1、ECOLOGYchapter50 Ecology Studyofinteractionsbetweenorganismsandtheirenvironment Environmentincludesbothabiotic non living andbiotic living components Abiotic light water nutrients chemicals rocks weather etc Biotic organisms Organismscompetewith parasitize eatorareeatenbyandchangetheenvironmentforot
2、herorganisms Ecologyexploresawiderangeofquestionsaboutwhatfactorscontrolthedistribution abundanceandbehavioroforganisms Forexample RedKangaroosoccurprimarilyintheAustralianinteriorinsemiaridregions DistributionofKangaroossuggestsanabioticfactor precipitation influencesit butperhapspopulationsalsoinf
3、luencedindirectlybybioticfactorssuchascompetitors predators foodavailabilityandparasites Ecologistshavetoconsidermultiplefactorstoexplainpatternsofabundanceanddistribution EcologyhasmanysubfieldsofstudyrangingfromecologyofindividualorganismstodynamicsoflandscapesOrganismalEcologyPopulationEcologyCom
4、munityEcologyEcosystemEcologyLandscapeEcologyWewillexplorethesesequentially Distributionofspecies Biogeography studyofthebroadpatternsofdistributionoforganismsacrosstheglobe Patternsstronglyinfluencedbyhistoricalfactorssuchascontinentaldrift seechapter26 andbarriersincludingmountainrangesandseas For
5、example Australiapopulatedbymarsupialmammals e g kangaroos wombats koalas becauseplacentalmammalsdidnotcolonizeitbeforeitseparatedfromotherlandmasses TapirsfoundonlyinsoutheastAsiaandSouthAmerica Ancestralpopulationsseparatedwhenlandmassesdiverged Roleofdispersalindistribution Abilitytocrossbarriers
6、affectsdistribution Thus speciesofbirdsoftenmorewidelydistributedthanmammals However inabilitytoreachanareanotonlyfactorthatlimitsdistribution Abilitytosurviveinnewareaiscritical Tosurviveandthrivespeciesmustbeabletocopewithbothbioticandabioticfactors Bioticfactors Thepresenceofcompetitorsorpredator
7、smaylimitanorganismsabilitytoestablishitself Forexample algaeareeatenbyseaurchinsandlimpets whichlimitstheabilityofseaweedstoestablishthemselvesonrocks Bioticfactors Conversely absenceofpredatorsandcompetitorshasallowedmanyorganismsintroducedintonewareastoincreasesomuchtheybecomepests E g Japanesebe
8、etles fromAsia zebramusselsandpurpleloosestrifefromEurope Melaleuca EucalyptustreesfromAustralia andmanyotherinvasivespecieshavespreadwidelyintheU S Abioticfactors Themajorfactoraffectingdistributionofterrestrialorganismsisclimate whichincorporatestemperature sunlight windandprecipitation Abioticfac
9、tors Climateisdeterminedbyglobalfactorssuchasinputsofsolarenergyandthemovementoftheearththroughspace Studydiscussionofclimatepatternspages1088and1089 Climate Localfactorssuchasthepresenceofmountainsandlargebodiesofwateralsoaffectclimate Mountainsforceupmoistairmovingacrossthem Astheaircoolsthewaterc
10、ondensesandfallsasrain Theresultisthatonesideofthemountainrangeiswetandtheothersideisdrier andperhapsadesert e g MojaveandGobiDeserts Climate Largebodiesofwatermoderateclimate Landheatsfasterthanwaterandwarmairrises Coolerairoverwatermovesinandreplacesthewarmair Thewarmairthatwasoverlandcoolsathigha
11、ltitudeandsinksoverwater Resultsissteadyflowofcoolairoverland TerrestrialBiomes Biomesaremajortypesofecosystemsthatcoverlargeareasoftheearthandareclassifiedbytheirdominantvegetationtypes anecosystemisthecommunityoforganismsinanareaandtheirphysicalenvironment Eachbiomealsoispopulatedbyadiversearrayof
12、animals fungiandmicroorganismsadaptedtothatenvironment Majorterrestrialbiomesinclude TropicalforestDesertTemperateGrasslandSavannaTemperatebroadleafforestConiferousforest Taiga Tundra seedescriptionspages1100 1104 Savannah Terrestrialbiomes Terrestrialbiomesoftenverticallystratified Layersdefinedbyd
13、ifferentsizeplants e g inforeststhereisanuppercanopyoftalltrees lowtreelayer shrublayer groundlayerofherbaceousplants litterlayerandrootzone Stratificationprovidesmultipledifferenthabitatsforanimalswhichoccupyspecializedfeedingniches Convergentevolution Actualspeciesinabiomedifferfromoneareatoanothe
14、rbuttheypossesssimilaradaptations Thisisconvergentevolution developmentofsameevolutionarysolutionstoecologicalproblems Convergentevolution Forexamplevegetationinalldesertsworldwidecharacterizedbyextensiverootsystems long termwaterstoragecapability thickwaxycoveringstoreducewaterloss andextremelysmal
15、l ifany leaves Biomesoftenmaintainedbydisturbance Wildfiresareanessentialfactorinmaintainingmanybiomes e g grasslands savannahs someconiferousforests Firefavorstreessuchaslongleafpinewhosebarkresistsfireandgrasses whichrecoverquicklyafterburning Aquaticbiomes Aquaticbiomeslessinfluencedbyclimatethan
16、terrestrialbiomesWhy Aquaticbiomes Waterismorethermallystable Ittakesalotofheattochangethetemperatureofabodyofwater Majoraquaticbiomes LakesRiversEstuariesIntertidalzoneMarinepelagiczoneCoralreefsMarinebenthiczone benthiczoneissea lakefloor Seepages1094 1097 Aquaticbiomesoftenstratifiedbylightandtem
17、perature Lightintensitydecreaseswithdepth Upper photic zonesupportsphotosynthesis Inoceanphoticzonenarrowbutcontainsmostorganisms Aphoticzonesparselypopulated Benthiczone bottom organismsoftendependonrainofdeadorganicmatter detritus fromabove Thermalstratificationoflakes Intemperateareaslakesarethermallystratifiedinsummerandwinter Waterdensestat4 Csowateratthistemperaturesinksthroughcolderorwarmerwater Thus inspringandfallallwaterinlakemixeswhichredistributesnutrientsthroughoutthelake
