreedinterbreed See See animationanimation

► SympatricSympatric Populations evolve with overlapping rangesPopulations evolve with overlapping ranges Behavioral barrier or hybridization or polyploidyBehavioral barrier or hybridization or polyploidy

The Case of the The Case of the Road-Killed SnailsRoad-Killed Snails

► Study of neighboring populations of Study of neighboring populations of snailssnails

► Genetic variation is greater between Genetic variation is greater between populations living on opposite sides populations living on opposite sides of the streetof the street

Color -

3 alleles of a gene

Allopatric SpeciationAllopatric Speciation

► Physical barrier Physical barrier

prevents gene prevents gene

flow between flow between

populations of a populations of a

speciesspecies Archipelago Archipelago

hotbed of hotbed of

speciationspeciation

Island BiogeographyIsland Biogeography

Adaptive Radiation•Evolution of new speciesfrom a common ancestral stock•Taking advantage of opportunity•Result of selective pressure reducing competition

Pre-Zygotic IsolationPre-Zygotic Isolation

► Mating or zygote formation is blockedMating or zygote formation is blocked Temporal IsolationTemporal Isolation

Behavioral IsolationBehavioral Isolation

Mechanical IsolationMechanical Isolation

Ecological IsolationEcological Isolation

Gamete MortalityGamete Mortality

Temporal Isolation in Apple Temporal Isolation in Apple MaggotsMaggots

Fig. 18.10, p. 290

Post-Zygotic IsolationPost-Zygotic Isolation

► Hybrids don’t workHybrids don’t work Zygotic mortality - Egg is fertilized but Zygotic mortality - Egg is fertilized but

zygote or embryo dieszygote or embryo dies

Hybrid inviability - First generation hybrid Hybrid inviability - First generation hybrid

forms but shows low fitnessforms but shows low fitness

Hybrid infertility - Hybrid is fully or Hybrid infertility - Hybrid is fully or

partially sterilepartially sterile

Extinctions - End of The LineExtinctions - End of The Line► Background extinctionBackground extinction

Local changing conditionsLocal changing conditions

Role of Humans?Role of Humans?

► Mass extinctionMass extinction Catastrophic global eventCatastrophic global event

Temperature changesTemperature changes

AsteroidsAsteroids

► Mass extinctionsMass extinctions Reduce competitionReduce competition

Open niches to exploitation by new speciesOpen niches to exploitation by new species

Leads to adaptive radiationLeads to adaptive radiation

Ordovician: 50% of animal families,

Devonian: 30% of animal families,

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

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

Cretaceous: up to 80% of ruling reptiles (dinosaurs); many marine species including manyforaminiferans and mollusks.

Current extinction crisis causedby human activities.

Species and families experiencing mass extinction

Bar width represents relative number of living species

Extinction

Millions ofyears ago

PeriodEra

Paleo

zoic

Meso

zoic

Cen

ozo

ic

Quaternary

Tertiary

Cretaceous

Jurassic

Triassic

Permian

Carboniferous

Devonian

Silurian

Ordovician

Cambrian

Today

65

180

250

345

500Extinction

Extinction

Extinction

Extinction

Extinction

ExtinctionExtinction► The ultimate fate of all species just as death is The ultimate fate of all species just as death is

for all individual organismsfor all individual organisms► 99.9% of all the species that have ever existed 99.9% of all the species that have ever existed

are now extinctare now extinct To a very close approximation, all species are To a very close approximation, all species are

extinctextinct► Background vs. Mass ExtinctionBackground vs. Mass Extinction

Low rate vs. 25-90% of totalLow rate vs. 25-90% of total Five great mass extinctions in which numerous new Five great mass extinctions in which numerous new

species (including mammals) evolved to fill new or species (including mammals) evolved to fill new or vacated niches in changed environmentsvacated niches in changed environments

10 million years or more for adaptive radiations to 10 million years or more for adaptive radiations to rebuild biological diversity following a mass rebuild biological diversity following a mass extinctionextinction

Extinction in the context of Extinction in the context of EvolutionEvolution

► If the environment changes rapidly andIf the environment changes rapidly and►The species living in these The species living in these

environments do not already possess environments do not already possess genes which enable survival in the face genes which enable survival in the face of such change andof such change and

►Random mutations do not accumulate Random mutations do not accumulate quickly enough thenquickly enough then

►All members of the unlucky species may All members of the unlucky species may diedie

BiodiversityBiodiversity► Speciation – Extinction=BiodiversitySpeciation – Extinction=Biodiversity► Humans major force in the premature extinction of Humans major force in the premature extinction of

species. Extinction rate increased by 100-1000 times species. Extinction rate increased by 100-1000 times the natural background rate. the natural background rate.

► As we grow in population over next 50 years, we are As we grow in population over next 50 years, we are expected to take over more of the earth’s surface and expected to take over more of the earth’s surface and productivity. This may cause the premature productivity. This may cause the premature extinction of up to a QUARTER of the earth’s current extinction of up to a QUARTER of the earth’s current species and constitute a SIXTH mass extinction species and constitute a SIXTH mass extinction Genetic engineering won’t solve this problemGenetic engineering won’t solve this problem Only takes existing genes and moves them aroundOnly takes existing genes and moves them around

► Know why this is so important and what we Know why this is so important and what we are losing as it disappears….are losing as it disappears….

And NUH is the letter I use to spell Nutches,Who live in small caves, known as Niches, for hutches.These Nutches have troubles, the biggest of which isThe fact there are many more Nutches than Niches.Each Nutch in a Nich knows that some other NutchWould like to move into his Nich very much.So each Nutch in a Nich has to watch that small NichOr Nutches who haven't got Niches will snitch.

-On Beyond Zebra (1955)Dr. Seuss

NichesNiches► A species functional role in an ecosystemA species functional role in an ecosystem► Involves everything that affects its survival and reproductionInvolves everything that affects its survival and reproduction

Includes range of tolerance of all abiotic factorsIncludes range of tolerance of all abiotic factors Trophic characteristicsTrophic characteristics How it interacts with biotic and abiotic factorsHow it interacts with biotic and abiotic factors Role it plays in energy flow and matter cyclingRole it plays in energy flow and matter cycling

► Generalist vs. SpecialistGeneralist vs. Specialist Lives many different places, eat many foods, tolerate a wide Lives many different places, eat many foods, tolerate a wide

range of conditions vs few, few, intolerant…range of conditions vs few, few, intolerant… Which strategy is better in a stable environment (K-Selected) Which strategy is better in a stable environment (K-Selected)

vs unstable (r-Selected)?vs unstable (r-Selected)?► Fundamental NicheFundamental Niche

Full potential range of physical chemical and biological Full potential range of physical chemical and biological conditions and resources it could theoretically use if there conditions and resources it could theoretically use if there was no direct competition from other specieswas no direct competition from other species

► Realized NicheRealized Niche Part of its niche actually occupied Part of its niche actually occupied

Niche: an organism’s role in the environment•Which has a better chance of survival specialist or generalist? Why?•What occurs when the niches of two species overlap?

Region of niche overlap

Generalist specieswith a broad nicheSpecialist species

with a narrow nicheNiche

breadth

Nicheseparation

Num

ber of individuals

Resource use

CompetitionCompetition

► Competitive ExclusionCompetitive Exclusion Gause’s Paramecium Gause’s Paramecium

ExperimentExperiment Superior competitor drives Superior competitor drives

inferior competitor to local inferior competitor to local extinctionextinction

► Character DisplacementCharacter Displacement Result of disruptive Result of disruptive

selection. New adaptations selection. New adaptations evolve decreasing niche evolve decreasing niche overlapoverlap

► Resource PartitioningResource Partitioning Competitors take advantage Competitors take advantage

of resources where of resources where competition is lowest.competition is lowest.

Competition Shrinks NichesCompetition Shrinks Niches

Barnacle Bill The ExampleBarnacle Bill The Example

Competition and Community Competition and Community DiversityDiversity

•Species evolve to minimize competition and niche overlap

•Results in a diverse matrix of differing species within a community

Interactions Between SpeciesInteractions Between Species

Type of Symbiosis Species A Species B

Predation + -

Competition - -

Mutualism + +

Parasitism + -

Commensalism + 0

Name the symbiosis!Name the symbiosis!

► Wolf/DeerWolf/Deer► Termite/Gut Termite/Gut

ProtozoaProtozoa► Cattle Cattle

Egret/CattleEgret/Cattle► Ants/Acacia TreeAnts/Acacia Tree► Tapeworm/DogTapeworm/Dog► Leaf Cutter Leaf Cutter

Ants/FungiAnts/Fungi

► Clover/Root Clover/Root NodulesNodules

► Remora/SharkRemora/Shark► Clown Clown

Fish/AnemoneFish/Anemone► Lion/AntelopeLion/Antelope► Moss/FernMoss/Fern► Tree/Bird NestTree/Bird Nest

Acorns and Lyme DiseaseAcorns and Lyme Disease

►What are the connections in the food What are the connections in the food web?web?

►How were they worked out?How were they worked out?►Design an experiment to test one or Design an experiment to test one or

more of these observationsmore of these observations What is your hypothesis?What is your hypothesis? What procedures would you use?What procedures would you use?

Integrated Pest ManagementIntegrated Pest Management

► Function is to reduce not Function is to reduce not eliminate pesteliminate pest

► Mimics NatureMimics Nature Requires a deep Requires a deep

understanding of the pests understanding of the pests natural biologynatural biology

► Niche an HabitatNiche an Habitat► Predators and CompetitorsPredators and Competitors► Reproductive Life CycleReproductive Life Cycle

► Judicial use of pesticidesJudicial use of pesticides► Emphasizes natural controlsEmphasizes natural controls

Introduce Introduce predators/parasitespredators/parasites

► Ladybugs/AphidsLadybugs/Aphids Modify environmentModify environment Interrupt life cycleInterrupt life cycle

What about the Gypsy Moths?!?

Let’s get rid of the mice!?Let’s get rid of the mice!?

IPM for TickIPM for Tick

► Life cycle: Larva-nymph-adultLife cycle: Larva-nymph-adult Hormone disruptorsHormone disruptors Sterilizing chemicalsSterilizing chemicals

► Preferred habitatPreferred habitat Cool, moist, tall grass/brushCool, moist, tall grass/brush

► Hosts: Mouse, deerHosts: Mouse, deer Inoculate against Lyme bacteriaInoculate against Lyme bacteria Introduce a predatorIntroduce a predator Lengthen Deer seasonLengthen Deer season

► PesticidesPesticides Time, amount and placementTime, amount and placement Minimize amount usedMinimize amount used

What’s Happening to the Otters?

Importance of SpeciesImportance of Species

►Keystone SpeciesKeystone Species►Indicator SpeciesIndicator Species►Invasive/Alien SpeciesInvasive/Alien Species►Endangered SpeciesEndangered Species

Online Summary 1 Online Summary 2

Ecological SuccessionEcological Succession

► Observe And Explain (STELLA)Observe And Explain (STELLA)

► Ecological SuccessionEcological Succession: The slow process of change in an ecosystem where : The slow process of change in an ecosystem where

one community is replaced by another community until a stable community one community is replaced by another community until a stable community

(i.e. climax community) is established over a period of time. (i.e. climax community) is established over a period of time.

► Pioneer speciesPioneer species: a species which first colonizes previously uncolonized land : a species which first colonizes previously uncolonized land

These species are able to survive harsh conditions and lead to soil formation.These species are able to survive harsh conditions and lead to soil formation.

► FacilitationFacilitation: Changes in the environment that make it easier of new species : Changes in the environment that make it easier of new species

to colonize. to colonize.

Pioneer species thicken the soil which makes it easier for larger plants to Pioneer species thicken the soil which makes it easier for larger plants to

survive.survive.

► CompetitionCompetition: (Inhibition) When 2 or more species try to get the same : (Inhibition) When 2 or more species try to get the same

resources. resources.

Taller plants get more sunlight than shorter plantsTaller plants get more sunlight than shorter plants

Animation of Primary SuccessionAnimation of Primary Succession

► Tolerance:Tolerance: When 2 species tolerate each other; They Coexist due to When 2 species tolerate each other; They Coexist due to

resource partitioningresource partitioning

► Climax communityClimax community: A stage in ecological development in which a : A stage in ecological development in which a

community of plants is stable and mature. community of plants is stable and mature.

Types of SuccessionTypes of Succession

•Primary succession:

Succession in an area

where no life or soil

exists

Soil Formation

Types of SuccessionTypes of Succession

Secondary SuccessionSecondary Succession

Fig. 48.24, p. 873

•Secondary succession: Succession in an area following a

disturbance where soil exists ( Bog Succession)