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1、环境概论IntroductiontoEnvironment董方土木与水利工程学院dongfang@mail.ustc.edu.cn第2讲Ecosystem,LivingOrganismsandPhysicalEnvironment生态系统,生命有机物与自然环境Outline提要3.1Evolution:HowPopulationsChangeOverTime进化:种群随时间如何变化.NaturalSelection自然选择;TheKingdomsoflife生命的界3.2BiologicalCommunities生物群落Succession:HowCommu
2、nitiesChangeoverTime演替:群落随时间如何变化3.3KeystoneSpecies关键物种3.4InteractionsAmongOrganisms有机体之间相互关系3.5Symbiosis共生现象Coevolution共同进化;Mutualism互利共生;Commensalism偏利共生Parasitism:TakingatAnother’sExpense寄生现象:牺牲他人利益3.5Predation捕食3.6Competition竞争3.7TheEcologicalNiche生态小生境（生态位）生物入侵:水葫芦入侵东非Victoria湖
3、3.1Evolution:HowPopulationsChangeOverTime进化:种群随时间如何变化.Evolutionisageneticchangeinapopulationoforganismsthatoccursovertime.CharlesDarwin(1809-1882),a19th-centurynaturalist,proposedthemechanismofevolutionthatisstillacceptedbythescientificcommunitytoday.Asyouwillsee,theenvironmentplay
4、sacrucialroleinDarwin’stheoryofevolution.ItoccurredtoDarwinthatovertime,inheritedtraitsfavorabletosurvivalinagivenenvironmentwouldtendtobepreserved,whereasunfavorableoneswouldbeeliminated.Theresultwouldbeadaptation,evolutionaryreproductivesuccessofthepopulationinagivenenvironment.E
5、ventuallytheaccumulationofmodificationsmightresultinanewspecies.TheOriginofSpeciesbyMeansofNaturalSelection自然选择方式的物种起源.NaturalSelection自然选择Darwin’smechanismofevolutionisbynaturalselection,inwhichbetter-adaptedindividuals-thosewithacombinationofgenetictraitsbettersuitedtoenvironment
6、alconditions-aremorelikelytosurviveandreproduce,increasingtheirproportioninthepopulation.Overtime,thepopulationchangesasfavorabletraitsincreaseinfrequencyinsuccessivegenerations,andasunfavorabletraitsdecreaseordisappear.Naturalselectionconsistsoffourobservationsaboutthenaturalworld
7、:overproduction,variation,limitsonpopulationgrowth,anddifferentialreproductivesuccess.Becauseoffspringtendtoresembletheirparents,thenextgenerationobtainstheparents’heritabletraits.Thebest-adaptedindividualsarethosethatreproducemostsuccessfully,whereasless-fitindividualsdiepremature
8、lyorproducefewerorinferior
