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1、bymeiosis,onlyonecellfarawayfrombeadsholecontinuedtodevelopintotheembryosac.Mononuclearembryosacformedtwonuclearafterfirstdivision,withtheformationofvacuoles,twonuclearsacmovedtobothendsandformedatwo-nucleateembryosac.ThedevelopmentofSinowilsoniaovulebelongedt
2、oPolygonum-shapedsac.4.AnalysisofGeneticDiversityThroughextractingDANofSinowilsonia,rDNA-ITSregionwasamplifiedbyPCRandsequenced.GeneticanalysiswasconductedbyusingClustal,DnaSP,MEGA,andAlequinesoftware.TheresultsshowedthatITShadatotallengthof817bp,andnogap.Thew
3、holeITShad15variablesites,11convertingsites,4transversionsites,andthenumberofinformationsitesreached11.ThegeneticdifferentiationcoefficientofAMOVAanalysisis0.5063,indicatingthatgeneticvariationofSinowilsoniamainlyexistedamongpopulations,andthegeneticdiversitya
4、tthespecieslevelandgrouplevelwereatlowlevels,thegeneticdifferentiationamongpopulationswassignificantlydifference.TheresultsofManteltest(r=0.51,p=0.01)showedthatthegeneticdistancebetweenpopulationscorrelatedwithgeographicaldistance,indicatingthegeographicisolat
5、ionplayedanimportantroleintheformationofgeneticstructureofSinowilsoniapopulation.5.MechanismsofendangerandendangeredspeciesprotectionTheendangeredreasonsofSinowilsoniacamefromtwoaspectsofitsinternalandexternalaspects.Internalfactorsmainlyreflectedintwoaspects:
6、First,Sinowilsoniahadloweradaptationofenvironmentalchangesforitsecologicalamplitude;Second,itwastheslow-growingspecies,hadsmallgrouppopulations,andeasilygeneratedgeneticdrift.Externalfactorsmainlyreflectedinthedestructionoftheirhabitats,decliningtheeffectivepo
7、pulationofSinowilsonia,leadingtotheincreaseofinbreedingandinbreedingdepression,andultimatelydeclineditsadaptationandviability.Sinowilsoniageneticstructureofpopulationshadbeeneffectedbythelong-termhistoricalevolutionandecology,includedchangingdistribution,habit
8、atfragmentationandpopulationisolation.Therefore,underthesmallpopulationsandbothlargepopulations,thisstudyformulatedaconservation-basedprotectionstrategyinordertopreventthedeclineof
