DAHLIA SUBLIGNOSA (ASTERACEAE): A SPECIES IN ITS OWN RIGHT

2005·2.6 MB·English

by  Dayle E Saar

DAHLIASUBLIGNOSA(ASTERACEAE):
ASPECIESINITSOWNRIGHT
DayleE.Saar^ Paul D.S0rensen
DepartmentofBiologicalSciences DepartmentofBiologicalSciences
MurrayStateUniversity NorthernIllinoisUniversity
MurrayKentucky42071,U.S.A. DeKalb.Illinois60115,U.S.A.
ABSTRACT
Dahliadissectavar.suhlignosawasrecognizedin1969basedonavailableherbariumspecimens.Here
wepresentmolecularevidencetodemonstratethatvarsuhlignosaisnotthesistertaxontoD.dissecta
var.dissecta,norisitconspeciticwitheitherofitstwoclosestallies,D.lineariss^ndD.JoeniculiJoUa.
Therefore,weelevateDahliadissetlavarsuhlignosatotherankofspecies,asD.suhlignosa(RD,
Sorensen)D.H.Saar&P.D.Sorensencomb,&stat,nov.
RESUMEN
Dahhadissectavarsuhlignosasereconocioen1969basandoseenloscspecimenesdeherbario
disponibles,Presentamosaquiunapruebamolecularparadcmostrarquevar.suhlignosanoeseltaxon
hermanodeD.dissectavardissecta,niesconspecificoconningunodesusdossemejantesmas
proximos,D.linearisyD.foeniculijolia.Forello,elevamosDahliadissectavar.suhlignosaalrangode
especie,asicomoD.suhlignosa(P.D.Sorensen)D.E.Saar&P.D.Sorensencomb.&stat.nov
INTRODUCTION
DahliadissectaS.Watsonpresentlyhastworecognizedintraspecifictaxa:D.
dissectavardissectaandD.dissectavarsuhlignosaP.D.Sorensen.Dahliadissecta
isinsect.Entemophyllon,v/hichincludesfiveotherspecies.Dahliadissectavar.
dissectaisknownfromrockyslopesandledgesintheMexicanstatesofHidalgo
andSanLuisPotosi,atelevationsof1900-2500m.Whilenotcommon,plants
arenotdifficulttofindintheseareas.Varietysuhlignosaisknownonlyfrom
thetypelocalityandanearbylocationmwesternTamaulipas,Mexico,atel-
evationsof2100-2500m.Therangesforthesetwovarietiesareseparatedby
about137kmattheirclosestpoint,andvar.suhlignosaisnotsympatricwith
anyothertaxainsect.Entemophyllon.
Dahliadissectavardissectawasconservativelydescribedbasedonlim-
itedherbariumspecimensknownatthetime(Sorensen1969).Morphologically,
thetwotaxaareverysimilar,atleastsuperficially.Bothhaveultimateleafseg-
mentsthatcloselyresembleeachotherinshape.Allofthespeciesinsect.
Entemophyllondescribedatthetimehadsubstantialperennatmgstemsexcept
D.dissecta,whichiswhollyherbaceous.Varietysuhlignosaisminimallywoody
atthebaseofthecanes.
Authorforcorresponderice;e-mail:dayle.saar@nnurraystate,edu
SIDA21(4):2161-2167.2005
2162 BRIT.ORG/SIDA21(4)
ThevarietiesdifferinthatD.dissectavar.sublignosatendstobelarger,
reachingheightsof7-9dmcomparedto3-7.6dmforvardissecta.Stemsofthe
currentyearsgrowtharisedirectlyfromacrownoftubersorrootstockonvar
dissecta,whereasstemsofvdv.sublignosafrequentlyarisefromshort(5-15cm)
ligneousportionsoi thepreviousyear'sgrowth.Theleavesofvarsublignosa
canbealittlelonger(11-19vs.10-15cm),withsometimessmallerultimateseg-
ments(0.5-5.5vs.2-9mm).Outerinvolucralbractsare2.5-5.5mmmwidthfor
var.sublignosaand1.8-4mmforvardissecta(Sorensen1969).Perhapsthemost
distinctiveieatureotdifterenceisthesquarish,cusp-tippedleaf segmentsof
var.sublignosa,ascomparedtomorerounded leafsegmentsonvar.dissecta,
whichmayormaynothaveasmallercusp(seeFig.la-b).
Observationsmadewithrecentlycollectedlivematerialsuggestedmore
differencesbetweenthevarietiesthancanbeseenwithherbariumspecimens
alone.Therelore,amolecularanalysiswasconductedtoclarifytherelation-
shipofthesetwopresumedintraspecifictaxa.
MATERIALSANDMETHODS
Liveplantmaterialv/asobtainedfromPlantDelightsNursery,Inc.,Raleigh,NC,
whichoriginatedasseedfromYuccaDoNursery,Hempstead,TX,accession
numberD07-615,collectedmtheCerroPeiiaNevadaMountains,inthevicin-
ityofthetypelocality.D.E.Saar3521,3522(MUR).
PlantsofDahliadissectavarsublignosafloweredinanoutdoorplot,which
providedmaterialforchromosomecountsfrompollenmothercellsindevel-
opingcapitula.HeadsofappropriatesizewerefixedinmodifiedCarnoyssolu-
tion(4:3Tv/vofchloroform:absoluteor95%ethanol:glacialaceticacid),trans-
lerrcdto70%alcohol,andstoredat4°Cuntilthechromosomeswerecounted.
ThestainingprocedureissummarizedmSaar(1999).
LeafmaterialwascollectedIromtwogreenhouseplantsofDahliadissecta
var.sublignosaandoneplantofDahliafoeniculijoliaSherffatMurrayState
University.DNAwasextractedusingaDNeasy®PlantMiniKit(Qiagenno.
69104).Theinternaltranscribedspacerregions(ITS)ofnuclearribosomalDNA
wereamplifiedusingforwardprimerlTS5m(Sangetal.1995)topreventacci-
dentalamplificationofendophyticfungi,ifpresent(Saaretal.2001),andre-
verseprimerITS4(Whitectal.1990).Reactionswerem50|uLvolumesandcon-
tained2unitso(Taqpolymerase(Promega,Madison,Wl),0.2mMofeachdNTP
O.luMofeachprimer,and75ngof template.Amplificationwascarriedouton
anMJResearchthermalcyclerPTO200usingtheloUowingprotocol:onecycle
of2min30secat95°C,30secat50°C,andonemmat72°C.;followedby30
cyclesol 30secat95°C,oneminat50°C,andonemmat72°C;andfinished
with6mmat72°C.Amplifiedproductsv/ererunon1.0%^agarosegelsusing0.5x
TBEanddetectedwithethidium-bromidefluorescenceonaUVtransillumina-
tonProductswerecleanedforsequencingusingMicrocon®CentrifugalFilter
SAARANDS0RENSEN,DALIASUBLIGNOSA 2163
FigJ.Comparativeleafshapesfromgreenhouse-grownplants:A.DflW/fliuW/gnosa(formerlyarf/5jerfflvar.5oW/gnosa^^^
B.Dahliadissecta(var.dissecta);C.Dahlialinearis;D.Dahliafoeniculifolia.Leavesfromthesegreenhouseplantsare
representativeofwild-grow/nplantsingeneralshapebutaresmallerinsizeandnotproportionaltoeachotheras
suggestedhere.Seetextforleafdimensionsofwild-collectedplants.
Devices(YM-100)fromMillipore(Bedford,MA).SequencingwasonaBeckman-
Coultercapillarysequencer.Thisprocedurewasperformedtwiceforvar.
suhlignosa,beginningwiththeDNAextractionfromfreshleaves.Oursequence
forD.dissectavandissecta(Saaretal.2003)iscongruentwiththesequenceof
var.dissectaobtainedbyGattetal.(2000),sorepeatmgtheprocedureforthis
taxonwasdeemedunnecessary.
ITSsequencesfromthreespeciesinsect.Entemophyllonweredownloaded
fromGenBank(Saaretal.2003).Materialfromtheremainingspeciesinthe
section,DahliacongestijohaP.D.Sorensen,wasnotavailable,asitisknownonly
fromthetypespecimen.Duringfieldworkin1995,wetwicesearchedtheW-
facingslopesofthesomewhatisolated,smalllimestonemountainofCerro
Chulconear ApaninextremesouthernHidalgo, the type localityofD.
congestijoha,butfailedtorelocatethisspecies.Twootherunsuccessfulsearches
weremadesubsequenttothecollectionofthetypebutpriortoitsformalrec-
ognition(Sorensen1987).DahliamerckiiLehm.wasusedastheoutgrouptaxon
basedonSaaretal.(2003)anditssequencewasalsoobtainedfromGenBank
(Table1). W
SequenceswerealignedwithClustal software(alignmentavailableon
request).Nogapswereneededtoaligntheingrouptaxa;threeone-basegaps
wererequiredtoaligntheingroupwiththeoutgrouptaxon.Theywereignored
intheanalysis.Singlebasepolymorphismsarelimitedtoone(r)inDahlia
2164 BRIT.ORG/SIDA21(4)
Tablel.GenBankAccessionNumbers.
Species GenBankAccessionNo. Source
DahliadissectaS.Walson AYn7465 Saaretal.2003
DahliafoeniculifoliaSherff AYl17466 Saaretal.2003
DahlialinearisSherff AYl17467 Saaretal.2003
Dahliamerckiilehm. AYl17471 Saaretal.2003
DahliarupicolaP.D.Sarensen AYl17468 Saaretal,2003
DahliascapigeroidesSherff AYl17469 Saaretal.2003
Dahliasublignosa(RD.Ssrenseri)Saar&RD,SorenserT DQl98259 thisstudy
linearisShcr[[andtwo(y,s)mD.scapigeroidesSherli,whichwereincludedm
thematrixlormatsymbolsforanalysis.Abranch-and-boundsearchwasper-
formedusingPAUP*4.0v8(Swofford1998)onaMacmtoshG5computer.Boot-
strapanalysis(Felsenstein1985)wasperformedusing1000replicates.Pairwise
distancesluncorrected("p")distancematrix]werecalculatedwithPAUP
RESULTS
TheITSsequencesforbothplantsofDahliadissectavar.sublignosaareidenti-
cal,soonlyonesequencewassubmittedtoGenBank.Thenewsequenceob-
tainedforD.foeniculifoHaisconsistentwiththatofSaaretal.(2003)butisof
betterquality(nounknownsorpolymorphisms),presumablyduetotheavail-
abihtyotbetterleafmaterialfromthesameplant(GenBanksequenceupdated).
Thephylogeneticanalysisproducedtwotreesofashortestlengthof70
steps(CI0.971,Rl0.917,RC0.890,HI0.029).Atotalof671l^asepairswerealigned
andanalyzed:251bpinlTS-1,220bpinITS-2,andtheremainingbpfromflank-
ingregionsofcodingnrDNA.
ResultsshowthatthesistertaxontoDahliadissectavar.sublignosaisnot
var.dissectabuteitherD.linearisorD.Joeniculifolia.ThetreeshowninFigure
2,basedonastrictconsensus,resultsinapolytomybetweenD.linearis,D.
foeniculifolia,andthetwosamplesofvar.sublignosa.
Adistancematrixofsect.Entemophyllon hasanaverageof1.54%(5=
0.0066)sequencedivergenceamongthesixtaxa.Dahliadissectavar.sublignosa
differsfromD.linearisby0.91%andfromD.Joeniculifoliaby1.21%.
Thechromosomenumberisn=17.
DISCUSSION
ThephylogeneticanalysisshowsthatDahliadissectavar.dissectaandvar.
sublignosaarenotconspecific.LeafandflowermorphologyandITSsequences
alsodonotsuggestthatitisavarietyofthenextclosesttaxa,D.linearisorD.
Joeniculijolia(Fig.1).ThesequencedivergencesbetweenvarsublignosaandD.
SAARANDS0RENSEN,DALIASUBLIGNOSA 2165
99 (45) (5) D.disssectavandissecta
(5) D.scapigeroides
100 (5) D.foeniculifolia
OCS {^) (3) D.linearis
97 (50) 99 (3) (0) D.sublignosa(plantA)
(0) D.sublignosa(plantB)
(2) D.rupicola
D.merckii
Fig.2.PhylogeneticanayisisofDahliasect.EntemophyllonusingITSsequences.OutgroupisD.merckii(notinsect.
Entemophyllon).Numbersabovebranchesrepresentbootstrapvalues;numbersinparentiiesisindicatenumberof
changes.
linearisandbetweenvar.sublignosaandD.foeniculifolia(0.91and1.21%,re-
spectively)areconsistentwiththeotherspeciesinthesectionandotherclades
inthegenus.Bycomparison,the"variablerootclade"(Saaretal.2003)averages
0.97%(5=0.0087)divergencefor10taxaandthe"coreDahliaclade"(Saaretal.
2003)averages0.87%(5=0.0096)over15taxa.Therefore,itisconcludedthatD.
dissectavar.sublignosashouldbeelevatedtotherankofspecies,coordinatewith
theothertaxaofthesection:
Dahliasublignosa(P.D.Sorensen)D.E.Saar&P.D.Sorensen,comb.&stat.nov
(Fig.3).TypI::MEXICO.Tamaulipa.s:4.8kmNofMicjuihuanainforestdominatedbyPnius
(99°47'NLat;23°36'WLong),elev.ca.2100m,14Jul1949,Stanjord,Taylor.&Lauber2436
(HOLOTYPE:NY;ISOTYPES:GH,MICH,TEX.UC,US-2,WTU).
Dahliasublignosa isreadilydistinguished fromeither D.linearisorD.
foeniculifoliabyitsshorterultimateleafsegments(0.5-5,5mmvs,9-23forD,
linearisand30-55mmforD.foeniculifolia).Thechromosomenumberofn=17
isconsistentwithfiveoftheotherspeciesinthesection;thenumberisnot
knownforthesixthspecies,Dahliacongcstifolia.
TheelevationofDahliasublignosatorankofspeciesbringsthenumberof
"wild"speciesinthegenusto36,butdoesnotincludethecultivatedformsof-
tencalledD.variabilisDesf.oroccasionallyD.pinnataCav,butseeHansen
andHjerting(1996)forclarificationofthelatterbinomial.
ACKNOWLEDGMENTS
WethankCourtneyA.ThomasonforpreparingthelinedrawingofDahlia
sublignosa.WearegratefultothefolksatPlantDelightsNursery,Raleigh,NC,
forgenerouslysupplyinguswithlivingmaterialofDahliasublignosa.Guy
NesomandRichardNoyesprovidedhelpfulcommentsforanearlierversionof
themanuscript.
2166 BRIT.ORG/SIDA21(4)
(^^wCUm-3^;'^'^^aa>^
Fig.3.FlowerheadaiDahliasublignosa.Scalebarrepresents1cm.
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