2019_2020学年新教材高中英语Unit5Intothewild讲义外研版.docx

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1、Unit5　Intothewild对于动物的灭绝，很多人猜测是气候的原因，其实，有时候人类才是动物生存最大的威胁。我们要保护动植物，与它们和谐相处。Climatechange,nothumanhunting,mayhavewipedoutthethylacine(袋狼),accordingtoanewstudybasedonDNAfromthylacines'bones.Themeateatingmarsupials(有袋动物)diedoutonmainlandAustraliaafewthousandyearsago,butsurvivedinTasmania,anisland

2、ofsoutheastAustraliaseparatedfromthemainland,untilthe1930s.Untilthen,scientistshadbelievedthecauseofthismainlandextinction(灭绝)wasincreasedactivityfromnativeAustraliansanddingoes(Australianwilddogs)．ScientistsbehindtheUniversityofAdelaidestudy,whichwaspublishedintheJournalofBiogeographyonThurs

3、day,collected51newthylacineDNAsamplesfromfossilbonesandmuseumskins—thelargestdatasetofthylacineDNAtodate.Thepaperconcludedthatclimatechangestartingabout4,000yearsago—inparticulardrierseasonscausedbytheweathersystemsknownasElNiño—SouthernOscillation(南方涛动)—waslikelythemaincauseofthemainlandexti

4、nction.TheancientDNAshowedthatthemainlandextinctionofthylacineswasrapid,andnottheresultoflossofgeneticdiversity.TherewasalsoevidenceofapopulationcrashinthylacinesinTasmaniaatthesameperiodoftime,reducingtheirnumbersandgeneticdiversity.AssociateProfessorJeremyAustinsaidTasmaniawouldhavebeenprot

5、ectedfrommainlandAustralia'swarmer,drierclimateduetoitshigherrainfall.Hearguedthatclimatechangewas“theonlythingthatcouldhavecaused,oratleaststarted,anextinctiononthemainlandandcausedapopulationcrashinTasmania.”“Theybothhappenedataboutthesametime,andtheothertwothingsthathadbeentalkedaboutinthe

6、pastthatmayhavedriventhylacinestoextinctiononthemainlandweredingoesandhumans.Sotheonlyexplanationleftisclimatechange.Andbecausethepopulationcrashhappenedatthesametimeandthespecieswentextinctonthemainland,ourargumentisthatthere'sacommonthemethereandtheonlycommonthemeisthatthereisthischangeincl

7、imate.”