Community Ecology, Community Ecology, Population Ecology, and Population Ecology, and

SustainabilitySustainability

Chapter 6Chapter 6

Why Should We Care about the Why Should We Care about the American Alligator?American Alligator?

OverhuntedOverhunted

NichesNiches

Ecosystem servicesEcosystem services

Keystone speciesKeystone species

Endangered and threatened speciesEndangered and threatened species

Alligator farmsAlligator farms

Fig. 6-1, p. 108

Why Should We Care about Why Should We Care about the American Alligator?the American Alligator?

Fig. 6-1, p. 108

Community Structure and Community Structure and Species DiversitySpecies Diversity

Physical appearancePhysical appearance

Edge effectsEdge effects

Species diversity or richnessSpecies diversity or richness

Species abundance or evennessSpecies abundance or evenness

Niche structureNiche structure

Fig. 6-2, p. 110

Natural Capital: Types, Sizes, and Natural Capital: Types, Sizes, and Stratification of Terrestrial PlantsStratification of Terrestrial Plants

Tropical rain forest

Coniferous forest

Deciduous forest

Thorn forest

Thorn scrub

Tall-grass prairie

Short-grass prairie

Desert scrub

Species Diversity and Ecological Species Diversity and Ecological StabilityStability

Many different species provide ecological stabilityMany different species provide ecological stability

Some exceptionsSome exceptions

Minimum threshold of species diversityMinimum threshold of species diversity

Many unknownsMany unknowns

Net primary productivity (NPP)Net primary productivity (NPP)

Essential and nonessential speciesEssential and nonessential species

Types of SpeciesTypes of Species

NativeNative

Nonnative (invasive or alien)Nonnative (invasive or alien)

IndicatorIndicator

KeystoneKeystone

FoundationFoundation

Indicator SpeciesIndicator Species

Provide early warningsProvide early warnings

Indicator of water qualityIndicator of water quality

Birds as environmental indicatorsBirds as environmental indicators

ButterfliesButterflies

AmphibiansAmphibians

Amphibians as Indicator SpeciesAmphibians as Indicator Species

Environmentally sensitive life cycleEnvironmentally sensitive life cycle

Vulnerable eggs and skinVulnerable eggs and skin

Declining populationsDeclining populations

sperm

Eggs

Sexualreproduction

Fertilized eggdevelopment Organ formation

Egg hatches

Tadpole

Tadpole develops into frog

Young frogAdult frog(3 years)

Fig. 6-3, p. 112

Life Cycle of a FrogLife Cycle of a Frog

Possible Causes of Declining Possible Causes of Declining Amphibian PopulationsAmphibian Populations

Habitat loss and fragmentationHabitat loss and fragmentation

Prolonged droughtProlonged drought

PollutionPollution

Increases in ultraviolet radiationIncreases in ultraviolet radiation

ParasitesParasites

OverhuntingOverhunting

DiseaseDisease

Nonnative speciesNonnative species

Why Should We Care about Why Should We Care about Vanishing Amphibians?Vanishing Amphibians?

Indicator of environmental healthIndicator of environmental health

Important ecological roles of amphibiansImportant ecological roles of amphibians

Genetic storehouse for pharmaceuticalsGenetic storehouse for pharmaceuticals

Keystone SpeciesKeystone Species

What is a keystone?What is a keystone?

Keystone species play critical ecological rolesKeystone species play critical ecological roles

PollinationPollination

Top predatorsTop predators

Dung beetlesDung beetles

SharksSharks

Why are Sharks Important?Why are Sharks Important? Ecological roles of sharksEcological roles of sharks

Shark misconceptionsShark misconceptions

Human deaths and injuriesHuman deaths and injuries

Lightning is more dangerous than sharksLightning is more dangerous than sharks

Shark hunting and shark finsShark hunting and shark fins

Mercury contaminationMercury contamination

Medical researchMedical research

Declining populationsDeclining populations

Hunting bans: effective?Hunting bans: effective?

Foundation SpeciesFoundation Species

Relationship to keystones speciesRelationship to keystones species

Play important roles in shaping communitiesPlay important roles in shaping communities

ElephantsElephants

Contributions of bats and birdsContributions of bats and birds

Species Interactions Species Interactions

Interspecific competitionInterspecific competition

PredationPredation

ParasitismParasitism

MutualismMutualism

CommensalismCommensalism

Species Interactions: CompetitionSpecies Interactions: Competition

Interspecific CompetitionInterspecific Competition

Fundamental nichesFundamental niches

Fighting for limited resourcesFighting for limited resources

Competition from humansCompetition from humans

Reducing or Avoiding CompetitionReducing or Avoiding Competition

Resource partitioningResource partitioning

Role of natural selectionRole of natural selection

Specialization and sharing of resourcesSpecialization and sharing of resources

Resource partitioning of warblersResource partitioning of warblers

Fig. 6-4, p. 114

Nu

mb

er o

f in

div

idu

als

Nu

mb

er o

f in

div

idu

als

Resource use

Resource use

Species 1 Species 2

Regionof

niche overlap

Species 1 Species 2

Resource Partitioning and Niche Resource Partitioning and Niche SpecializationSpecialization

Fig. 6-5, p. 115

Resource Partitioning of Warbler Resource Partitioning of Warbler SpeciesSpecies

Predator and Prey InteractionsPredator and Prey Interactions

Carnivores and herbivoresCarnivores and herbivores

PredatorsPredators

PreyPrey

Natural selection and prey populationsNatural selection and prey populations

How Do Predators Increase Their How Do Predators Increase Their Chances of Getting a Meal?Chances of Getting a Meal?

SpeedSpeed

SensesSenses

Camouflage and ambushCamouflage and ambush

Chemical warfare (venom)Chemical warfare (venom)

Avoiding and Defending Against Avoiding and Defending Against PredatorsPredators

EscapeEscape SensesSenses ArmorArmor CamouflageCamouflage Chemical warfareChemical warfare Warning colorationWarning coloration MimicryMimicry Behavior strategiesBehavior strategies Safety in numbersSafety in numbers

Span worm Bombardier beetle

Viceroy butterfly mimicsmonarch butterfly

Foul-tasting monarch butterfly

Poison dart frog When touched, the snake caterpillar changes shape to look like the head of a snake

Wandering leaf insect

Hind wings of io mothresemble eyes of a much larger animal

Fig. 6-6, p. 116

How Species Avoid PredatorsHow Species Avoid Predators

ParasitesParasites

ParasitismParasitism

HostsHosts

Inside or outside of hostsInside or outside of hosts

Harmful effects on hostsHarmful effects on hosts

Important ecological roles of parasitesImportant ecological roles of parasites

MutualismMutualism

Both species benefitBoth species benefit

PollinationPollination

Benefits include nutrition and protectionBenefits include nutrition and protection

MycorrhizaeMycorrhizae

Gut inhabitant mutualismGut inhabitant mutualism

Oxpeckers and black rhinoceros Clown fish and sea anemone

Lack of mycorrhizae fungi on juniper seedlings in sterilized soil Fig. 6-7, p. 117

Examples of MutualismExamples of Mutualism

© 2006 Brooks/Cole - Thomson

Mycorrhizae fungi on juniper seedlings in normal soil

CommensalismCommensalism

Species interaction that benefits one Species interaction that benefits one and has little or no effect on the otherand has little or no effect on the other

Example: Small plants growing in Example: Small plants growing in shade of larger plantsshade of larger plants

EpiphytesEpiphytes

Bromeliad CommensalismBromeliad Commensalism

Fig. 6-8, p. 118

Ecological Succession: Ecological Succession: Communities in TransitionCommunities in Transition

What is ecological succession?What is ecological succession?

Primary successionPrimary succession

Secondary successionSecondary succession

Fig. 6-9, p. 119

Time

Small herbsand shrubs

Heath mat

Jack pine,black spruce,

and aspen

Balsam fir, paper birch, and white spruce climax

community

Exposedrocks

Lichensand mosses

Primary Ecological SuccessionPrimary Ecological Succession

Fig. 6-10, p. 120

Annualweeds

Perennialweeds and

grasses

Shrubs and pine seedlings

Young pine forest with developing understory

of oak and hickory trees

Mature oak-hickory forest

Secondary Ecological SuccessionSecondary Ecological Succession

Time

How Predictable is Succession?How Predictable is Succession?

Climax community conceptClimax community concept

““Balance of nature”Balance of nature”

New views of equilibrium in natureNew views of equilibrium in nature

Unpredictable successionUnpredictable succession

Natural strugglesNatural struggles

Population Dynamics: Factors Population Dynamics: Factors Affecting Population SizeAffecting Population Size

Population change = (births + immigration) Population change = (births + immigration) – (deaths + emigration)– (deaths + emigration)

Age structure (stages)Age structure (stages)

Age and population stabilityAge and population stability

Limits on Population GrowthLimits on Population Growth

Biotic potentialBiotic potential

Intrinsic rate of increase (Intrinsic rate of increase (rr) )

No indefinite population growthNo indefinite population growth

Environmental resistanceEnvironmental resistance

Carrying capacity (Carrying capacity (KK))

Exponential and Logistic Exponential and Logistic Population GrowthPopulation Growth

Resources control population growthResources control population growth

Exponential growthExponential growth

Logistic growthLogistic growth

Fig. 6-11, p. 121

Carrying capacity (K)

Environmentalresistance

Bioticpotential

Exponentialgrowth

Population Growth CurvesPopulation Growth Curves

Time (t)

Po

pu

lati

on

siz

e (N

)

Fig. 6-12, p. 121

Logistic Growth of Sheep PopulationLogistic Growth of Sheep Population

Overshoot Carrying Capacity

Year

Nu

mb

er o

f sh

eep

(m

illi

on

s)2.0

1.5

1.0

.5

1800 1825 1850 1875 1900 1925

When Population Size Exceeds When Population Size Exceeds Carrying CapacityCarrying Capacity

Switch to new resources, move or dieSwitch to new resources, move or die

OvershootsOvershoots

Reproductive time lagReproductive time lag

Population dieback or crashPopulation dieback or crash

Famines among humansFamines among humans

Factors controlling human carrying capacityFactors controlling human carrying capacity

Exponential Growth, Overshoot and Exponential Growth, Overshoot and Population Crash of ReindeerPopulation Crash of Reindeer

Fig. 6-13, p. 122

PopulationOvershootsCarrying Capacity

Populationcrashes

Carrying capacity

Year

Nu

mb

er o

f sh

eep

(m

illi

on

s) 2,000

1,500

1,000

500

01910 1920 1930 1940 1950

Reproductive PatternsReproductive Patterns

r-selected speciesr-selected species

Opportunists (mostly r-selected)Opportunists (mostly r-selected)

Environmental impacts on opportunistsEnvironmental impacts on opportunists

K-selected species (competitors)K-selected species (competitors)

Intermediate and variable reproductive patternsIntermediate and variable reproductive patterns

Carrying capacity

K species;experienceK selection

r species;experiencer selection

K

Fig. 6-14, p. 122

Positions of r-selected and K-selected Positions of r-selected and K-selected Species on Population Growth CurveSpecies on Population Growth Curve

Number of individuals

Time

Nu

mb

er o

f in

div

idu

als

Fig. 6-15, p. 123

r-selected Opportunists and K-selected Speciesr-selected Opportunists and K-selected Species

r-Selected Species

CockroachDandelion

Many small offspring

Little or no parental care and protection of offspring

Early reproductive age

Most offspring die before reaching reproductive age

Small adults

Adapted to unstable climate and environmental conditions

High population growth rate (r)

Population size fluctuates wildly above and below carrying capacity (K)

Generalist niche

Low ability to compete

Early successional species

Fig. 6-15a, p. 123

r-selected r-selected Opportunists Opportunists

and K-selected and K-selected SpeciesSpecies

Fewer, larger offspring

High parental care and protection of offspring

Later reproductive age

Most offspring survive to reproductive age

Larger adults

Adapted to stable climate and environmental conditions

Lower population growth rate (r)

Population size fairly stable and usually close to carrying capacity (K)

Specialist niche

High ability to compete

Late successional species

ElephantSaguaro

K-Selected Species

Fig. 6-15b, p. 123

r-selected r-selected Opportunists Opportunists

and K-selected and K-selected SpeciesSpecies

Fig. 6-16, p. 124

Property Natural Systems Human-DominatedSystems

Complexity

Energy source

Waste production

Nutrients

Net primaryproductivity

Biologically diverse

Renewable solarenergy

Little, if any

Recycled

Shared among manyspecies

Biologicallysimplified

Mostly nonrenewablefossil fuel energy

High

Often lost of wasted

Used, destroyed, ordegraded to supporthuman activities

Characteristics of Natural and Characteristics of Natural and Human-Dominated SystemsHuman-Dominated Systems

Fig. 6-17, p. 125

Reduction of biodiversity

Increasing use of the earth'snet primary productivity

Increasing genetic resistanceof pest species and diseasecausing bacteria

Elimination of many naturalpredators

Deliberate or accidentalintroduction of potentiallyharmful species intocommunities

Using some renewableresources faster than they canbe replenished

Interfering with the earth'schemical cycling and energyflow processes

Relying mostly on pollutingfossil fuels

Human Impacts on EcosystemsHuman Impacts on EcosystemsNatural Capital Degradation

Altering Nature to Meet Our Needs

Fig. 6-18, p. 126

Four Principles of SustainabilityFour Principles of Sustainability

PRINCIPLESOF

SUSTAINABILITY

Solar

Energy

Population

Control

Nutrient

Recycling Biodiv

ersi

ty

Runs on renewable solar energy.

Recycles nutrients and wastes. There is little waste in nature.

Uses biodiversity to maintain itself and adapt to new environmental conditions.

Controls a species' population size and resource use by interactionswith its environment and other species.

Rely mostly on renewable solarenergy.

Prevent and reducepollution and recycleand reuse resources.

Preserve biodiversity by protecting ecosystemservices and preventing premature extinction of species.

Reduce births and wasteful resource use to prevent environmental overload and depletion and degradation of resources.

Fig. 6-19, p. 126

Solutions:Implicationsof the Principlesof Sustainability

Solutions

Principles of Sustainability

How Nature Works Lessons for Us

Lessons from NatureLessons from Nature We are dependent on the Earth and SunWe are dependent on the Earth and Sun

Everything is interdependent with everything elseEverything is interdependent with everything else

We can never do just one thingWe can never do just one thing

Earth’s natural capital must be sustainedEarth’s natural capital must be sustained

Precautionary PrinciplePrecautionary Principle

Prevention is better than curePrevention is better than cure

Risks must be takenRisks must be taken