ecology of communities types of species interactions

Ecology of Ecology of CommunitiesCommunities

Types of Species Types of Species InteractionsInteractions

Species Species InteractionsInteractions

• Close Close interaction interaction between between species.species.– PredationPredation– ParasitismParasitism– CompetitionCompetition– MutualismMutualism– CommensalismCommensalism

Tuesday 9/5/06Tuesday 9/5/06Pages 397-402Pages 397-402Section 21-1Section 21-1

Which community is most Which community is most diverse? Why?diverse? Why?

PredationPredation• Predators Predators capture, kill, capture, kill, and consume and consume prey.prey.– Predators are Predators are adapted to adapted to role.role.

– Prey are Prey are adapted to adapted to survive survive predatorpredator

Which species determines the Which species determines the number of the other?number of the other?

Tuesday Tuesday 9/05/069/05/06

Pages 397-402Pages 397-402Section 21-1Section 21-1

PredationPredation

• MimicryMimicry– Prey evolve Prey evolve defenses defenses through through natural natural selection.selection.

– Coloration Coloration mimicsmimics poisonous poisonous organism.organism.

– Warning Warning colorationcoloration

Why is the western King Snake Why is the western King Snake not colored like the Arizona not colored like the Arizona

King Snake?King Snake?



• MimicryMimicry– Batesian mimicryBatesian mimicry

• One poisonous, one One poisonous, one notnot

– Mullerian mimicryMullerian mimicry• Both poisonousBoth poisonous

PredationPredation

• Plant - HerbivorePlant - Herbivore• Plants are Plants are defending against defending against herbivory.herbivory.– Thorns, spines, Thorns, spines, sticky hairs.sticky hairs.

– Secondary Secondary chemicalschemicals• NicotineNicotine• StrychnineStrychnine• DigitalisDigitalis• Poison oakPoison oak

What animal group is the What animal group is the plant trying to discourage?plant trying to discourage?



ParasitisParasitismm

• Parasite is Parasite is helped.helped.

• Host is harmed.Host is harmed.– EctoparsitesEctoparsites– EndoparasitesEndoparasites

Why does a parasite usually Why does a parasite usually not kill its host?not kill its host?



MutualismMutualism

• Both species Both species benefit.benefit.

• LichensLichens– 2 layers of fungi2 layers of fungi– Algae cells inside.Algae cells inside.– Algae is kept moistAlgae is kept moist– Fungi get food.Fungi get food.

Are mutualism relationships Are mutualism relationships species specific?species specific?

Modern Biology Modern Biology Pages 397-402Pages 397-402Section 21-1Section 21-1

CommensalismCommensalism

• One species One species benefits.benefits.

• One species is not One species is not effected.effected.– Lichens growing on Lichens growing on a tree limb.a tree limb.

– Cattle egrets and Cattle egrets and live stock.live stock.


CompetitiCompetitionon

• Results from Results from fundamental niche fundamental niche overlap.overlap.– Competitive Competitive exclusion.exclusion.

– When two species When two species directly compete, directly compete, one will go one will go extinct.extinct.

What, most likely, is being What, most likely, is being competed for in this study?competed for in this study?

Modern BiologyModern BiologyPages 397-402Pages 397-402Section 21-1Section 21-1


• Results from Results from fundamental niche fundamental niche overlap.overlap.– Character Character displacementdisplacement

– Competitors evolve Competitors evolve to different to different niches.niches.

How does the Barn Owl and Red Tail How does the Barn Owl and Red Tail Hawk demonstrate character Hawk demonstrate character

displacement?displacement?



• Results from Results from fundamental niche fundamental niche overlap.overlap.– Resource Resource partitioning.partitioning.

– Each competing Each competing species uses a species uses a portion of the portion of the resource.resource.

– Results in less Results in less competition between competition between species.species.

How does the Cape may Warbler How does the Cape may Warbler differ from the rest of the differ from the rest of the

warbler species?warbler species?



ReviewReview

• Fundamental Fundamental nicheniche– Full range of Full range of interactions interactions in ecosystem.in ecosystem.

– All potential All potential resourcesresources

– Theoretical Theoretical niche as if no niche as if no other other organisms organisms presentpresent

Why is the realized niche Why is the realized niche shown above smaller than the shown above smaller than the

fundamental niche?fundamental niche?

Modern Modern BiologyBiology

Pages 363-Pages 363-365365

Key Words:Key Words:Fundamental nicheFundamental niche

Realized nicheRealized niche

How is a How is a fundamental niche fundamental niche different from a different from a realized niche?realized niche?

• Modern BiologyModern Biology• Pages 371-372Pages 371-372Ecology of Ecology of

OrganismsOrganisms

• Realized nicheRealized niche– All resources All resources actually used.actually used.

– Competition with Competition with other organisms other organisms limits limits fundamental fundamental niche.niche.

– Something less Something less than the than the fundamental fundamental niche.niche. Which species out competes the other Which species out competes the other

species regarding niche?species regarding niche?

Properties of Properties of CommunitiesCommunities

Modern BiologyModern Biology Pages 397-402Pages 397-402Section 21-1Section 21-1

• Species Species richness.richness.– The total number The total number of species in an of species in an ecosystem.ecosystem.

Properties of Properties of CommunitiesCommunities


• Species Species diversity.diversity.– The total number The total number of species in an of species in an ecosystem.ecosystem.

– Also accounts for Also accounts for the number of the number of each species.each species.

Patterns of Patterns of Species Species RichnessRichness


• Closer to the Closer to the equator, the equator, the greater the greater the richness.richness.

• Reasons why:Reasons why:– Older communities Older communities in tropics.in tropics.

– Stable climateStable climate– More available More available energyenergy

SuccessionSuccession Modern BiologyModern Biology Pages 397-402Pages 397-402Section 21-1Section 21-1

• Gradual regrowth of Gradual regrowth of species after a species after a disruption.disruption.

• Two types of Two types of succession:succession:– Primary (starts with Primary (starts with pioneer species)pioneer species)

– Secondary (occurs Secondary (occurs after disruption)after disruption)• FireFire• FloodFlood• StormStorm• Human activityHuman activity• FarmingFarming

Primary Primary SuccessionSuccession


• Starts slow due to Starts slow due to lack of minerals.lack of minerals.– Pioneer species Pioneer species first appear.first appear.

– Eventually soil is Eventually soil is produced.produced.

– Grasses appear.Grasses appear.– Shrubs appear.Shrubs appear.– Finally trees Finally trees appear.appear.

Secondary Secondary SuccessionSuccession


• Disturbance leaves Disturbance leaves just soil intact.just soil intact.

• Secondary succession Secondary succession starts with grasses.starts with grasses.

• A stable climax A stable climax community results.community results.

• Some communities Some communities never reach stable never reach stable climax community.climax community.

Energy Energy Transfers Transfers

in in CommunitiesCommunities

ProducersProducers Monday 3/23/03Monday 3/23/03Pages 415-419Pages 415-419Section 22-1Section 22-1

• Producers use energy Producers use energy to produce organic to produce organic molecules.molecules.

• AutotrophsAutotrophs– Use energy to Use energy to produce produce carbohydrates.carbohydrates.

– Most are Most are photosynthetic.photosynthetic.

– Few are Few are chemosynthetic.chemosynthetic.

Measuring Measuring ProductiviProductivi

tyty

Monday 3/23/03Monday 3/23/03Pages 415-419Pages 415-419Section 22-1Section 22-1

• Gross Primary Gross Primary productivity:productivity:– The rate at The rate at which producers which producers capture energy.capture energy.

– Equal to all of Equal to all of the the carbohydrates carbohydrates produced using produced using photosynthesis.photosynthesis.

Measuring Measuring ProductiviProductivi

tyty


• Net Primary Productivity.Net Primary Productivity.– All organic material in an All organic material in an ecosystem is referred to as ecosystem is referred to as biomass.biomass.

– All stored energy in the All stored energy in the ecosystem.ecosystem.

– Rate at which biomass accumulates Rate at which biomass accumulates is NPP.is NPP.

– GPP - carbohydrates used for GPP - carbohydrates used for living.living.

ConsumersConsumers Monday 3/23/03Monday 3/23/03Pages 415-419Pages 415-419Section 22-1Section 22-1

• Consumers are Consumers are heterotrophs.heterotrophs.

• Obtain energy by Obtain energy by consuming organic consuming organic molecules.molecules.

• HerbivoresHerbivores• CarnivoreCarnivore• OmnivoreOmnivore• DetritivoreDetritivore• DecomposersDecomposers

Energy Energy FlowFlow


• Energy is transferred Energy is transferred from organism to from organism to organism.organism.

• Trophic level refers Trophic level refers to feeding position in to feeding position in communitycommunity

• Trophic levels:Trophic levels:– 1st level = 1st level = producersproducers

– 2nd level = 2nd level = herbivoresherbivores

– 3rd level = 3rd level = carnivorecarnivore

– 4th level = second 4th level = second carnivorecarnivore

Food Food ChainsChains


• A single pathway of A single pathway of energy through the energy through the ecosystem.ecosystem.

• Approximately 10% of Approximately 10% of energy is preserved energy is preserved in each transfer.in each transfer.

• 5% of sun’s energy 5% of sun’s energy is preserved in the is preserved in the producers.producers.

Food WebsFood Webs Monday 3/23/03Monday 3/23/03Pages 415-419Pages 415-419Section 22-1Section 22-1

• Several food Several food chains chains interlinked.interlinked.

• Better shows Better shows energy flow energy flow in an in an ecosystem.ecosystem.

BiogeochemicaBiogeochemical Cyclel Cycle

Wednesday 3/25/03Wednesday 3/25/03Pages 420-423Pages 420-423Section 22-2Section 22-2

• Energy flows Energy flows throughthrough an an ecosystem.ecosystem.

• Water and Water and minerals minerals recyclerecycle in the in the ecosystem.ecosystem.– Water Water NitrogenNitrogen

– Minerals Minerals CalciumCalcium

– Carbon Carbon PhosphorusPhosphorus

Water Water CycleCycle


• Availability of Availability of water determines water determines productivity.productivity.– EvaporationEvaporation– TranspirationTranspiration– PrecipitationPrecipitation

• 90% of water that 90% of water that evaporates in evaporates in ecosystem passes ecosystem passes through plants.through plants.

Carbon Carbon CycleCycle


• Carbon cycle is Carbon cycle is composed of two composed of two processes:processes:– PhotosynthesisPhotosynthesis– RespirationRespiration

• Autotrophs do ____.Autotrophs do ____.• Heterotrophs do Heterotrophs do ____.____.

• Detritivores do Detritivores do ____.____.

• Decomposers do Decomposers do ____.____.

Nitrogen Nitrogen CycleCycle


• All living organisms All living organisms need need nitrogennitrogen (N (N22))

• 78% of the atmosphere 78% of the atmosphere is composed of Nis composed of N2.2.

– Only usable to a few Only usable to a few organisms.organisms.

– Nitrogen fixationNitrogen fixation– Nitrogen fixation Nitrogen fixation bacteriabacteria..

• Breakdown of organic Breakdown of organic material results in material results in ammonia.ammonia.

• Nitrogen is returned Nitrogen is returned to the atmosphere.to the atmosphere.

Species-Area Species-Area effecteffect


• Larger areas Larger areas support higher support higher degree of degree of richness.richness.

• Example: islandsExample: islands

Community Community StabilityStability


• How well a How well a community with community with stands change.stands change.

• Species richness Species richness improves improves stability.stability.

• ExperimentExperiment– Grass plotsGrass plots

ecology of communities types of species interactions

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species benefits

warbler species

review slide

competing species

fundamental niche overlap

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poisonousboth poisonous

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