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时间:2019-11-11
《2019_2020学年新教材高中英语Unit5Intothewild讲义外研版.docx》由会员上传分享,免费在线阅读,更多相关内容在教育资源-天天文库。
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.”
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