High clonal diversity in threatened peripheral populations of the yellow bird’s

AnnalsofBotanyPage1of8

doi:10.1093/aob/mcr003,availableonlineat

Highclonaldiversityinthreatenedperipheralpopulationsoftheyellowbird’s

nest(Hypopitysmonotropa;syn.Monotropahypopitys)

GemmaE.BeattyandJimProvan*

SchoolofBiologicalSciences,Queen’sUniversityBelfast,97LisburnRoad,BelfastBT97BL,NorthernIreland,UK

*Forcorrespondence.E-mail:J.Provan@qub.ac.uk

Received:15September2010Returnedforrevision:24November2010Accepted:2December2010

BackgroundandAimsPeripheralpopulationsofplantspeciesareoftencharacterizedbylowlevelsofgeneticdiversityasaresultofgeneticdrift,restrictedgene ow,inbreedingandasexualreproduction.Theseeffectscanbeexacerbatedwhererange-edgepopulationsarefragmented.ThemainaimofthepresentstudywastoassessthelevelsofgeneticdiversityinremnantpopulationsofHypopitysmonotropa(syn.Monotropahypopitys;yellowbird’snest)attheedgeofthespecies’EuropeanrangeinNorthernIreland,sincetheseremnantpopulationsaresmallandhighlyfragmented.

MethodsEveryplantfoundthroughsurveysof21extantpopulationswasgenotypedforeightmicrosatellitelocitoestimatelevelsandpatternsofgeneticdiversityandclonality.

KeyResultsLevelsofgeneticdiversitywererelativelyhighinthepopulationsstudied,andtheincidenceofclonalreproductionwasgenerallylow,withameanofonly14.45%ofclonalindividuals.Clonesweresmallandhighlyspatiallystructured.Levelsofinbreeding,however,werehigh.

ConclusionsTheobservedlowlevelsofclonalitysuggestthatthemajorityofgenetsinthepopulationsofH.monotropastudiedarefertileandthatreproductionispredominantlysexual.Asthespeciesishighlyself-com-patible,itislikelythatthehighlevelsofinbreedingobservedinthepopulationsinthepresentstudyaretheresultofself-pollination,particularlygiventhesmallnumbersofindividualsinmostofthepatches.Giventhisextentofinbreeding,furthergeneticmonitoringwouldbeadvisabletoensurethatgeneticdiversityismaintained.Keywords:Clonality,conservation,distributionrange,fragmentation,inbreeding,Hypopitysmonotropa,Monotropoideae,Pyrolaceae.

INTRODUCTION

1984;Caughleyetal.,1988).Theseperipheralpopulations

tendtobecharacterizedbylowlevelsofwithin-populationInplants,contemporaryfactorsdetermininglevelsofwithingeneticdiversitycombinedwithhighlevelsofgeneticdiffer-andbetweenpopulationgeneticvariationareoftenassociatedentiationbetweenpopulations(VucetichandWaite2003;withdifferencesinmatingsystems(sexualvs.asexual,sel ngEckertetal.2008),andthesecouldbecompoundedbyvs.outcrossing)andsincemanyspeciesofplantdisplay exi-asexualreproductionorprocessessuchasgeitonogamy,i.e.bilityinreproductivestrategy,differingmodesofreproductioncross-fertilizationbetweenrametsofthesamegenet.Ithasunderavarietyofenvironmentalconditionsdirectlyaffectalsobeensuggested,however,thattheserangeedgepopu-levelsofdiversity.Clonalreproductioniswidespreadinlationsmaybemorelikelytoharboursomedegreeofadaptiveplantsandcanoccurviavegetativespread,resultinginthecre-potentialthatthespeciesmayultimatelyneedtosurvivetheationofoneormoregeneticallyidenticalramets,whichhavechangingconditionsarisingfrompresent-dayglobalgrownfromanoriginalprogenitorplant(genet).Clonalwarming(LesicaandAllendorf,1995;Booyetal.,2000;growthhaslongbeenviewedasamechanismtoallowanindi-HampeandPetit,2005).

vidualtopersistinadverseconditions,andfactorscausingHypopitysmonotropa(Ericaceae;syn.Monotropahypop-plantstomaketheswitchfromsexualtoclonalreproductionitys),commonlyreferredtoasyellowbird’snestorpinesap,areoftencorrelatedwithsuboptimalenvironmentalconditionsisaherbaceousperennialplantfoundintemperateregions(TybjergandVestergaard,1992;Eckert,2002;HonnayandwithinEurope,AsiaandNorthAmerica.ThroughoutitsBossuyt,2005;Silvertown,2008).Advantagesofclonalrepro-rangethespeciesisconsideredscarce(Wallace,1975),andductioninsuchmarginalhabitatsincludetheabilitytoproducewithintheUKmostoftheextantpopulationsaremainlynewindividualsintheabsenceofamateandrelativespeedofrestrictedtothesouth-easterncountiesofEngland.Indevelopmentandhardinessoframetsrelativetoseedlings.NorthernIreland,thespeciesexistsatthewesternedgeofitsHabitatfragmentationandlosshavealsobeenimplicatedindistributionrangeinEuropeandisextremelyrareduetothecausingplantpopulationstoallocatemoreresourcestovegeta-limitedoccurrenceofitspreferredtemperatewoodlandtivereproduction(Smithetal.,2003;Lhullieretal.,2006).habitat,anditnowoccursonlyintworegions,namelyPopulationfragmentationisacommonoccurrenceatthearoundtheLowerLoughErneregioninCo.Fermanagh,andedgeofaspecies’ecologicalrange,dueinasmallstretchofwoodlandalongtheCo.Antrimcoastathabitat(Soule´toalackofsuitable

,1973;ShumakerandBabble,1980;Brown,Straidkilly(Fig.1).Thespeciesisaself-compatible

#TheAuthor2011.PublishedbyOxfordUniversityPressonbehalfoftheAnnalsofBotanyCompany.Allrightsreserved.

ForPermissions,pleaseemail:journals.permissions@

Downloaded from at Queens University of Belfast on January 21, 2011

Page2of8Beatty&Provan—ClonaldiversityinH.monotropa

FIG.1.Mapshowinglocationsofpopulationsanalysedinthisstudy.InsetmapsshowStraidkillypopulations(S1–S4),CastleCaldwellpopulations

(CC1–CC6)andElyLodgepopulations(EL1–8).TheKnockninnypopulationisnotshown.

Downloaded from at Queens University of Belfast on January 21, 2011

Beatty&Provan—ClonaldiversityinH.monotropa

Page3of8

hermaphroditeandplantscanreproducebothsexuallyandclonally.Hypopitysmonotropaisepiparasitic,persistingundergroundforthemajorityoftheyearandproducingaerialspikesfromlateJulyuntillateSeptember.Insectpolli-natorshavebeennotedvisitingthe owers(Wallace,1977),andwhenseedproductiondoesoccur,persistenceofseedlingsisdependentonthepresenceofmycorrhizalfungiofthegenusTricholoma,asisthecasewithmanymembersoftheEricaceae(BidartondoandBruns,2001;Leakeetal.,2004).ThemainaimofthepresentstudywastoassessthelevelsofgeneticdiversityintheremainingpopulationsofH.monotropainNorthernIreland.ApreviousstudyonanothermemberoftheMonotropoideae,Orthiliasecunda,whichalsoexistsasaseriesofsmall,highlyfragmentedpopulationsattheedgeofitsrangeinNorthernIreland,revealedextremelyhighlevelsofclonality(Beattyetal.,2008).Eachpopulationcomprisedasingleclone,withacompletelackofwithin-populationgeneticvariation.Consequently,wewereparticularlyinter-estedindeterminingwhethertheseperipheralpopulationsofH.monotropawerealsocharacterizedbyhighlevelsofclonalgrowth,sinceextantpopulationsofbothspeciesarerestrictedtothesametwoareasandsincesuchdataisimpor-tantfortheformationofrational,sustainableconservationmeasuresforthesethreatenedpopulations.

MATERIALSANDMETHODS

Surveysandstudypopulations

Surveyswerecarriedoutin2007and2008forCo.Fermanaghpopulations,and2009and2010forCo.Antrimpopulations.AllsiteswhereHypopitysmonotropahadpreviouslybeenrecordedwerevisitedandthenumbersofplantspresentwererecordedandtheirpositionsineachpopulationmapped(Fig.1andTable1).ErrigalBanks,Co.Londonderry,wasalsosurveyedin2007and2008,sincethespecieshadpre-viouslybeenrecordedthere,althoughithadnotbeenfoundinrecentyears.

SamplingandDNAextraction

HypopitysmonotropaisprotectedunderSchedule8oftheWildlife(NorthernIreland)Order(1985)and,assuch,itisanoffencetopick,uprootordestroytheplant.Consequently,twoscalesweretakenfromeachplantandstoredinsilicagelfortransportationtothelaboratory.DNAwasextractedfromonescaleperindividualusingtheQiagenDNeasyPlantMiniKit,afteraninitial3-mingrindingat30HzusingaRetschMM300mixermill.DNAwasquan-ti edvisuallyon1%agarosegelsstainedwithethidiumbromideanddilutedtoaconcentrationof50ngmL21forsub-sequentPCR.

Microsatellitegenotyping

Individualsweregenotypedfor veH.monotropamicrosa-tellitelocipreviouslydescribedinKloosteretal.(2009):Mono02,Mono15,Mono20,Mono21andMono22.ThreeadditionallocidevelopedforthisstudyusingtheISSR-cloningtechniqueoutlinedinProvanandWilson

(2007)werealsoused(Table2).Forwardprimersweremodi- edbytheadditionofa19-bpM13tail(5′-CACGACGTTGTAAAACGAC-3’)andreverseprimersweremodi edbytheadditionofa7-bptail(5’-GTGTCTT-3’).PCRwascarriedoutinatotalvolumeof10mLcontaining100nggenomicDNA,10pmolofdye-labelledM13primer(6-FAMorHEX),1pmoloftailedforwardprimer,10pmolreverseprimer,1×PCRreactionbuffer,200mMeachdNTP,2.5mMMgCl2and0.25UGoTaqFlexiDNApolymerase(Promega).PCRwascarriedoutonaMWGPrimusthermalcyclerusingtheconditionsdescribedinKloosteretal.(2009)andgenotypingwascarriedoutonanAB3730xlcapil-larygenotyping.system.AllelesizeswerescoredinGENEMAPPERV41(AppliedBiosystems)usingLIZ-500sizestandardsandwerecheckedbycomparisonwithpreviouslysizedcontrolsamples.

Dataanalysis

AsH.monotropapossessesthecapacityforclonalreproduc-tion,clonemateswereidenti edbycalculatingtheprobability(PGEN)ofeachmulti-locusgenotype(MLG)arisingthroughsexualasopposedtoclonalreproductionfollowingthemethodofParksandWerth(1993):

PGEN=[2hP(x1ix2i)]n 1

wherehisthenumberoflociatwhichthegenotypeishetero-zygous,xotypeatlocus1iistheallelefrequencyofthe rstalleleinthegen-i,xat2iistheallelefrequencyofthesecondalleleinthegenotypelocusi.Theobservationofheterozygosityallowsthedifferentiationbetweengeneticidentityduetoclonalpropagationandidentityduetoinbreedingorsel ng,whichwouldleadtoanincreaseinhomozygosity.SampleswhichsharedMLGswithPGEN,0.05wereconsideredclone-matesandidenti edassuchonthemaps,andduplicategeno-typeswereremovedfromsubsequentanalyses.PwerecalculatedusingtheGGENvaluesENCLONEsoftwarepackage(V2.0;Arnaud-HaondandBelkhir,2007).Levelsofexpectedhetero-zygosity(HE)basedonnuclearmicrosatelliteallelefrequen-cieswerecalculatedusingtheARLEQUINsoftwarepackage(V3.01;Excof eretal.,2005)forpopulationswithasamplesizeofN≥5.Thesigni canceofdifferencesinvaluesofHEbetweenyearswasestimatedusingtwo-tailedpairedt-tests,andaSpearman’srankcorrelationcoef cientwascal-culatedtotestforanyassociationbetweenpopulationsizeandgeneticdiversity.Levelsofclonaldiversitywereestimatedbycalculatinggenotypicrichness(R),de nedas(G–1)/(N–1),whereGisthenumberofMLGsandNisthenumberofplantsinthepopulation.Wheresampleswerelocatedinsuccessiveyears,anestimateofpopulationsizewasderivedusingasimplecapture–recaptureformula(numberofMLGsinyear1×numberofMLGsinyear24numberofMLGsidenti edinbothyears).Inbreedingcoef cients(FusingtheGpackage(V4.0.1.0;IS)wereestimatedENEPOPsoftwareRaymondandRousset1995).Totestforgeneticdifferencesinpopulationsbetweensuccessiveyears,analysesofmolecularvariation(AMOVA)werecarriedoutusingtheARLEQUINsoftwarepackage(V3.01;Excof eretal.,2005).AMOVAswerealso

Downloaded from at Queens University of Belfast on January 21, 2011

Page4of8Beatty&Provan—ClonaldiversityinH.monotropa

TABLE1.Numberofplants(N)foundineachpopulationofH.monotropaoversuccessiveyears

N

Bothyears

CountyLocationGridRef.PopulationYear1*Year2 MLGs%inboth

Populationsize§

Co.Antrim

Straidkilly

D297156S176(59)87(82)9540127D297156S249(35)42(34)445748D297156S39(8)3(3)8388D297156S41111001Co.FermanaghCastleCaldwell

H013603CC11–––NCH018605CC26(6)9(7)94411H017605CC310(8)8(5)94410H017605CC42(2)–––NCH024606CC55(4)8(5)5805H025607CC62(2)12502CorrelGlenH074546CG119(4)4259H075546CG21–––NCElyLodge

H176526EL126(23)11(9)243326H176520EL216(15)4(4)152715H181515EL35(5)19(13)152022H184514EL413(13)14(11)138513H184514EL52(2)–––NCH178518EL6–2(1)––NCH181517EL7–1––NCH180515EL8–2(2)––NCKnockninny

H272303

K1

2(1)

–

–

–

NC

Figuresinparenthesesindicatenumberofdistinctmulti-locusgenotypes(MLGs)inpopulationswithmorethanasingleindividual.NC,Notcalculated.

*

2007forCo.Fermanaghpopulations,2009forCo.Antrimpopulations.

2008forCo.Fermanaghpopulations,2010forCo.Antrimpopulations.§

PercentageoftotalMLGsfoundinbothyears.Basedoncapture–recapturecalculation(seeMaterialsandmethods).

TABLE2.Hypopitysmonotropamicrosatelliteprimersdevelopedforthisstudy

LocusRepeatPrimers

SizerangeMHNSSR108(GA)8

ACATTTGGGAAAATGGGAGA130–146bpTTCAATGGCACGTCTTACACAMHNSSR119Complex(GA)GGAAGTTTCTCCATCCAGGTT146–180bpAGCAATCAAAACCAGGACCAMHNSSR135

(AG)8

CGGTTTCAGGAAACAAAACC126–148bp

TTGTCCGGGAATTCTCTCTC

carriedouttodeterminethelevelsofgeneticdifferentiationElyLodgepopulationEL3,andadecreasefrom16tofourbetweenpopulationswithinalocation.

spikesinElyLodgepopulationEL2.

Betweentenand23alleleswere.detectedattheeightmicro-RESULTS

satellitelocianalysed(mean¼1475).AllidenticalMLGshadPGENvaluesof,0.001,con rmingthattheyaroseviaasexualThepresentoccurrenceofHypopitysmonotropainNorthernreproduction.Identi cationofclonematesbasedonidenticalIrelandwouldappeartoberestrictedtofourlocationsinCo.MLGsindicatedthatthelevelsofclonalreproductionwereFermanagh(CastleCaldwell,CorrelGlen,ElyLodgeandgenerallylow,withameanofonly14.45%ofclonalindivid-Knockninny)andonelocationinCo.Antrim(Straidkilly),uals(Table1).IdenticalMLGswerealwayshighlyspatiallyalthoughtheKnockninnypopulationwasnotfoundinthestructuredandgenerallysmall(Figs2and3;alsoseeFigssecondyearofsurveying.ThepopulationrecordedfromS1–S25inSupplementarydataavailableonline).Usually,ErrigalBanks,Co.Londonderrywasnotfoundineitheroftheseinvolvedpairsofclonemateswithin10cmofeachtheyearssurveyedandismostlikelynowextinct.other,althoughlargerclonesweredetected[e.g. verametsPopulationstendedtobeverysmall,generallywithlessthanspanning40cm(StraidkillypopulationS1,2009;Fig.2)andtenspikesperpatch,althoughtwolargepopulationsweretwoidenticalMLGsseparatedby60cmwithnointerveningfoundinStraidkillyinboth2009and2010(Table1).Somespikes(ElyLodgepopulationEL2,2007;Fig.3)].Intotal,notablechangesinpopulationsizewereobservedoversucces-38MLGswererepresentedbytworamets,12bythreesiveyears,includinggrowthfromasinglespiketoninespikesrametsandtwoeachbyfourand veramets.ThepercentageinCorrelGlenpopulationCG1andfrom veto19spikesinofMLGspersistinginapopulationacrossbothyearsof

Downloaded from at Queens University of Belfast on January 21, 2011

Beatty&Provan—ClonaldiversityinH.monotropaPage5of8

10 cm

FIG.2.DistributionofindividualsintheStraidkillyS1,2009population.Dashedlinesenclosemulti-locusgenotypeswhichareidentical.Eachsquarerep-resents10

cm.

andEL4),withmeanvaluesof0.870and0.737inbothyears..LevelsofRcalculatedacrossbothyearsrangedfrom0333(CastleCaldwellpopulationCC5)to0.737(ElyLodgepopulationEL2),withameanvalueof0.552.Theonlysigni -cantdifferenceinH0.596toHEbetweensuccessiveyearswasadropfromHE¼E¼0.417inCastleCaldwellpopulationCC3(two-sidedpairedt-testP¼0.020).TheSpearman’srankcorrelationcoef cientrevealednoassociationbetweenpopu-lationsize(N)andlevelsofHE(rs¼0.289;P¼0.122).Populationsizesbasedonthecapture–recapturecalculationfromMLGsacrossbothyearsrangedfrom1(Straidkillypopu-lationS4)to127(StraidkillypopulationS1).Inbreedingcoef- cients(FIS)rangedfrom0.114(ElyLodgepopulationEL1,2008)to0.813(Castle.CaldwellpopulationCC2,2007),withmeanvaluesof0497and0.339inbothyears.

TheAMOVAanalysesrevealednosigni cantgenetic10 cm

differentiationinpopulationsacrosssuccessiveyears(datanotshown).Signi cantlevelsofgeneticdifferentiationFIG.3.DistributionofindividualsintheElyLodgeEL2,2007population.betweenpopulationswithinlocationsweredetectedin veofDashedlinesenclosemulti-locusgenotypeswhichareidentical.Eachsquare

represents10cm.

thesixanalyses,withbetween7.07%and19.59%ofthetotalobservedvariationexistingbetweenpopulationswithinaregion(Table4).

study(incaseswhereNwasgreaterthan1)rangedfrom20%(ElyLodgepopulationEL3)to85%(ElyLodgepopulationEL4;Table1).

DISCUSSION

Levelsofwithin-populationexpectedheterozygosity(HGeneticdiversityandlevelsofclonalityinperipheralpopulationscalculatedofHypopitysmonotropa

.forpopulationswithN≥5(Table3)rangedfromE)0309(CastleCaldwellpopulationCC2,2007)to0.672(StraidkillypopulationS3,2009),withmeanvaluesof0.507Despiteoccurringinsmall,highlyfragmentedpopulationsinand0.492inbothyears.LevelsofHEcalculatedacrossbothNorthernIreland,Hypopitysmonotropaexhibitedrelativelyyearsrangedfrom0.336(CastleCaldwellpopulationCC2)highlevelsofwithin-populationgeneticdiversity.Theto0.672(StraidkillypopulationS3),withameanvalueofobservedmeanclonaldiversity(R)valueof0.804wasvery0.521.Levelsofclonaldiversity(R)rangedfrom0.571highcomparedwiththeaveragevalueforclonalplants(CastleCaldwellpopulationsCC3andCC5)to1.000(Castle(R¼0.17)reportedbyEllstrandandRoose(1987).ThisCaldwellpopulationCC2andElyLodgepopulationsEL3

gurewasalsoattheupperendoftherangeofmorerecentlypublishedvaluesforunderstoreyherbspecies[0.08,

Uvularia

Downloaded from at Queens University of Belfast on January 21, 2011

Page6of8Beatty&Provan—ClonaldiversityinH.monotropa

TABLE3.Levelsofexpectedheterozygosity(HE)andclonaldiversity(R),andinbreedingcoef cient(FIS)bypopulation

HE

RFIS

Population

Year1*Year2 BothPYear1*Year2 BothYear1*Year2 StraidkillyS10.5830.0.0.9650.5800.4970.StraidkillyS20..540.5660.1060.77305820.1280..5750.8050.0.4190417StraidkillyS3.59105460672NC0.NC.47806360.367NCStraidkillytotal

0..672NC.70808750.8950.CastleCaldwellCC2.6150.0309.56605900.03740.0.121.75610000..551CastleCaldwellCC30.5960..336.75005710.8130.68605710.4710.0.CastleCaldwellCC50..41705840.05250.525.0200.77801420.0..125CastleCaldwelltotal.54505270..750.5710..53003350.3330579ElyLodgeEL10..4970.08330442.51103960.3270..667048908000.0.114ElyLodgeEL2.3840455NC0.NC.8800933NC.6390.0737.1830NCElyLodgeEL30.0..4550.6670.609.50904700.490ElyLodgeEL4.4920.65806480.04350.447.0601.0000569

1.ElyLodgetotal.44704960..0000.0.0.6460898.7690765.4620.6010598Meanbypopulation

0.507

.6000.0492

.5430521

0.870

0.737

0.552

0.497

0.339

OnlypatcheswithN≥5wereanalysed.

NC,Notcalculatedduetosmallsamplesize.

P,Two-tailedpairedt-testprobabilityvaluesfordifferencesinHEbetweenyears.*

2007forCo.Fermanaghpopulations,2009forCo.Antrimpopulations.2008forCo.Fermanaghpopulations,2010forCo.Antrimpopulations.

TABLE4.Analysisofmolecularvariance(AMOVA)forpopulationdifferentiationbylocation

Year1*

Year2

County

Location

%variation

P%variationPCo.AntrimStraidkilly

7..P,0.001Co.Fermanagh

.07P,00019.63CastleCaldwell1677P¼0.07518.ElyLodge

19.59

P,0.001

.76P,0.0011932

P,0.001

*2007forCo.Fermanaghpopulations,2009forCo.Antrimpopulations.2008forCo.Fermanaghpopulations,2010forCo.Antrimpopulations.

perfoliata(Kudohetal.,1999.);0.21,Parisquadrifoliavariationinrange-edgepopulationshasalsobeenreportedin(Jacquemynetal.,2005);033,Convallariakeiskei(Arakiotherclonalplantspecies(Lammietal.,1999;Billinghametal.,2007);0.43,Parisquadrifolia(Jacquemynetal.,etal.,2003;Jumpetal.,2003;Albertoetal.,2006;2006.);0.47,Mercurialisperennis(Vandepitteetal.,2010);Ecksteinetal.,2006).

083,Trilliumcuneatum(Gonzalesetal.,2008);0.84,ClonesinH.monotropaweresmall,extendingatmostoverAnemonenemorosa(Rusterholzetal.,2009);0.93,Violaafewtensofcentimetres.Inmostcases,theywerepairsofriviniana(Augeetal.,2001)].Thesehighlevelsofdiversityverycloselyspaced,adjacentMLGsasfoundinpreviousareinstarkcontrasttothoseobservedinOrthiliasecunda,studiesonotherclonalplantspecies(Haradaetal.,1997;anothermemberoftheMonotropoideaethatisrestrictedtoHoldereggeretal.,1998;Suzukietal.,2006).Inaddition,thesametwolocationsinNorthernIreland.ApreviousidenticalMLGswereneverfoundinterspersedwithotherstudyonthisspecies(Beattyetal.,2008)revealedthateachMLGs.Thus,themodeofclonalspreadinH.monotropapopulationcomprisedasingleclone.Bothspeciescurrentlywouldappeartoconformtothe‘phalanx’dynamic,whereexistinhighlyfragmentedpopulationsattheedgeoftheirclonesarecharacterizedbycompactgrowthforms,ratherrangesinthesameareasinNorthernIreland,butthanthe‘guerrilla’pattern,wherelongerrhizomesareinter-H.monotropaisprimarilyatemperatespecieswhereasmingled,givingrisetoclustersofdifferentramets(LovettO.secundagenerallyhasamoreborealdistribution.ItisDoust,1981;HumphreyandPyke,1998).Thesesmallclonesthuspossiblethatclimaticfactorshavein uencedtheswitchareagainincontrasttothoseobservedpreviouslyintoextensiveclonalgrowthinthelatterspecies.O.secunda,whereseverallargemonoclonalpatcheswereNevertheless,althoughH.monotropaexhibitedfarhigherfound,includingonecomprisedofapprox.600individualsdiversitythanO.secundainNorthernIreland,levelsofcoveringanareaofapprox.300m2(Beattyetal.2008).expectedheterozygosityweresigni cantlylowerthanthoseFurthermore,populationsofH.monotropainthepresentcalculatedfrompopulationsinthemainpartofthespecies’studydidnotappeartobecomposedoftheentirelysamedistributionrangeinEurope(Mann-WhitneyU-testP¼clonesacrossbothyearsofstudy,althoughtheoverall0.002;BeattyandProvan,2011).Suchadecreaseingenetic

geneticdifferencebetweenyearswasnon-signi cant.

Downloaded from at Queens University of Belfast on January 21, 2011

Beatty&Provan—ClonaldiversityinH.monotropa

Page7of8

TheobservedlowlevelsofclonalitysuggestthatmostgenetsinthepopulationsofH.monotropastudiedarefertileandthatreproductionispredominantlysexual.Theobservedlevelsofinbreeding,however,werehighinalmostallofthepopulationsstudied.ApreviousstudyonthereproductiveecologyofthegenusMonotropaandtherelatedgenusMonotropsisidenti eddifferencesinlevelsofautogamousseedsetinthetwocolourmorphsofH.monotropathatarefoundinNorthAmerica(KloosterandCulley,2009).Boththeredandyellowforms(theyellowformbeingthemorphfoundinBritainandIreland)werehighlyself-compatible,butonlytheyellowformsetsubstantialamountsofautoga-mousseedafterself-pollination.Thus,itislikelythatthehighlevelsofinbreedingobservedinthepopulationsinthepresentstudyaretheresultofself-pollination,particularlygiventhesmallnumbersofindividualsinmostofthepatches.Beingself-compatible,however,meansthatH.monotropadoesnotfacethesameproblemsofcompletelossofsexualreproductionand/orrapidpopulationextinctionthatcanthreatenpopulationsofobligatelyoutcrossingclonalplants.Wheremateavailabilityislimitedinsuchspecies,orwherepopulationsarecomprisedofasmallnumberoflargeclones,manyofwhichareoftenrelated,self-incompatibiltymechanismsandstigmasaturationviaself-pollinationcanleadtosexualreproductivefailureandsubsequentextensivelossofgeneticvariation(e.g.Willietal.,2005;ScobieandWilcock,2009).Nevertheless,ongoinginbreedingremainsapotentialthreattothefragmented,peripheralpopulationsinvestigatedinthepresentstudy.

Conservationimplications

Inthepresentstudy,thetransientnatureofH.monotropawasnotedatboththepopulationlevelandattheindividuallevelwithinpopulations.Evenlargepopulationshavebeenobservedtodisappearwithinafewyears(LocktonandWalker,2010),whichposesaproblemwhentryingtoestimatecensusnumbersforthespecies,astheactualnumbersofindi-vidualswillnotbetrulyknownifasurveywascarriedoutinanysingleyear.Furthermore,anadditionalissuewhenattemptingtoidentifycensusnumbersforH.monotropaistheincidenceofclonalgrowth.Asaerialspikesdonotnecess-arilyrepresentseparategenets,theymayinfactrepresentmul-tiplerametsofthesamegenet.Geneticanalysesoversuccessiveyearsthereforeprovidevitalinformationonthedynamicsofthesethreatenedpopulations.Althoughthepresentstudyonlyconsidereda2-yearperiodateachlocation,nosigni cantdifferenceswereobservedingeneticdiversityorcompositionofthepopulationsbetweensuccessiveseasons,withtheexceptionofasingledecreaseindiversityinonepopulation.GiventhehighlevelsofinbreedinginNorthernIreland’sremainingpopulationsofH.monotropa,however,furthergeneticmonitoringwouldbeadvisabletoensurethatgeneticdiversityismaintained.Iflevelsofgeneticdiversityweretodroptotheextentthatsomeformof‘geneticrescue’isrequired,thenthegeneticdistinctnessbetweenpopulationsrevealedbytheAMOVAanalysesshouldbetakenintoaccount,bothintermsofpossiblymaximizinggeneticdiver-sity,butstillconsideringthepotentialforoutbreedingdepression(Frankham,2010).Furthermore,thesmalland

fragmentednatureofremnantpopulations,withlownumberscon rmedbythecapture–recapturecalculationacrosssucces-siveyears,leavesthemvulnerabletostochasticextinctionevents.

SUPPLEMENTARYDATA

andconsistof25distributionmapsofindividualswithineachpopulation.

ACKNOWLEDGEMENTS

WeareextremelygratefultoRobertandHannahNorthridgeforprovidingtheCo.Fermanagh2007samples,RobertBeattyforassistancewithsampling,RalphForbesforhelpfuldiscussions,andNeilReidforGISadvice.Wearealsogratefultothreeanonymousrefereesforcommentswhichgreatlyimprovedthemanuscript.Thisresearchwassup-portedbyaPhDstudentshipawardedtoGemmaBeattybytheDepartmentofAgricultureandRuralDevelopment,NorthernIreland.

LITERATURECITED

AlbertoF,Arnaud-HaondS,DuarteCM,SerraoE.2006.Geneticdiversity

ofaclonalangiospermnearitsrangelimit:thecaseofCymodoceanodosaintheCanaryIslands.MarineEcologyProgressSeries309:117–119.

ArakiK,ShimataniK,OharaM.2007.Floraldistribution,clonalstructure,

andtheireffectsonpollinationsuccessinaself-incompatibleConvallariakeiskeipopulationinnorthernJapan.PlantEcology189:175–186.

Arnaud-HaondS,BelkhirK.2007.GeneClone:acomputerprogramto

analysegenotypicdata,testforclonalityanddescribespatialclonalorganization.MolecularEcologyNotes7:15–17.

AugeH,NeufferB,ErlinghagenF,GrupeR,BrandlR.2001.Demographic

andrandomampli edpolymorphicDNAanalysesrevealhighlevelsofgeneticdiversityinaclonalviolet.MolecularEcology10:1811–1819.BeattyGE,parativephylogeographyoftworelatedplant

specieswithoverlappingrangesinEurope,andthepotentialeffectsofclimatechangeontheirintraspeci cgeneticdiversity.BMCEvolutionaryBiology,inpress.

BeattyGE,McEvoyPM,SweeneyO,ProvanJ.2008.Range-edgeeffects

promoteclonalgrowthinperipheralpopulationsoftheone-sidedwinter-green(Orthiliasecunda).DiversityandDistributions14:546–555.BidartondoMI,BrunsTD.2001.Extremespeci cityinepiparasitic

Monotropoideae(Ericaceae):widespreadphylogeneticandgeographicstructure.MolecularEcology10:2285–2295.

BillinghamMR,ReuschTBH,AlbertoF,SerraoEA.2003.Isasexual

reproductionmoreimportantatgeographicallimits?AgeneticstudyoftheseagrassZosteramarinaintheRiaFormosa,Portugal.MarineEcologyProgressSeries265:77–83.

BooyG,HendriksRJJ,SmuldersMJM,vanGroenendaelJM,VosmanB.

2000.Geneticdiversityandthesurvivalofpopulations.PlantBiology2:379–395.

BrownJH.1984.Ontherelationshipbetweenabundanceanddistributionof

species.AmericanNaturalist124:255–279.

CaughleyD,GriceD,BarkerR,BrownB.1988.Theedgeofrange.Journal

ofAnimalEcology57:771–785.

EckertCG.2002.Thelossofsexinclonalplants.EvolutionaryEcology15:

501–520.

EckertCG,SamisKE,LougheedSC.2008.Geneticvariationacrossspecies’

geographicalranges:thecentral-marginalhypothesisandbeyond.MolecularEcology17:1170–1188.

EcksteinRL,O’NeillRA,DanihelkaJ,OtteSA,Ko

¨hlerW.2006.Geneticstructureamongandwithinperipheralandcentralpopulationsofthreeendangered oodplainviolets.MolecularEcology15:2367–2379.

Downloaded from at Queens University of Belfast on January 21, 2011

Page8of8Beatty&Provan—ClonaldiversityinH.monotropa

EllstrandNC,RooseML.1987.Patternsofgenotypicdiversityinclonalplant

species.AmericanJournalofBotany74:123–131.

Excof erL,LavalLG,SchneiderS.2005.ARLEQUIN,Version3.0:aninte-gratedsoftwarepackageforpopulationgeneticdataanalysis.EvolutionaryBioinformaticsOnline1:47–50.

FrankhamR.2010.Challengesandopportunitiesofgeneticapproachesto

biologicalconservation.BiologicalConservation143:1919–1927.

GonzalesE,HamrickJL,parisonofclonaldiversity

inmountainandpiedmontpopulationsofTrilliumcuneatum(Melanthiaceae-Trilliaceae),aforestunderstoryspecies.AmericanJournalofBotany95:1254–1261.

HampeA,PetitRJ.2005.Conservingbiodiversityunderclimatechange:the

rearedgematters.EcologyLetters8:461–467.

HaradaY,KawanoS,IwasaY.1997.Probabilityofclonalidentity:inferring

therelativesuccessofsexualversusclonalreproductionfromspatialgeneticpatterns.JournalofEcology85:591–600.

HoldereggerR,StehlikI,SchellerJJ.1998.Estimationoftherelativeimpor-tanceofsexualandvegetativereproductionintheclonalwoodlandherbAnemonenemorosa.Oecologia117:105–107.

HonnayO,BossuytB.2005.Prolongedclonalgrowth:escaperouteorroute

toextinction?Oikos108:427–432.

HumphreyLD,PykeDA.1998.Demographicandgrowthresponsesofa

guerrillaandaphalanxperennialgrassincompetitivemixtures.JournalofEcology86:854–865.

JacquemynH,BrysR,HonnayO,HermyM,Roldan-RuizI.2005.Local

forestenvironmentlargelyaffectsbelow-groundgrowth,clonaldiversityand ne-scalespatialgeneticstructureinthetemperatedeciduousforestherbParisquadrifolia.MolecularEcology14:4479–4488.

JacquemynH,BrysR,HonnayO,HermyM,Roldan-RuizI.2006.Sexual

reproduction,clonaldiversityandgeneticdifferentiationinpatchilydis-tributedpopulationsofthetemperateforestherbParisquadrifolia(Trilliaceae).Oecologia147:434–444.

JumpAS,WoodwardFI,BurkeT.2003.Cirsiumspeciesshowdisparityin

patternsofgeneticvariationattheirrange-edgedespitesimilarpatternsofreproductionandisolation.NewPhytologist,160:359–370.

KloosterMR,parativeanalysisofthereproductive

ecologyofMonotropaandMonotropsis:twomycoheterotrophicgeneraintheMonotropoideae(Ericaceae).AmericanJournalofBotany96:1337–1347.

KloosterMR,HoenleAW,CulleyTM.2009.Characterizationofmicrosatel-litelociinthemyco-heterotrophicplantMonotropahypopitys(Ericaceae)andampli cationinrelatedtaxa.MolecularEcologyResources9:219–221.

KudohH,ShibaikeH,TakasH,WhighamDF,KawanoS.1999.Genet

structureanddeterminantsofclonalstructureinatemperatedeciduouswoodlandherb,Uvulariaperfoliata.JournalofEcology87:244–mmiA,SiikamakiP,MustajarviK.1999.Geneticdiversity,population

size,and tnessincentralandperipheralpopulationsofarareplantLychnisviscaria.ConservationBiology13:1069–1078.

LeakeJR,McKendrickSL,BidartondoM,ReadDL.2004.Symbioticger-minationanddevelopmentofthemyco-heterotrophMonotropahypopitysinnatureanditsrequirementforlocallydistributedTricholomaspp.NewPhytologist163:405–423.

LesicaP,AllendorfFW.1995.Whenareperipheralpopulationsvaluablefor

conservation?ConservationBiology9:753–760.

LhullierE,ButaudJ-F,BouvetJ-M.2006.Extensiveclonalityandstrong

differentiationintheinsularPaci ctreeSantaluminsulare:implicationsforconservation.AnnalsofBotany98:1061–1072.

LocktonAJ,WalkerKJ.2010.Speciesaccount:Monotropahypopitys.

BotanicalSocietyoftheBritishIsles..uk/LovettDoustL.1981.Populationdynamicsandlocalspecializationina

clonalperennial(Ranunculusrepens).I.Thedynamicsoframetsincon-trastinghabitats.JournalofEcology69:743–755.

ParksJC,WerthCR.1993.Astudyofspatialfeaturesofclonesinapopu-lationofbrackenfern,Pteridiumaquilinum(Dennstaedtiaceae).AmericanJournalofBotany80:537–544.

ProvanJ,WilsonPJ.2007.Developmentofmicrosatellitesforthepeatmoss

SphagnumcapillifoliumusingISSRcloning.MolecularEcologyNotes7:254–256.

RaymondM,RoussetF.1995.GENEPOP(version1.2):populationgeneticsoft-wareforexacttestsandecumenicism.JournalofHeredity86:248–249.RusterholzHP,KisslingM,BaurB.2009.Disturbancesbyhumantrampling

altertheperformance,sexualreproductionandgeneticdiversityinaclonalwoodlandherb.PerspectivesinPlantEcology,EvolutionandSystematics11:17–29.

ScobieAR,WilcockCC.2009.Limitedmateavailabilitydecreasesreproduc-tiovesuccessoffragmentedpopulationsofLinnaeaborealis,arare,clonalself-incompatibleplant.AnnalsofBotany103:835–846.

ShumakerKM,BabbleGR.1980.Patternsofallozymicsimilarityineco-logicalcentralandmarginalpopulationsofHordeumjubatuminUtah.Evolution34:110–116.

SilvertownJ.2008.Theevolutionarymaintenanceofsexualreproduction:

evidencefromtheecologicaldistributionofasexualreproductioninclonalplants.InternationalJournalofPlantSciences169:157–168.SmithS,HughesJ,Wardell-JohnsonG.2003.Highpopulationdifferen-tiationandextensiveclonalityinararemalleeeucalypt:Eucalyptuscur-tisii.ConservationGenetics4:289–300.

Soule

´M.1973.Theepistasiscycle:atheoryofmarginalpopulation.AnnualReviewofEcologyandSystematics4:165–187.

SuzukiJ,HerbenT,KrahulecF,Storchova

´H,HaraT.2006.EffectsofneighbourhoodstructureandtussockdynamicsongenetdemographyofFestucarubrainamountainmeadow.JournalofEcology94:66–76.TybjergH,VestergaardP.1992.Growthdynamicsintherhizomatous

Polygonatumverticillatum.Oikos65:395–408.

VandepitteK,HonnayO,deMeyerT,JacquemynH,Roldan-RuizI.2010.

PatternsofsexratiovariationinthedioeciousforestperennialMercurialisperennis.PlantEcology206:105–114.

VucetichJA,WaiteTA.2003.Spatialpatternsofdemographyandgenetic

processesacrossthespecies’range:nullhypothesesforlandscapeconser-vationgenetics.ConservationGenetics4:639–645.

WallaceGD.1975.StudiesoftheMonotropoideae(Ericaceae):taxonomyand

distribution.WassmanJournalofBiology33:1–88.

WallaceGD.1977.StudiesoftheMonotropoideae(Ericaceae).Floralnectar-ines:anatomyandfunctioninpollinationecology.AmericanJournalofBotany64:199–206.

WilliY,vanBuskirkJ,FischerM.2005.Athreefoldgeneticalleeeffect:

populationsizeaffectscross-compatibility,inbreedingdepressionanddriftloadintheselfincompatibleRanunculusreptans.Genetics169:2255–2265.

Downloaded from at Queens University of Belfast on January 21, 2011

本文来源：https://www.bwwdw.com/article/494m.html