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1、ECOLOGYchapter50Ecology:Studyofinteractionsbetweenorganismsandtheirenvironment.Environmentincludesbothabiotic(non-living)andbiotic(living)components.Abiotic:light,water,nutrients,chemicals,rocks,weather,etc.Biotic:organisms.Organismscompetewith,parasitize,eatorareeate
2、nbyandchangetheenvironmentforotherorganisms.Ecologyexploresawiderangeofquestionsaboutwhatfactorscontrolthedistribution,abundanceandbehavioroforganisms.Forexample,RedKangaroosoccurprimarilyintheAustralianinteriorinsemiaridregions.DistributionofKangaroossuggestsanabioti
3、cfactor(precipitation)influencesit,butperhapspopulationsalsoinfluencedindirectlybybioticfactorssuchascompetitors,predators,foodavailabilityandparasites.Ecologistshavetoconsidermultiplefactorstoexplainpatternsofabundanceanddistribution.Ecologyhasmanysubfieldsofstudyran
4、gingfromecologyofindividualorganismstodynamicsoflandscapesOrganismalEcologyPopulationEcologyCommunityEcologyEcosystemEcologyLandscapeEcologyWewillexplorethesesequentiallyDistributionofspeciesBiogeography:studyofthebroadpatternsofdistributionoforganismsacrosstheglobe.P
5、atternsstronglyinfluencedbyhistoricalfactorssuchascontinentaldrift(seechapter26)andbarriersincludingmountainrangesandseas.Forexample,Australiapopulatedbymarsupialmammals(e.g.kangaroos,wombats,koalas)becauseplacentalmammalsdidnotcolonizeitbeforeitseparatedfromotherland
6、masses.TapirsfoundonlyinsoutheastAsiaandSouthAmerica.Ancestralpopulationsseparatedwhenlandmassesdiverged.RoleofdispersalindistributionAbilitytocrossbarriersaffectsdistribution.Thus,speciesofbirdsoftenmorewidelydistributedthanmammals.However,inabilitytoreachanareanoton
7、lyfactorthatlimitsdistribution.Abilitytosurviveinnewareaiscritical.Tosurviveandthrivespeciesmustbeabletocopewithbothbioticandabioticfactors.BioticfactorsThepresenceofcompetitorsorpredatorsmaylimitanorganismsabilitytoestablishitself.Forexample,algaeareeatenbyseaurchins
8、andlimpets,whichlimitstheabilityofseaweedstoestablishthemselvesonrocksBioticfactorsConversely,absenceofpredatorsandcompetito
