Ecology: CommunitiesEcology: Communities

Organizational Hierarchy of LifeOrganizational Hierarchy of LifeMost Most ComplexComplex

LeastLeastComplexComplex sub-atomic particlessub-atomic particles

atomatommoleculemoleculemacromoleculemacromoleculeorganelleorganellecellcelltissuetissueorganorganorgan systemorgan systemorganismorganismpopulationpopulationcommunitycommunityecosystemecosystembiospherebiosphere

Non-livingNon-living

LivingLiving

Term Term DefinitionDefinition

PopulationPopulation Individuals of one species that Individuals of one species that occupy a given environmentoccupy a given environment

CommunityCommunity All populations in a common All populations in a common environmentenvironment

EcosystemEcosystem Organisms in community plus Organisms in community plus nonliving factorsnonliving factors

BiosphereBiosphere Zones of air, land and water at Zones of air, land and water at earth’s surface occupied by living earth’s surface occupied by living thingsthings

Interactions in CommunitiesInteractions in Communities

-Competition-Competition

-Predation-Predation

-Symbiosis-Symbiosis

Competition Relates to Niche OverlapCompetition Relates to Niche Overlap

Degree of competition is proportional to Degree of competition is proportional to the overlap in ecological niches of the overlap in ecological niches of competing speciescompeting species

Ecological niche = total way of life of all Ecological niche = total way of life of all members of a speciesmembers of a species

--Habitat--Habitat--Physiological needs such as--Physiological needs such as

temperature, moisture, nutrients temperature, moisture, nutrients--Behavior--Behavior--Interactions with other species--Interactions with other species

Outcomes of CompetitionOutcomes of CompetitionCompetitive Exclusion = One species eliminates the otherCompetitive Exclusion = One species eliminates the other

Grown inSeparateFlasks

Grown inthe SameFlask

Outcomes of Competition Outcomes of Competition Resource Partitioning: Use of small differences in Resource Partitioning: Use of small differences in

environment to fulfill needsenvironment to fulfill needs

Outcomes of CompetitionOutcomes of CompetitionCharacter Displacement: Through natural Character Displacement: Through natural

selection, two species diverge in selection, two species diverge in characteristics that overlapcharacteristics that overlap

Theoretical vs. Actual NicheTheoretical vs. Actual Niche

Theoretical Theoretical NicheNiche

Defined by Defined by Physiological Limits: Physiological Limits: needs for food, needs for food, water, temperature water, temperature

Actual NicheActual Niche Portion of Portion of Theoretical Niche Theoretical Niche that is used, limited that is used, limited by competitionby competition

Competition Between Two Species of Competition Between Two Species of Barnacles for Region Near the Ocean SurfaceBarnacles for Region Near the Ocean Surface

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Effects of PredationEffects of PredationPredation = eating of live organismsPredation = eating of live organisms

• Eliminates old and weak individuals Eliminates old and weak individuals

• Regulates numbers of both predators Regulates numbers of both predators and preyand prey

• Coevolution of predator and preyCoevolution of predator and prey

• Regulates diversity of populations in Regulates diversity of populations in communitycommunity

The sea star The sea star PisasterPisasteris a keystone species in is a keystone species in aquatic communities in aquatic communities in the Pacific Northwest.the Pacific Northwest.

Population Cycles in Predators and PreyPopulation Cycles in Predators and Prey

Coevolution of Predator and PreyCoevolution of Predator and Prey

Camouflage hides preyCamouflage hides prey

SymbiosisSymbiosisClose Interaction Between SpeciesClose Interaction Between Species

ParasitismParasitism One helped , other harmedOne helped , other harmed

SymbiosisSymbiosis MutualismMutualism Both helpedBoth helped

SymbiosisSymbiosis

CommensalismCommensalism One helped, other neither One helped, other neither helped nor harmedhelped nor harmed

Will the Monarch Butterfly Will the Monarch Butterfly be affected by the development be affected by the development of herbicide resistant crops?of herbicide resistant crops?