chp 7 miller

8/14/2019 Chp 7 Miller

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Chapter 7Chapter 7

Community EcologyCommunity Ecology


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Chapter Overview QuestionsChapter Overview Questions

What determines the number of species in aWhat determines the number of species in acommunity?community?How can we classify species according toHow can we classify species according to

their roles in a community?their roles in a community?How do species interact with one another?How do species interact with one another?How do communities respond to changes inHow do communities respond to changes inenvironmental conditions?environmental conditions?Does high species biodiversity increase theDoes high species biodiversity increase thestability and sustainability of a community?stability and sustainability of a community?


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Updates OnlineUpdates Online

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

InfoTrac: California's wild crusade. Virginia Morell.InfoTrac: California's wild crusade. Virginia Morell. National National

Geographic Geographic , Feb 2006 v209 i2 p80(16)., Feb 2006 v209 i2 p80(16).InfoTrac: Traveling green. Carol Goodstein.InfoTrac: Traveling green. Carol Goodstein. Natural History Natural History ,,July-August 2006 v115 i6 p16(4) .July-August 2006 v115 i6 p16(4) .InfoTrac: Too hot to trot. Charlie Furness.InfoTrac: Too hot to trot. Charlie Furness. Geographical Geographical , May, May2006 v78 i5 p51(7).2006 v78 i5 p51(7).The Nature Conservancy: Jaguar Habitat and Center of The Nature Conservancy: Jaguar Habitat and Center of Maya Civilization Protected in Historic Land DealMaya Civilization Protected in Historic Land DealNational Geographic NewsNational Geographic News : Conservationists Name Nine: Conservationists Name NineNew "Biodiversity Hotspots"New "Biodiversity Hotspots"


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Video: WhalingVideo: Whaling

This video clip is available in CNN TodayThis video clip is available in CNN TodayVideos for Environmental Science, 2004,Videos for Environmental Science, 2004,Volume VII. Instructors, contact your localVolume VII. Instructors, contact your local

sales representative to order this volume,sales representative to order this volume,while supplies last.while supplies last.


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

American Alligator?American Alligator?

Hunters wiped outHunters wiped out

population to thepopulation to thepoint of near point of near extinction.extinction.

Alligators haveAlligators haveimportant ecologicalimportant ecologicalrole.role.

Figure 7-1Figure 7-1


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

American Alligator?American Alligator?Dig deep depressions (gator holes).Dig deep depressions (gator holes).

Hold water during dry spells, serve as refugesHold water during dry spells, serve as refugesfor 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.Alligators are a keystone species:Alligators are a keystone species:

Help maintain the structure and function of theHelp maintain the structure and function of thecommunities where it is found.communities where it is found.


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COMMUNITY STRUCTURE ANDCOMMUNITY STRUCTURE ANDSPECIES DIVERSITYSPECIES DIVERSITY

Biological communities differ in their structureBiological communities differ in their structure

and physical appearance.and physical appearance. Figure 7-2Figure 7-2


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Short-grassprairie

Desertscrub

Tall-grassprairie

Thornscrub

Thornforest

Deciduousforest

Coniferousforest

Tropicalrain forest


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Species Diversity and NicheSpecies Diversity and NicheStructure: Different Species PlayingStructure: Different Species Playing

Different RolesDifferent Roles

Biological communities differ in the types andBiological communities differ in the types and

numbers of species they contain and thenumbers of species they contain and theecological roles those species play.ecological roles those species play.

Species diversity Species diversity : the number of different: the number of different

species it contains (species it contains ( species richnessspecies richness ) combined) combinedwith the abundance of individuals within each of with the abundance of individuals within each of those species (those species ( species evennessspecies evenness ).).


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Species Diversity and Niche StructureSpecies Diversity and Niche Structure

Niche structure: how many potentialNiche structure: how many potentialecological niches occur, how they resembleecological niches occur, how they resembleor differ, and how the species occupyingor differ, and how the species occupying

different niches interact.different niches interact.Geographic location: species diversity isGeographic location: species diversity ishighest in the tropics and declines as wehighest in the tropics and declines as we

move from the equator toward the poles.move from the equator toward the poles.


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TYPES OF SPECIESTYPES OF SPECIES

Native, nonnative, indicator, keystone, andNative, nonnative, indicator, keystone, andfoundation species play different ecologicalfoundation species play different ecologicalroles in communities.roles in communities.

Native: those that normally live and thrive in aNative: those that normally live and thrive in aparticular community.particular community.Nonnative species: those that migrate,Nonnative species: those that migrate,deliberately or accidentally introduced into adeliberately or accidentally introduced into acommunity.community.


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

MacArthur and Wilson proposed the speciesMacArthur and Wilson proposed the speciesequilibrium model or theory of islandequilibrium model or theory of islandbiogeography in the 1960s.biogeography in the 1960s.Model projects that at some point the rates of Model projects that at some point the rates of immigration and extinction should reach animmigration and extinction should reach an

equilibrium based on:equilibrium based on:Island sizeIsland sizeDistance to nearest mainlandDistance to nearest mainland


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Indicator Species:Indicator Species:Biological Smoke AlarmsBiological Smoke Alarms

Species that serve as early warnings of Species that serve as early warnings of damage to a community or an ecosystem.damage to a community or an ecosystem.

Presence or absence of trout species becausePresence or absence of trout species becausethey are sensitive to temperature and oxygenthey are sensitive to temperature and oxygenlevels.levels.


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Keystone Species: Major PlayersKeystone Species: Major Players

Keystone species help determine the typesKeystone species help determine the typesand numbers of other species in aand numbers of other species in acommunity thereby helping to sustain it.community thereby helping to sustain it.

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


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Foundation Species:Foundation Species:Other Major PlayersOther Major Players

Expansion of keystone species category.Expansion of keystone species category.Foundation species can create and enhanceFoundation species can create and enhancehabitats that can benefit other species in ahabitats that can benefit other species in acommunity.community.

Elephants push over, break, or uproot trees,Elephants push over, break, or uproot trees,creating forest openings promoting grass growthcreating forest openings promoting grass growthfor other species to utilize.for other species to utilize.


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

Frogs serve as indicator species becauseFrogs serve as indicator species becausedifferent parts of their life cycles can be easilydifferent parts of their life cycles can be easilydisturbed.disturbed. Figure 7-3Figure 7-3


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Young frogAdult frog(3 years)

Sperm

SexualReproduction

Eggs Fertilized eggdevelopment Organ formation

Egg hatches

Tadpole

Tadpole developsinto frog


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

Habitat loss and fragmentation.Habitat loss and fragmentation.Prolonged drought.Prolonged drought.Pollution.Pollution.Increases in ultraviolet radiation.Increases in ultraviolet radiation.Parasites.Parasites.

Viral and Fungal diseases.Viral and Fungal diseases.Overhunting.Overhunting.Natural immigration or deliberate introductionNatural immigration or deliberate introduction

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


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Video: Frogs GaloreVideo: Frogs Galore

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

PLAYVIDEO
http://videos/frogs_galore.htmlhttp://videos/frogs_galore.htmlhttp://videos/frogs_galore.html


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How Would You Vote?How Would You Vote?

To conduct an instant in-class survey using a classroom responseTo conduct an instant in-class survey using a classroom responsesystem, access JoinIn Clicker Content from the PowerLecture mainsystem, access JoinIn Clicker Content from the PowerLecture mainmenu for Living in the Environment.menu for Living in the Environment.

Do we have an ethical obligation to protect sharkDo we have an ethical obligation to protect sharkspecies from premature extinction and treat themspecies from premature extinction and treat themhumanely?humanely?

a. No. It's impractical to force international laws ona. No. It's impractical to force international laws on

individual fishermen that are simply trying to feed their individual fishermen that are simply trying to feed their families with the fishing techniques that they have.families with the fishing techniques that they have.b. Yes. Sharks are an important part of marineb. Yes. Sharks are an important part of marineecosystems. They must be protected and, like all animals,ecosystems. They must be protected and, like all animals,

they should be humanely treated.they should be humanely treated.


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SPECIES INTERACTIONS:SPECIES INTERACTIONS:

COMPETITION AND PREDATIONCOMPETITION AND PREDATIONSpecies can interact through competition,Species can interact through competition,

predation, parasitism, mutualism, andpredation, parasitism, mutualism, andcommensalism.commensalism.Some species evolve adaptations thatSome species evolve adaptations thatallow them to reduce or avoid competitionallow them to reduce or avoid competitionfor resources with other species (resourcefor resources with other species (resourcepartitioning).partitioning).


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Resource PartitioningResource Partitioning

Each species minimizesEach species minimizescompetition with the otherscompetition with the othersfor food by spending atfor food by spending atleast half its feeding timeleast half its feeding timein a distinct portion of thein a distinct portion of thespruce tree and byspruce tree and by

consuming somewhatconsuming somewhatdifferent insect species.different insect species.



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Niche SpecializationNiche Specialization

Niches becomeNiches becomeseparated toseparated toavoid competitionavoid competitionfor resources.for resources.



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Fig. 7-6, p. 150

Species 2Species 1

Numberofindividuals

Numberofindividuals

Species 2Species 1

Resource use

Resource use

Regionof

niche overlap


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SPECIES INTERACTIONS:SPECIES INTERACTIONS:COMPETITION AND PREDATIONCOMPETITION AND PREDATION

Species called predators feed on other Species called predators feed on other species called prey.species called prey.

Organisms use their senses their senses toOrganisms use their senses their senses tolocate objects and prey and to attractlocate objects and prey and to attractpollinators and mates.pollinators and mates.

Some predators are fast enough to catch their Some predators are fast enough to catch their prey, some hide and lie in wait, and someprey, some hide and lie in wait, and someinject chemicals to paralyze their prey.inject chemicals to paralyze their prey.


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PREDATIONPREDATION

Some prey escapeSome prey escapetheir predators or their predators or

have outer have outer protection, someprotection, someare camouflaged,are camouflaged,

and some useand some usechemicals to repelchemicals to repelpredators.predators.



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Fig. 7-8a, p. 153(a) Span worm


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Fig. 7-8b, p. 153(b) Wandering leaf insect


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Fig. 7-8c, p. 153(c) Bombardier beetle


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Fig. 7-8d, p. 153(d) Foul-tasting monarch butterfly


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Fig. 7-8e, p. 153

(e) Poison dart frog


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Fig. 7-8f, p. 153(f) Viceroy butterfly mimicsmonarch butterfly


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Fig. 7-8h, p. 153

(h) When touched, snakecaterpillar changes shapeto look like head of snake.


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SPECIES INTERACTIONS:SPECIES INTERACTIONS:PARASITISM, MUTUALISM, ANDPARASITISM, MUTUALISM, AND

COMMENSALIMCOMMENSALIMParasitism occurs when one species feedsParasitism occurs when one species feeds

on part of another organism.on part of another organism.In mutualism, two species interact in a wayIn mutualism, two species interact in a waythat benefits both.that benefits both.

Commensalism is an interaction that benefitsCommensalism is an interaction that benefitsone species but has little, if any, effect on theone species but has little, if any, effect on theother species.other species.


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Parasites: Sponging Off of OthersParasites: Sponging Off of Others

Although parasites can harm their hosts, theyAlthough parasites can harm their hosts, theycan promote community biodiversity.can promote community biodiversity.

Some parasites live in host (micororganisms,Some parasites live in host (micororganisms,

tapeworms).tapeworms).Some parasites live outside host (fleas, ticks,Some parasites live outside host (fleas, ticks,mistletoe plants, sea lampreys).mistletoe plants, sea lampreys).Some have little contact with host (dump-nestingSome have little contact with host (dump-nestingbirds like cowbirds, some duck species)birds like cowbirds, some duck species)


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Mutualism: Win-Win RelationshipMutualism: Win-Win Relationship

Two speciesTwo speciescan interact incan interact inways thatways thatbenefit both of benefit both of them.them.



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Fig. 7-9a, p. 154(a) Oxpeckers and black rhinoceros


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Fig. 7-9b, p. 154(b) Clownfish and sea anemone


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Fig. 7-9c, p. 154(c) Mycorrhizal fungi on juniper seedlingsin normal soil


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Fig. 7-9d, p. 154(d) Lack of mycorrhizal fungi on juniper seedlingsin sterilized soil


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Commensalism: Using without HarmingCommensalism: Using without Harming

Some speciesSome speciesinteract in a wayinteract in a waythat helps onethat helps onespecies but hasspecies but haslittle or no effectlittle or no effecton the other.on the other.



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ECOLOGICAL SUCCESSION:ECOLOGICAL SUCCESSION:COMMUNITIES IN TRANSITIONCOMMUNITIES IN TRANSITION

New environmental conditions allow oneNew environmental conditions allow onegroup of species in a community to replacegroup of species in a community to replaceother groups.other groups.Ecological successionEcological succession : the gradual change: the gradual changein species composition of a given areain species composition of a given area

Primary successionPrimary succession : the gradual establishment: the gradual establishment

of biotic communities in lifeless areas whereof biotic communities in lifeless areas wherethere is no soil or sediment.there is no soil or sediment.Secondary successionSecondary succession : series of communities: series of communitiesdevelop in places containing soil or sediment.develop in places containing soil or sediment.


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Primary Succession:Primary Succession:Starting from ScratchStarting from Scratch

PrimaryPrimarysuccessionsuccession

begins with anbegins with anessentiallyessentiallylifeless arelifeless arewhere there iswhere there isno soil in ano soil in aterrestrialterrestrialecosystemecosystem



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Fig. 7-11, p. 156

Exposedrocks

Lichensand mosses

S m a ll h e r b s a n d s h r u b s

H e a t h m a t J a c k p ine ,

b lac k s p ruc e ,

a n d a s p e n

Ba l s a m f ir,

pa per b irc h, and

w h i te s p ruc e

fore s t c o m m un i t y

T i m e


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Secondary Succession:Secondary Succession:Starting Over with Some HelpStarting Over with Some Help

SecondarySecondarysuccessionsuccession

begins in anbegins in anarea wherearea wherethe naturalthe naturalcommunitycommunityhas beenhas beendisturbed.disturbed.



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Fig. 7-12, p. 157

T i m e

A n n u a l

w e e d s

P e r e n n i a l

w e e d s a n d

g r a s s e s

S h ru b san d p in es ee d lin gs

Yo u n g p i n e fo r e s t

w i t h d e v e lo p i n g u n d e r s to r y

o f o a k

a n d h ic ko r y t r e e s

M a t u r e o a k- h ic k o

r y f o r e s t


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Can We Predict the Path of Can We Predict the Path of Succession, and is Nature inSuccession, and is Nature in

Balance?Balance?The course of succession cannot beThe course of succession cannot be

precisely predicted.precisely predicted.Previously thought that a stable climaxPreviously thought that a stable climaxcommunity will always be achieved.community will always be achieved.

Succession involves species competing for Succession involves species competing for enough light, nutrients and space which willenough light, nutrients and space which willinfluence its trajectory.influence its trajectory.


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ECOLOGICAL STABILITY ANDECOLOGICAL STABILITY ANDSUSTAINABILITYSUSTAINABILITY

Living systems maintain some degree of Living systems maintain some degree of stability through constant change in responsestability through constant change in responseto environmental conditions through:to environmental conditions through:

Inertia (persistence): the ability of a living systemInertia (persistence): the ability of a living systemto resist being disturbed or altered.to resist being disturbed or altered.Constancy: the ability of a living system to keepConstancy: the ability of a living system to keepits numbers within the limits imposed by availableits numbers within the limits imposed by availableresources.resources.Resilience: the ability of a living system toResilience: the ability of a living system tobounce back and repair damage after (a not toobounce back and repair damage after (a not toodrastic) disturbance.drastic) disturbance.


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ECOLOGICAL STABILITY ANDECOLOGICAL STABILITY AND

SUSTAINABILITYSUSTAINABILITYHaving many different species appears toHaving many different species appears toincrease the sustainability of manyincrease the sustainability of manycommunities.communities.Human activities are disrupting ecosystemHuman activities are disrupting ecosystemservices that support and sustain all life andservices that support and sustain all life and

all economies.all economies.

chp 7 miller

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