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8/18/16
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http://www.beatricebiologist.com
CommunityEcology
• Whatisacommunity?
CommunityEcology
• Community:allthepopulationsofallthespeciesthatinhabitade=inedarea
• CommunityEcologyisthestudyofrelationshipsamongthespecies
CommunityStructure
• Ecologicaldominance–largenumbersofafewspecies– Mostoftenareplants
Krogh, 2011
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Biodiversity
• Whatisbiodiversity?
Biodiversity
• Thevarietyoflivingthingsinacommunity(3types)
Biodiversity
• Geographicdiversity–thegeographicaldistributionofspeciespopulations
Biodiversity
• Speciesdiversity–thenumberofdifferentspecies
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Biodiversity
• Geneticdiversity–withinapopulation,themoreallelespresent,thehigherthebiodiversity
CommunityInteractions
• Terminology:– Habitat:thephysicalsurroundingsinwhichaspeciescanbefound
– Niche:anorganismsoccupation.• Whereitlives,whatiteats,whoeatsit,whodoesitcompeteorinteractwith?
CommunityInteractions
• Competition:whenoneorganismusesaresourceattheexpenseofanother– Interspeci=iccompetition:competitionforaresourcebetweentwoormorespecies
Krogh, 2011
CommunityInteractions
• Competition:whenoneorganismusesaresourceattheexpenseofanother– Interspeci=iccompetition:competitionforaresourcebetweentwoormorespecies
– Mostcompetitionisindirectandthewinneristhemostef=icientatdoingsomething
• Whathappenstotheloser?
Krogh, 2011
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CommunityInteractions
• Competition:whenoneorganismusesaresourceattheexpenseofanother– Interspeci=iccompetition:competitionforaresourcebetweentwoormorespecies
– Mostcompetitionisindirectandthewinneristhemostef=icientatdoingsomething
• Competitiveexclusion–when2speciescompeteforthesamelimited,vitalresourceonewillalwaysoutcompetetheotherandthusbringaboutlocalextinction
Krogh, 2011
CommunityInteractions
• Coexistance:sharingofahabitat,butnotcompetingwitheachother– DonethroughResourcePartitioning:dividingupofscarceresourcesamongspeciesthathavesimilarrequirements
CommunityInteractions
• Predation:oneorganismfeedingonpartsorallofasecondorganism– Herbivory:atypeofpredationinwhichplantsaretheprey,notanimals
– Parasitism:atypeofpredationinwhichthepredatorfeedsonprey,butitdoesnotkillitimmediatelyandmaynoteverkillit
CommunityInteractions
• Arms-race– Aspreyincreases,predatorsincreaseanddroppreylevelsthendeclinethemselves(HomeworkAssignment)
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CommunityInteractions
• Camou=lage–tohelpavoidgettingpreyedupon
Krogh, 2011
CommunityInteractions
• Mimicry:aphenomenonthroughwhichonespecieshasevolvedtoassumetheappearanceofanother
Krogh, 2011
CommunityInteractions
• Mimicry:aphenomenonthroughwhichonespecieshasevolvedtoassumetheappearanceofanother– Batesian:evolutionofonespeciestoresembleaspeciesthathasasuperiorprotectivecapability
Krogh, 2011
CommunityInteractions
• Mimicry:aphenomenonthroughwhichonespecieshasevolvedtoassumetheappearanceofanother– Müllerian:severalspeciesthathaveprotectionagainstpredatorscometoresembleeachother
• Botharedangerous
Krogh, 2011
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CommunityInteractions
• Mutualism:aninteractionbetweenindividualsoftwospeciesthatisbene=icialtobothindividuals
Krogh, 2011
CommunityInteractions
• Commensalism:aninteractionbetweenindividualsoftwospeciesinwhichonebene=itswhiletheotherisneitherharmedorhelped.
Krogh, 2011
CommunityInteractions
• Parasitism:aninteractionbetweenindividualsoftwospeciesinwhichonebene=itswhiletheotherisharmed.
