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1、新GRE閱讀機(jī)經(jīng)：鳥叫研究 下面是小編為大家整理的新GRE機(jī)經(jīng)的閱讀部分，這篇是關(guān)于“鳥叫研究”的新GRE閱讀機(jī)經(jīng)，希望可以幫助各位考生打開閱讀思路，提高新GRE閱讀能力。 鳥叫研究 Overtheyears,biologistshavesuggestedtwomainpathwaysbywhichsexualselectionmayhaveshapedtheevolutionofmalebirdsong.Inthefirst,malecompetitionandintrasexualselectionproduce
2、relativelyshort,simplesongsusedmainlyinterritorialbehavior.Inthesecond,femalechoiceandintersexualselectionproducelonger,morecomplicatedsongsusedmainlyinmateattraction;likesuchvisualornamentationasthepeacock’stail,elaboratevocalcharacteristicsincreasethemale’schance
3、sofbeingchosenasamate,andhethusenjoysmorereproductivesuccessthanhislessostentatiousrivals.Thetwopathwaysarenotmutuallyexclusive,andwecanexpecttofindexamplesthatreflecttheirinteraction.Teasingthemaparthasbeenanimportantchallengetoevolutionarybiologists. Earlyresear
4、chconfirmedtheroleofintrasexualselection.Inavarietyofexperimentsinthefield,malesrespondedaggressivelytorecordedsongsbyexhibitingterritorialbehaviornearthespeakers.Thebreakthroughforresearchintointersexualselectioncameinthedevelopmentofanewtechniqueforinvestigatingf
5、emaleresponseinthelaboratory.Whenfemalecowbirdsraisedinisolationinsound-proofchamberswereexposedtorecordingsofmalesong,theyrespondedbyexhibitingmatingbehavior.Byquantifyingtheresponses,researcherswereabletodeterminewhatparticularfeaturesofthesongweremostimportant.I
6、nfurtherexperimentsonsongsparrows,researchersfoundthatwhenexposedtoasingle24songtyperepeatedseveraltimesortoarepertoireofdifferentsongtypes,femalesrespondedmoretothelatter.Thebeautyoftheexperimentaldesignisthatiteffectivelyrulesoutconfoundingvariables;acousticisola
7、tionassuresthatthefemalecanrespondonlytothesongstructureitself. Ifintersexualselectionoperatesastheorized,maleswithmorecomplicatedsongsshouldnotonlyattractfemalesmorereadilybutshouldalsoenjoygreaterreproductivesuccess.Atfirst,however,researchersdoingfieldworkwiths
8、ongsparrowsfoundnocorrelationbetweenlargerrepertoiresandearlymating,whichhasbeenshowntobeoneindicatorofreproductivesuccess;further,commonmeasures
