巨嘴鸟：森林演变的关键所在

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1、巨嘴鸟：森林演变的关键所在　　WalkingthroughtheAtlanticcoastalforestsofBrazilinthemorningislikeeavesdropping[偷听]onatoucan[巨嘴鸟]symphony[交响曲].Eachproducesitsownuniquesoundtocutthroughtheauditory[听觉的]clutter[混乱].Butoverthepastcentury，thetoucanshavebeendisappearing.Hunting，far

2、ming，logging[伐木]―it’salltakenabigtoll[产生负面影响]ontoucans.　　Withfewerandfewerbirds，thetoucansymphonyisdowntoamurmur[低语].They’rejustaboutgonefrommanypartsoftheforest.Anditappearsthattheirdisappearancekickstarted[（比喻）强劲推动]awholeevolutionary[进化的]changeintheforesti

3、tself，particularlyinitspalmtrees.　　AccordingtoresearchinthejournalScience，thisiswhathappened.Thedominant[占优势的]palmtreedependsonbirdstoeatitsfruitandthendefecate[通便]theseedssomewhere，soitwillgerminate[发芽]andgrowanewtree.　　MauroGalettiisabiologistattheEstadual

4、PaulistaUniversityinBrazil.Hesaystoucansplayabigpartinthisreproductive[生殖的]process[过程].　　MauroGaletti：Theselargebirds，theyhaveanextremely4importantroleintheforestnotonlybecausetheydisperse[散播]seeds，butbecausetheydisperselargeseeds.　　Thelargestpalmseeds，somet

5、hesizeofmarbles[弹球]，aretoobigformostbirdstoeatexceptforthosebig-mouthedtoucans.Soasthetoucansdisappeared，thepalmsthatmadebigseedswereoutofluck―noseeddispersers[分散器].Meanwhile，thepalmsthatwere　　genetically[从遗传学角度]disposed[处理]tomakesmallseedsdidjustfine；infact

6、，theythrived[茁壮成长]andstartedtodominate[占优势]theforest.Galetti：Theextinction[灭绝]oflargebirdschangedtheevolutionofthispalm.　　Now，humanshavealwaysbeenmessingwith[干扰]nature.Whenwecutdownforestsorprairie[大草原]，orwhenweover-hunt，wechangethemixofplantsandanimals.Buti

7、nthiscase，humansactuallyaltered[改变]thegeneticmakeup[组成]ofawildpalmtreepopulation，injustacentury，byaccident.　　Sowhathappensifthesesmall-seedpalmseventually[最后]takeover？Well，itturnsoutthatsmallerseedsaren’tsogood.Theydryupanddiefasterinhot，dryweather.Andscient

8、istspredict[预言]thatclimatechangewillmakepartsofBrazilhotteranddrier，somuchsothatthesepalmscouldbeintrouble.　　Galetti：Theimpacts[冲击]ontheforestcanbequite4dramatic[戏剧性的]becauseseveralanimalspecies