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1、GWD_RC_改版大全制作者:Hamiton@CDGWDTN1..........................................................2GWDTN2..........................................................8GWDTN3........................................................16G
2、WDTN4........................................................24GWDTN5........................................................31GWDTN6........................................................38GWDTN7.......................
3、.................................44GWDTN8........................................................53GWDTN9........................................................60GWDTN10..................................................
4、....68GWDTN11......................................................76GWDTN13......................................................91GWDTN14....................................................100GWDTN15...................
5、.................................105GWDTN16....................................................111GWDTN17....................................................118GWDTN18....................................................1
6、22GWDTN19....................................................129GWDTN20....................................................135GWDTN21....................................................144GWDTN22.........................
7、...........................150GWDTN23....................................................156GWDTN24....................................................161GWD1Q9toQ12:Overthelast150yearslargestretchesofsalmonhabitathavebe
8、eneliminatedbyhumanactivity:mininglivestockgrazingtimberharvestingagricultureaswellasrecreationalurbandevelopment.Thenumericaleffectisobvious:therearefewersalmonindegradedregionsthaninpristineoneshoweverhabitatlossalsoha
9、sthepotentialtoreducegeicdiversity.Thisismostevidentincaseswhereitresultsintheextinctionofentiresalmonpopulations.Indeedmostanalystsbelievethatsomekindofenvironmentaldegradationunderliesthedemiseofmanyextinctsalmonpopula
10、tions.Althoughsomerivershavebeenrecolonizedtheuniquegenesoftheiginalpopulationshavebeenlost.Largescaledisturbancesinonelocalealsohavethepotentialtoalterthegeicstructureofpopulationsinneighbingareasevenifthoseareashavepri
11、stinehabitats.WhyAlthoughthehominginstinctofsalmontotheirnatalstreamisstrongafractionofthefishreturningfromthesea(rarelymethan15percent)strayspawninnearbystreams.Lowlevelsofstrayingarecrucialsincetheprocessprovidesasourc
12、eofnovelgenesamechanismbywhichalocationcanberepopulatedshouldthefishtheredisappear.Yethighratesofstrayingcanbeproblematicbecausemisdirectedfishmayinterbreedwiththeexistingstocktosuchadegreethatanylocaladaptationsthatarep
13、resentbecomediluted.Strayingratesremainrelativelylowwhenenvironmentalconditionsarestablebutcanincreasedramaticallywhenstreamssufferseveredisturbance.The1980volcaniceruptionofMountSaintHelensfexamplesentmuddebrisintosever
14、altributariesoftheColumbiaRiver.Fthenextcoupleofyearssteelheadtrout(aspeciesincludedamongthesalmonids)returningfromtheseatospawnwerefcedtofindalternativestreams.Asaconsequencetheirratesofstrayinginitially16percentrosetom
15、ethan40percentoverall.AlthoughnoonehasquantifiedchangesintherateofstrayingasaresultofthedisturbancescausedbyhumansthereisnoreasontosuspectthattheeffectwouldbequalitativelydifferentthanwhatwasseenintheaftermathoftheMountS
16、aintHelenseruption.Suchadramaticincreaseinstrayingfromdamagedareastomepristinestreamsresultsinsubstantialgeneflowwhichcaninturnlowertheoverallfitnessofsubsequentgenerations.GWD1Q9:TheprimarypurposeofthepassageistoA.argue
17、againstaconventionalexplanationftheextinctionofcertainsalmonpopulationssuggestanalternativeB.crectacommonmisunderstingaboutthebehaviofsalmoninresponsetoenvironmentaldegradationcausedbyhumanactivityC.comparetheeffectsofhu
18、manactivityonsalmonpopulationswiththeeffectsofnaturaldisturbancesonsalmonpopulationsD.differentiatetheparticulareffectsofvarioushumanactivitiesonsalmonhabitatsE.describehowenvironmentaldegradationcancausechangesinsalmonp
19、opulationsthatextendbeyondanumericalreductionGWD1Q10:ItcanbeinferredfromthepassagethattheoccasionalfailureofsomesalmontoreturntotheirnatalstreamsindertospawnprovidesamechanismbywhichA.pristinestreamsthatarenearpollutedst
20、reamsbecomepollutedthemselvesB.theparticularadaptationsofapollutedstream’ssalmonpopulationcanbepreservedwithoutdilutionC.thenumberofsalmoninpristinehabitatsdecreasesrelativetothenumberinpollutedstreamsD.anenvironmentally
21、degradedstreamcouldberecolonizedbynewsalmonpopulationsshouldthestreamrecoverE.theextinctionofthesalmonpopulationsthatspawninpollutedstreamsisacceleratedGWD1Q11:Accdingtothepassagehumanactivityhashadwhichofthefollowingeff
22、ectsonsalmonpopulationsA.AnincreaseinthesizeofsalmonpopulationsinsomepreviouslypollutedriversB.AdeclineinthenumberofsalmoninsomeriversC.AdecreaseinthenumberstrayingsalmoninsomeriversD.Adecreaseinthegeneflowbetweensalmonp
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