High clonal diversity in threatened peripheral populations o

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

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Page2of8Beatty&Provan—ClonaldiversityinH.monotropa

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

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

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