3.3ThreatstoBiodiversity(Pages100-109)

LearningGoals

•Icanexplainhowbiodiversityisthreatenedbyhabitatloss,alienspecies,overexploitation,disruptingconnectivityacrossecosystemsandextinction.•Icanexplainhowbiodiversityisbeneficialtohumans.•Icansuggestwaystopreservebiodiversity.

KeyConcepts•Threatstobiodiversityincludehabitatloss,theintroductionofalienspecies,overexploitation,andbreakingtheconnectivityamongecosystems.•Deforestationanddrainingwetlandscanresultinhabitatloss.•VIDEO:ZebraMussels

KeyConcepts

•ExtinctionisanaturaleventthathasoccurredthroughoutEarth’shistory.•Currentextinctionratesmaybeacceleratedduetohumanactivities.

HabitatLoss

•HABITATLOSS:thedestructionofhabitats,whichusuallyresultsfromhumanactivities•Examples•Deforestation•DrainingWetlands

Deforestation•DEFORESTATION:thepracticeofclearingforestsforloggingorotherhumanuses,andneverreplantingthem

DrainingWetlands

•Wetlands:areasoflandthatarecoveredbywaterforpartoralloftheyear• Importantecosystemformanydifferentspecies•Coverabout14%ofCanada'stotallandarea

ImportanceofWetlands

AlienSpecies

•ALIENSPECIES:aspeciesthatisaccidentallyordeliberatelyintroducedintoanewlocation• INVASIVESPECIES:aspeciesthatcantakeoverthehabitat ofnativespecies•AliensHaveLandedI•AliensHaveLandedII

ZebraMussels:AnInvasiveSpecies

Zebramusselswereeatingmostoftheshrimp-likecrustaceanswhichareafoodsourceformanyfish,includingwhitefishandsmelt.Asthenumberofthesecrustaceanshasdeclined,sohavethenumbersofthesefish.Nativeclamsandmusselshaveexperiencedasignificantdeclineinnumbers,aszebramusselshaveoutcompetedwiththemforfood.

Practice

•Page109#1-8•Answerthefollowingquestions:

1. Whatisoverexploitation?2. Howcandisruptinganorganismthatexistsin

multipleecosystemseffectconnectivity?3. Whatisextinction?Whataresomecausesof

extinction?•Read“TheZebraMussel”handout• Socrative3.3miniquiz

Overexploitation•OVEREXPLOITATION: theuseorextractionofaresourceuntilitisdepleted•ThereducedcatchofAtlanticcodreflectsadecreaseinpopulationasaresultofoverexploitation

DisruptingConnectivityAcrossEcosystems

• Somespeciesareresponsibleforsustainingmultipleecosystems

Extinction

•EXTINCTION: thedeathofalltheindividualsofaspecies

•Backgroundextinctionà slow,steady,minorchanges•Massextinctionà sudden,rapid,majorchanges•Biodiversitycrisis:thecurrentacceleratedrateofextinctions

Somecausesofextinctionare:• Overhunting• Climatechange• Largemeteorimpacts• Disease• Invasivespecies• Urbansprawlandlossofhabitat

Thepassengerpigeon isanextinctNorthAmericanbird.ItwasoncethemostabundantbirdinNorthAmerica,andpossiblytheworld. ItaccountedformorethanaquarterofallbirdsinNorthAmerica.Thespecieslivedinenormousmigratoryflocksuntiltheearly20thcentury,whenhuntingandhabitatdestructionledtoitsdemise.

Oneflockin1866insouthernOntariowasdescribedasbeing1.5 kmwideand500 kmlong,took14hourstopass,andheldinexcessof3.5billionbirds.

Potentialde-extinctionSomehavesuggestedcloningthepassengerpigeoninthefuture.De-extinction effortsarenowunderwaytorevivethespeciesbyextractingDNAfragmentsfrompreservedspecimens,andlater,usingband-tailedpigeonsassurrogateparents.[

Practice

•Page109#1-8• Socrative3.3miniquiz• ProjectDUETHURSDAY(model),FRIDAY(writtenpiece)!