Global Ecol Biogeogr. 2018;1–13. wileyonlinelibrary.com/journal/geb  | 1© 2018 John Wiley & Sons Ltd

Received:11May2018  |  Revised:25September2018  |  Accepted:2October2018DOI:10.1111/geb.12862

R E S E A R C H P A P E R

Naturalized distributions show that climatic disequilibrium is structured by niche size in pines (Pinus L.)

Daniel L. Perret  | Andrew B. Leslie | Dov F. Sax

DepartmentofEcologyandEvolutionaryBiology,BrownUniversity,Providence,RhodeIsland

CorrespondenceDanielL.Perret,DepartmentofEcologyandEvolutionaryBiology,BrownUniversity,Providence,RI02912.Email:daniel_perret@brown.edu

Editor:AdrianaRuggiero

AbstractAim:Theassumptionthatthenativedistributionsofspeciesareinequilibriumwithclimatehasbeenshowntobefrequentlyviolated,despiteitscentralitytomanynichemodel applications.Wecurrently lack a framework that predicts these violations.Here,weexaminewhethervariationinclimaticdisequilibriumisstructuredbyprop-ertiesofspecies’nativedistributionsandclimaticniches.Location: Global.Methods:Webuiltclimaticnichemodelsfor106pine(PinusL.)species,including25thathavenaturalizedoutsidetheirnativerange.Wemeasuredtheextentofclimatespaceoccupiedexclusivelybynaturalizedpopulationsandconsideredwhatfractionofthisspacewasavailablewithinthenativecontinentandnearthenativerange.Weexaminedtheconsequencesofdisequilibriumforestimatesofpotentialrangefillingandsisterspeciesnicheconservatism.Results:Mostspecies(23of25)havenaturalizedinclimateconditionsoutsidethenativeniche,leadingtoincreasesinthetotalknownsuitableclimatespace.Increasesinnichesizewerenegativelyrelatedtonativenichesize.Increaseswereoftenlarge;onespeciesexpandeditsnichebyalmost10%oftheglobalclimatespace.Thesein-creases were associated primarily with cooler, wetter and less seasonal climates.Increasesinknownnichesizeloweredpotentialrangefillingestimateswithinspecies’native continent and ecoregion. Naturalized data did not strengthen support fornicheconservatismamongsisterspecies.Main conclusions:Amongpines,climaticdisequilibriumisthenormandnottheex-ception.Themagnitudeofthisdisequilibriumcanbevast,suchthatthenativerangegreatlyunder‐representsthetrueclimatictolerancesofsomespecies.Fortunately,this disequilibrium canbe predicted largely by the size of a species’ native niche.Accountingforthisdisequilibriumcanimproveourabilitytocharacterizeecologicalphenomena, includingpotential range filling.This is anessential step towards im-provingtheconservationvalueofecologicalnichemodels.

K E Y W O R D S

climatechange,conservationplanning,ecologicalnichemodel,nichesize,phylogeneticnicheconservatism,rangefilling,treeinvasions

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1  | INTRODUC TION

Speciesdistributionmodels (SDMs)andtheecologicalnichemod-els (ENMs) thatunderlie themare important toolsused topredictspeciesinvasions(e.g.,Broennimannetal.,2007;Guisan,Petitpierre,Broennimann,Daehler, & Kueffer, 2014; Peterson, 2003; Thuiller,Richardson, et al., 2005), estimate extinction risk under climatechange (e.g., Thuiller, Lavorel, Lavorel, Araújo, Sykes, & Prentice,2005) and inform conservation planning (e.g., Early & Sax, 2011;Williamsetal.,2005).Aprimaryassumptionofthesemodels,thatspeciescansurviveonlyinareaswithclimaticconditionsmatchingthosewheretheycurrentlyoccur(Busby,1988),hasbeenrecognizedsincethereleaseofthefirstwidelyusedSDMpackage(BioClim;Nix,1986;Booth,Nix,Busby,&Hutchinson,2014).Thecurrentformu-lationofthisassumption,thatspeciesdistributionsexistinequilib-riumwiththeirnativeclimate(i.e.,speciesoccurinalltheclimatesthatcouldsustainthem),hasbeenshowntobefrequentlyviolated(Booth et al., 2015; Booth, Nix, Hutchinson, & Jovanovic, 1988;Boscietal.,2016;Early&Sax,2014;Gallagher,Beaumont,Hughes,&Leishman,2010).Climaticdisequilibriumcanresultfromdispersallimitations, biotic interactions or contingencies of biogeographicalhistory(Svenning&Skov,2004;Wiszetal.,2013),allofwhichcanconstraintherealizednichetoanestedsubsetofthefundamentalniche.Here,wedefinetherealizednicheastheclimatespaceoccu-piedbythespecies’historicalnativerange.Wedefinethefundamen-talnicheastheclimatespaceinwhichaself‐sustainingpopulationcanbemaintained,butwhichmaynotbe fullyoccupiedowing toantagonisticbiotic interactions,missingpositivebiotic interactionsorbarrierstodispersal(Sax,Early,&Bellemare,2013).

Models that incorporateonly realizedconditionswill generallyunderestimate invasion risk (Broennimann & Guisan, 2008) andoverestimatethesensitivityofspeciestochangesinclimate(Araújoetal.,2013).Thismismatchbetweenrealizedandfundamentalnichespacecouldbeamelioratedbybuildingmodelsthat includeempir-ical informationonthefundamentalniche.However, this informa-tionisgenerallyunavailableformostspecies.Likewise,nopredictiveframeworkexiststoestimateormodelfundamentalnicheconditionsreliablyrelativetorealizedconditions(Saxetal.,2013),althoughre-centworkpairingcriticalphysiologicallimitswithrealizednichees-timateshasmadeprogress inthisregard(Soberón&Arroyo‐Peña,2017).Withoutsuchaframework,itisdifficulttoknowhowmuchconfidenceweshouldplaceinexistingmodellingapproachesbasedsolelyonrealizednicheconditions.

Several lines of evidence that relate to conditions beyondthe realized niche provide a partial basis for examining potentialmismatches between species’ realized and fundamental niches.Mechanistic models characterize the bounds of the fundamentalnichebyexaminingspecies’physiological limits.Suchstudies,onawide variety of taxa, suggest that the fundamental niche is oftenmuch larger than the realizedniche andextends intowarmer andwetter climates (e.g., Araújo et al., 2013; Sunday, Bates, &Dulvy,2012).Hindcastingapproachesthatcomparecurrentandpastdis-tributionscanalsobeinformative.Forinstance,Ivory,Early,Sax,and

Russell(2016)foundthatfossildistributionaldataexposedsuitableclimatespacethatismaskedfromspecies’currentrangesbyhumanland use. Finally, considerations of the climatic conditions experi-encedinspecies’nativeandnon‐nativerangeshavea longhistoryintheliterature(e.g.,Boothetal.,1988;Booth&McMurtrie,1988;Grinnell,1922).However,multiple‐speciescomparisonsinthisveinhave only recently emerged (e.g., Gallagher et al., 2010). This ap-proachtypically involvesexaminingpopulationsoutsidethenativerangethatarenaturalized(i.e.,self‐sustaining,indicatingportionsofthefundamentalniche)orthosethatareadventive(i.e.,growingbutnotself‐sustaining,indicatingportionsofthetoleranceniche;sensu Saxetal.,2013).Anothersimilarandpromisingapproach involvesusingdatafromprovenancetrialswhereinindividualsfromvariouslocalitiesaregrownoutside thespecies’ range; inparticular,manytreespecieshavebeentestedinthiswaytoassesstheirsuitabilityforcommercialforestry(Booth,2017;Boothetal.,2015).

Despitethenascenceofthisliterature,twobroadpatternshavebeguntoemerge.First,thereisevidencethatspecieswithsmallna-tiverangesornarrowrealizednichesaremore likely toshowmis-matchesbetweentheirrealizednicheandeithertheirfundamentalortheirtoleranceniche.EarlyandSax(2014)foundstrongsupportforthispatternamongagroupof51Europeanplantsthathavenat-uralized in theUSA.Boscietal. (2016) foundasimilarpattern forplantsinNorthAmerica,suchthatspecieswithsmallnativerangesweremostlikelytohavelargemismatchesbetweennativeclimaticconditions and those inwhich species have become adventive. Incontrast,Petitpierreetal.(2012)foundthatmostspecieswithlargenative ranges showed only minor differences between native cli-maticconditionsandthoseinwhichthespecieshadbecomeestab-lished.Second,theliteratureexaminingclimateconditionsoccupiedbynativeandnon‐nativepopulationsindicatesthatunoccupiedpor-tionsofthefundamentalnichearelikelytobeinwarmerandwetterclimatesthanthenativerange,asexemplifiedbyastudyofamphib-ianandreptiledistributions(Li,Liu,Li,Petitpierre,&Guisan,2014).Theseresultsareconsistentwithmechanisticstudiesthatexaminephysiologicalandmetaboliclimits(e.g.,Araújoetal.,2013;Sundayetal.,2012).Moreworkisneeded,butifthesepatternswerewide-spread, a case could bemade that speciesmight fare better thanpreviouslyforecastintheirwarmingnativeranges.

Oneof the implicationsof climatic disequilibrium is that areaswithinaspecies’nativeregionorcontinentcanbeunoccupiedeventhoughtheyareclimaticallysuitable.Thiswasdemonstratedinclas-sicworkbySvenningandSkov(2004),whoshowedthatEuropeantreespeciesoccupyonlyaportionoftheclimaticallysuitableareaonthecontinent.Thisworkandthelargebodyofcontinuingworkon ‘range filling’has shownthatmost speciesdonot fill allof thesuitableareawithintheirnativeregionorcontinent(Bradley,Early,& Sorte, 2015; Dullinger et al., 2012; Nogués‐Bravo et al., 2014;Svenning & Skov, 2004). However, it is important to emphasizethatthisworkconsidersonlytherealizednichewhenmakingthesecomparisons (but seeBradleyet al., 2015). Thegrowing literatureonnativeandnon‐nativeclimatecomparisonssuggests thatexist-ingestimatesofrangefillingunderestimatethedifferencebetween

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realized conditions and the true climatically suitable area (Early&Sax,2014).Thismeansthatevenlessofthepotentiallysuitableareamight be occupied than previously thought. However, additionalwork isneededtoconstrainbetter thedegreetowhichrangefill-ingestimatesbasedsolelyonnativedistributionsmightcharacterizerangefillinginaccurately.

Variationinthemagnitudeofclimaticdisequilibriumamongspe-ciesalsohasimplicationsfortheevolutionofclimaticniches.Theideathatsimilaritybetweenspeciesshouldincreasewithrelatednesshasbeenlongestablished,andmorerecentworkhasidentified‘nichecon-servatism’asageneral tendency forclosely relatedspecies tohavemoresimilarfundamentalnichesorclimatictolerancesthanexpectedby chance (Holt &Gaines, 1992; Losos, 2008;Wiens et al., 2010).However,becausemostempiricalstudiesonnicheconservatismesti-mateonlytherealizedniche(e.g.,Anacker&Strauss,2014;Peterson,Soberón,&Sánchez‐Cordero,1999),thedegreetowhichpatternsofnicheconservatismextendto fundamentalnichespace remainsun-clear.Forexample,recentsimulationstudiesusingvirtualspecieshavedemonstrated that incompletely characterized fundamental nichestendtoinflateestimatedratesofnicheevolution(Saupeetal.,2017).Empiricalinvestigationoftheeffectofclimaticdisequilibriumonnicheconservatismrequiresagroupofspecieswithafinelyresolvedphy-logenyandabundantinformationaboutthefundamentalniche.

Although therearemany taxonomicgroups that couldbeusedtocomparenativeandnaturalizednicheconditions,thegenusPinus offersseveraladvantagesforsuchwork.First,therearedetailedandabundantdataaboutwherepinespeciesarenativeandintroduced.At least 25 species have become naturalized outside their nativeranges,oftenintheSouthernHemisphere,wheretheyhavebecomeinvasivepests(notably inSouthAfrica,AustraliaandNewZealand;Richardson&Higgins, 1998).Commercial forestry in the19th and20th centuries is largely responsible for these introductions, al-thoughtheearliestestimatesofhuman‐mediatedpineintroductionsrangeasfarbackas6,000BP(Barbéro,Loisel,Quézel,Richardson,&Romane,1998).Thereisconsequentlyalargeandvariedliteratureon thedriversofPinus introductionandnaturalization (Franzese&Raffaele, 2017; Nuñez & Medley, 2011; Richardson & Rejmánek,2004),andthegenushasevenbeenproposedasamodelsystemforstudyinginvasionecology(Richardson,2006).Second,thevariationinrangesizeamongpinespeciesspansseveralordersofmagnitude,fromPinus squamata,knownfromonlyasinglelocality,toPinus syl-vestris,withanativerangethatcoversmostofthePalaearctic(Farjon&Filer,2013).Moststudiesthusfarthatcomparenativeandnatu-ralizednicheshavefocusedonaparticularregionorregions,oftenusinganassemblagethatiswidelydispersedtaxonomically(Early&Sax,2014;Petitpierreetal.,2012).Incontrast,pinesallowstudyofasinglegenusataglobalscalewhilestillencompassingawiderangeofdistributionaltraits,nichetraitsandecologies.Third,asthemosteco-nomically important treegenus in theworld (Richardson&Rundel,1998), thehistorical native rangesofmostpine specieshavebeenexceptionally well characterized (Farjon & Filer, 2013). This allowsforthenativeclimaticconditionsofpinestobeestimatedwithmoreconfidencethanformanyothergroups.Finally,arecentlypublished

time‐calibratedphylogenyfortheentiregenus(Saladinetal.,2017)allowsforinvestigationofnicherelationshipsandconservatism.

Here,weusePinusasamodelsystemtoinvestigateclimaticdis-equilibriumandhowitchangesniche‐basedinferenceacrossacom-pletetaxon.Wedosobycomparingtheclimateoccupiedbynaturalizedpopulations of 25 pine specieswith that occupied by native popu-lationsof the same species.Weusenaturalized (i.e., self‐sustaining)populations,asopposedtothosethataremerelyadventive,inordertofocusonthoseconditionswhereitisclearthatanintroducedpop-ulationcanthrive.Weaskwhetherclimaticdisequilibriumisrandomacrossspeciesorstructuredbydistributionalornichecharacteristics.Wealsoexaminetheconsequencesofdisequilibriumforregionalandcontinentalrangefillingestimates,andtheimplicationsfornichecon-servatismofsisterspeciespairs.Finally,weexplorethe implicationsofthisworkforconservationofspeciesinthefaceofclimatechange.

2  | METHODS

2.1 | Occurrence data

Weacquireddataonthenativedistributionof109pinespeciesfromthe Conifer Database (Farjon, 2017). This carefully curated dataset isbuilt fromtaxonomicallyverifiedherbariumspecimens,withspecialcaretakentosampletheentiredistributionofeachspeciesandcontrolforspatialsamplingbias;fullcriteriaforinclusioninthedatabase are described by Farjon and Filer (2013).We processedthese data by removing occurrenceswith erroneous geographicalcoordinatesandremovedthreespeciesthathadeithertoofewoc-currencesor toorestrictedadistributiontobetractable fornichemodelling (P. squamata, Pinus amamiana and Pinus maximartinezii). To reduce the likelihood of erroneously including non‐native oc-currenceswithinthenativerangeofourfocalspecies,weremovedoccurrencesthatfelloutsidea100‐kmbufferaroundeachspecies’native range, as defined by expert rangemaps. Thesemapsweredownloaded from the United States Geological Survey digitizeddatabase of North American tree species (Fryer, 2018), digitizedfromCritchfieldandLittle(1966)orsuppliedbyNobis,Traiser,andRoth‐Nebelsick(2012).Althoughtheserangemapsarederivedfromsourcesofuncertainprecision,theyrepresentdecadesofworkbyresearchersattheU.S.ForestServicetofinelycharacterizethena-tiverangesofthesespecies,andthusarethemostcompletearea‐basedrangeestimatesforthisgroup.Intotal,ouranalysesinclude106species(SupportingInformationAppendixS1).

Dataonthenaturalizedoccurrencesofpineswerecollectedfromherbariumspecimensandaccountsintheliterature.Webeganher-bariumsearcheswiththespeciesandregionsidentifiedintheglobaldatabaseofinvasivetreesandshrubs(Rejmánek&Richardson,2013).Wesearched18herbariaandherbariumconsortiawithextensivedig-itizedpinecollectionsandrequestedphotographedspecimensfroman additional 35herbaria (Supporting InformationAppendix S2).Arecordwasincludedinourdatabaseonlyiftherewasclearevidencethatthespecimencamefromanaturalized(i.e.,self‐sustaining)popu-lationandifithadassociatedgeographicalcoordinates(seeexpanded

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descriptionsofourcriteriaandexamplesinSupportingInformationAppendix S2). Finally, we performed literature searches for publi-cations that contained references to naturalized pine populations(Supporting Information Appendix S3; Web of Science keywords:pinussp;naturaliz*;invas*;exotic;alien;adventive).AllrecordsweregeoreferencedandlocalitiesverifiedinGoogleEarth.Thecompletedatabasecontains597naturalizedoccurrencerecordsfor25speciesdistributedacross23countriesandfivecontinents.

2.2 | Niche modelling

Theselectionofappropriateclimaticvariables fornichemodellingorspeciesdistributionmodellingisofcrucialimportance(Petersonet al., 2011). Recent work by Petitpierre, Broennimann, Kueffer,Daehler, and Guisan (2017) suggests that climatic variables withknown ecological effects can predict plant distributionsmore ac-curately than variables selected using a model‐based approach.For this reason, we selected seven climate variables indicated tobe important or deterministic for pine growth and success of es-tablishment.OwingtothelonghistoryofPinuscultivation,thereisa large body of literature specific to pine silviculture onwhich todraw(e.g.,Boothetal.,1984;Poyntonetal.,1977).Ourfinalmodelsincludemeanannualtemperature(MAT),maximumtemperatureofthewarmestweek (MaxTemp),minimum temperatureof the cold-estweek(MinTemp),annualprecipitation(AnnPrecip),precipitationseasonality(PrecipSeas),non‐summerprecipitation(WinPrecip)andestimatedactualevapotranspiration(AET).Thefirstsixvariablesare30‐year averages (1961–1990) derived fromBioClim 1.2 variablesdownloaded from theCliMonddatabase in June2017 (Kriticosetal., 2012). Estimated actual evapotranspiration is supplied by theMODIS Global Evapotranspiration Project (MOD16; Mu, Zhao, &Running,2011).Allclimatedatawereresampledto10arc‐minreso-lution tomatchtheBioClimdata resolutionwith the lowestglobalerrorrates.Wealsorepeatedallanalyseswithasetofeightclimatevariables selectedby a principal components (PCs)‐based variableselectionmodel(sensuPetitpierreetal.,2017),althoughresultswerenotqualitativelydifferentandarenotpresentedhere.

Choosinganordinationtechniqueandmethodforcharacterizingnichespacethatsuitsthequestionisalsoofcrucialimportance.Giventhatwewereinterestedindirectinterspeciescomparisons,allnichemodelsneededtobebuiltinanequivalentspace(Broennimannetal.,2012).Giventheglobaldistributionofnativeandnaturalizedpines,webuiltallnichemodels in theglobalclimatespace.Following therecommendationsofBroennimannetal.(2012)andPetitpierreetal.(2017),wecalibratedaprincipalcomponentsanalysis (PCA)onthisglobalbackgroundandusedthefirsttwoPCaxes(containing84.39%ofthevariation)asacommonclimatespace.GiventhatmanypinesarenativetotheNorthernHemispherebutnaturalizedintheSouthernHemisphere,wealsoplottedtheclimateofeachhemispheretoassessthepotentialforsystematicdifferencesthatcouldinfluenceinterpre-tationofournichemodels(Qiao,Escobar,&Peterson,2017).

We initially built these niche models following the kernelsmoothing (“KS”) approachofBroennimannet al. (2012) but had

concernsaboutpotentialerrorresultingfromsamplingbiasesandunevensamplingintensitiesinthenativeandnaturalizeddistribu-tions.Inaddition,nichemodelsbuiltusingtheKSapproacharein-fluencedbyasmoothingparameter,h,estimatedasafunctionofthenumberandmeandispersionofoccurrencesinclimatespace.InspectionofKSnichemodelsshowednicheextensionintounoc-cupiedclimatespacecausedbysystematicdifferencesinthenum-beranddispersionofnativeandnaturalizedoccurrences.Forthesereasons,weusedminimumconvexpolygons(MCPs)tocharacter-izenichespace inall theanalysespresentedhere, for106nativedistributions and 25 combined native–naturalized distributions.Combiningnativeandnaturalizeddataallowedustobuildamin-imumestimateofthefundamentalnichespaceoutsidethenativerealizedniche(Broennimann&Guisan,2008;Early&Sax,2014).

2.3 | Analyses

Tocharacterizeclimaticdisequilibrium,wecalculatedtheamountofclimatespaceoccupiedbybothnativeandnaturalizedoccurrences(i.e., the extended niche, hereafterNE), in addition to the climatespaceoccupiedbyonlynativeoccurrences(i.e.,thenativerealizedniche,hereafterNR).Thedifferencebetweentheextendedandreal-izedniche,ΔN,canbeinterpretedastheamountofsuitableclimatespaceexposedbynaturalizedoccurrences:

WhereNR isasubsetofNE,whichisinturnasubsetofthefunda-mentalniche,NF:

Inordertocontrolfortheanisotropyandscaledependenceofclimatespace (Soberón&Peterson,2011),wecalculated the frac-tionofΔNthatisavailableonthenativecontinentofeachspecies,andthefractionofΔNthatoccurswithin300kmofeachspecies’nativerange(seeSupportingInformationFigureS4.1forconceptualdiagram).Allnichespaces(NE, NR and ΔN)areexpressedrelativetothesizeoftheglobalclimatespace(i.e.,NRof.10indicatesthatthespecies’nativerealizednicheencompasses10%oftheglobalclimatespace).Wealsocalculatedthevectorbetweenthegeometriccen-troidsofNR and NE.WeemphasizethatwedonotconsiderΔN or a largevectordifferenceevidenceofnicheevolutionorchangeperse(Petitpierreetal.,2012),butratherasevidenceoffundamentalnichespaceunoccupiedbythenativerealizedniche(Early&Sax,2014).

Capturingall possiblepredictorsof climaticdisequilibrium in asingleanalysiswouldbedifficultorimpossible.Giventhatwewereinterestedspecificallyinniche‐basedordistributionaltraits,wefo-cusedonthefollowingvariables:(a)NR,thesizeofthenativenicheMCPinPCAclimatespace;(b)nativerangesize,forwhichrangemapswereresampledtomatchclimatedataresolution,andrangesizewascalculatedas thenumberofoccupiedgridcells, log10‐transformedforanalyses;(c)nativenicheposition,thepositionofthenichecen-troidonbothPCaxes;(d)nativerangecentrelatitude,thelatitude

ΔN=NE−NR

NF⊇NE⊇NR

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ofthegeometriccentroidofthenativerange;and(e)nichemargin-ality,theclimatedistancefromthecentreofalloccurrencesacrossthe genus to the centre of each species’ native niche.We used arandomforestregressionapproachtorankpredictorvariableimpor-tancebasedonthemeandecreaseinmodelaccuracyacross10,000regression trees (Genuer, Poggi, & Tuleau‐malot, 2010). Randomforestsiterativelygrowbinaryregressiontreesusingbootstrappedobservationsamplesandarandomsubsetofpredictorvariablesateachnode(Breiman,2001).

To assess the consequenceof climatic disequilibriumon rangefillingestimates,wefollowedtheproceduresofSvenningandSkov(2004)andcalculatedrangefillingasthenumberofoccupiedgeo-graphical10′gridcellsdividedby thenumberofmodelledclimat-ically suitablegridcells.Theclimatically suitableareawasdefinedasall cells that fall inclimatespacewithin theMCPnicheofeachspecies.Werasterizeddetailednativerangemapstomatchthe10′resolutionofourclimatedataandusedthemtocharacterizetheoc-cupiedarea.Wecalculatedrangefillingforeachspeciesusingnativedataandcombinednative–naturalizeddata,bothonthecontinen-tal scale and restricted to theUnitedNations Food&AgricultureOrganization(FAO)ecofloristicregionsoccupiedbythespecies’na-tivedistribution(FAO,2000).Giventhatincorporationofnaturalizeddatacanonlyincreasethenumberofclimaticallysuitablegridcells,rangefillingestimatesmadeusingnaturalizeddatainadditiontona-tivedata are always equal toor lower than estimatesmadeusingonlynativedata.Wecalculatedthisdifferenceastheproportionalchangeinrangefillingwhennaturalizeddatawereincorporatedintothenichemodel.

Mostmethodsforcomparingtraitsacrossaphylogenydependon estimation of ancestral trait values at past nodes, as in phylo-genetic independent contrasts (Felsenstein, 1985). However, be-causeaspecies’climaticnicheisamanifestationoftheinteractionsbetween traits and the environment, reconstruction of ancestralnichesisdifficultandbeyondthescopeofthepresentstudy.Inaddi-tion,recentworkhasshownthatratesofnicheevolutiontendtobeoverestimatedwhenmodelsdependonincompletelycharacterizedfundamentalniches(Saupeetal.,2017).Forthisreason,wefocusedphylogenetic analyses on sister species pairs (Anacker & Strauss,2014; Peterson et al., 1999). Exploratory analyses were sensitivetodifferences intreetiptopology;becauseofthis,we limitedouranalysistoconsensussisterpairsacrossfourphylogeniespublishedbySaladinetal.(2017).Wefound21consensussisterspeciespairsinthegenus,eightofwhichhaveexoticdataforatleastoneofthespecies(SupportingInformationTableS4.1).Forthosepairs,wecal-culatednichesimilaritymetricsbothwithandwithoutincorporationofnaturalizedoccurrencedata.Therearenumeroustechniquesforassessingnichesimilarity (Broennimannetal.,2012;Warren,Glor,&Turelli,2008).Giventhatitremainsunclearwhichnichesimilaritymetricisbest,wecalculatedthefollowing:(a)nichecentredistance,thedistanceinPCclimatespacebetweenthegeometriccentroidsofeachniche;(b)nicheoverlap,theratioofsharedtototaloccupiedcli-matespace;and(c)nichenestedness,theproportionofthesmallerspecies’nichethatiscontainedwithinthelargerniche.Wecompared

similarityvaluesamongnon‐sisterpairs,sisterpairswithnativedataandsisterpairswithnaturalizeddatausingMann–WhitneyU‐teststoassessthehypothesisthattherealizednicheofonesisterpredictsthefundamentalnicheoftheother.Giventhatthespecifictiptopol-ogywithin several importantPinus subsections is poorly resolved(e.g.,Ponderosae,AustralesandStrobussub.Strobus;Parks,Cronn,& Liston, 2012; Saladin et al., 2017), we tested for phylogeneticstructureindisequilibriumamongthewell‐supportedgenussubsec-tionsthemselves(Parksetal.,2012;SupportingInformationFigureS4.2).WeusedanANOVAapproachtotestwhethervariationinΔN wasgreaterbetweensubsectionsthanwithinsubsections.Allanaly-seswereperformedinRv.3.2.4(RCoreTeam,2016).

3  | RESULTS

Amongthe25speciesthathavenaturalizedoutsidethenativerange,23 did so in climates outside the native realized niche (Figure 1;SupportingInformationAppendixS1).Amongthose23species,themedian ΔN was .018. Themaximum increase observed, for Pinus radiata,was.095(i.e.,theclimatespaceexposedbynaturalizedoc-currences encompasses almost 10% of the global climate space;Figure1;SupportingInformationTableS4.2).Thetwospeciesthatshowednonichedifference,Pinus resinosa and Pinus thunbergii, had onlytwonaturalizedoccurrenceseach.

Variation indisequilibriumwasnon‐randomacrossour25spe-cies, such that ΔN was strongly related to native realized nichesize,NR(Figure2).Generallyspeaking,ΔNtendedtobehigherandmore variable among species with small native niches, and loweramong thosewith large native niches. The proportion ofΔN thatwas available on species’ native continent was also significantlyand negatively related toNR (p < .01, R2=.46; Figure 2b). This re-lationshipwasweaker(butstillnegative)andnon‐significantwhentheavailableareawaspruned towithin300kmof species’nativeranges(p=.125;Figure2c).Whencomparedwithanullgeometricexpectationgeneratedbyrandomizingnaturalizedoccurrences,theobserved relationship betweenΔN and NR is significantly steeperthanthenullmodel(p=.003;fordetails,seeSupportingInformationFigureS4.3).Therandomizationprocedurealsodemonstratedthatspeciestendtonaturalizeclosertothenativenichethanexpectedbychance(p<<.001;SupportingInformationFigureS4.4).Theran-dom forest model examining the potential explanatory power ofrangeandnichecharacteristicsdidnotproducesignificantresults.

Variation inthedirectionofnicheextensionwasalsonon‐ran-dom(Figure3).Thelargestshiftsalloccurredinadirectionassoci-atedinPCclimatespacewithlowerprecipitationseasonality,higherannual precipitation and cooler temperatures (Figure 3c). This cli-mate directionwas not representative of climatic differences be-tweentheNorthernandSouthernHemispheres;southernclimateswere largely containedwithin the range of northern climates anddisplacedsuchthatthemedianclimateoftheSouthernHemispherewaswarmer andwetter than themedian climateof theNorthernHemisphere(SupportingInformationFigureS4.5).

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Theamountofrangefillingwefoundforeachspecieswasde-pendenton thescaleof thecalculation;median fillingamongallspeciesinnativecontinentsandecoregionswas16.75and30.62%,respectively.Addingnaturalizeddatauniformlyreducedrangefill-ingestimates,with amedianpercentagedecreaseof13.71%onnative continents and 2.89% in native ecoregions. Small‐nichedspeciesshowedsubstantialvariation intheirobservedchange inrangefilling(Figure4a),suchthattherelationshipbetweenNR and rangefillingchangemirroredtherelationshipbetweenNR and ΔN. Indeed, thesizeoftheeffectthatnaturalizeddatahadonrangefilling estimates was dependent on ΔN (p << .001, R2=.464).However,therewasalsoasignificantrelationshipbetweenrange

fillingchangeandnativerangesize(p << .001, R2=.55;Figure4b),suchthatthespeciesthatshowedthelargestrangefillingchangehadbothsmallnativenichesandsmallgeographical ranges.Therelationship betweenNR and range filling change also yielded asteeper relationship than expected when compared with a nullgeometric distribution (p<<.001; for details, see SupportingInformationFigureS4.6).

Thethreenichesimilaritymetricsweusedtoevaluatephyloge-netic niche relationships (niche centre distance, overlap and nest-edness) were all significantly more similar among sister speciespairs thanamongnon‐sisterpairs (Figure5;nichecentredistance,p=.006;overlap,p=.002;nestedness,p=.013).Amongtheeight

F I G U R E 1  Nichemodelsandgeographicaldistributionsfortwoexemplarspecies:Pinus mugo(a–c)andPinus radiata(d–f).(a,d)Occurrencesinclimaticnichespace[pointsandpolygonscorrespondtonative(blue)andexotic(red)occurrences,whereasthegreypolygonshowsthe‘genusniche’,thefurthestextentofanyspecies’occurrences].Nichemodelsarecalibratedonacommonprincipalcomponent‐transformedglobalclimatebackground.(b,e)Thesameoccurrencesinthenativerange(bluecircles)andnaturalizedrange(redtriangles).(c,f)Thenativedistribution(black),andgeographicalprojectionsofclimatenichespacebasedsolelyonnativeoccurrences(blue)andbasedonbothnativeandexoticoccurrences(red).ThedarkgreylineboundsthenativeFAOecofloristicregion(mainmap,panelc;inset,panelf)

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sisterspeciespairsforwhichat leastonememberhadnaturalizedoccurrences,wefoundnosignificantdifferencesinthemeanscal-culatedwithorwithoutnaturalizeddatafornichecentredistance,overlap and nestedness (Figure 5). Furthermore, individual sisterspecies pairs showed no consistent directional shift in similarity(Figure5).Noneofthesimilaritymetricswascorrelatedwiththeageofthesisterpairs,foreithernativeornative–naturalizeddatasets(allp>.40).Additionally,ourANOVAfoundnosignificantevidencethatΔN differed between genus subsections (p=.55), and genussubsectionsdidnotseparatebyΔN or NR (SupportingInformationFigureS4.7).

4  | DISCUSSION

Wefoundthatclimaticdisequilibriumamongpinesisnearlyubiqui-tousandisstructuredinahighlynon‐randommanner,suchthatspe-cieswithsmallnativerealizednichesaremorelikelytohaverangesin pronounced disequilibrium with their climatic tolerances thanlarger‐nichedspecies.Ourresultsareconsistentwithseveralrecent

studies that have found evidence of climatic disequilibrium usingnaturalizedplantdistributions(Boscietal.,2016;Early&Sax,2014;Gallagheretal.,2010).Ourresultsdifferfromsomepreviousstud-ies,however, in thatwefoundclimaticdisequilibriumtobenearlyubiquitousamongthespecieswestudied.Onlytwoofour25natu-ralizedspeciesshowednoevidenceofdisequilibrium,andthesetwospecieseachhadonly twonaturalizedoccurrences.Consequently,everyspecieswith threeormorenaturalizedoccurrencesshowedsomedegreeofdisequilibrium.

We suspect that our analysis focusing on pines provides abetter testof thepotential frequencyandmagnitudeofclimaticdisequilibriumthanmostothergroupsorstudiesforseveralrea-sons.First,mostothertaxaarenotaswidelyintroducedoutsidetheirnativerangeaspines(Richardson,2006).Second,asthemosteconomicallyimportanttreegenusglobally(Richardson&Rundel,1998), the native and naturalized ranges of pines are unusuallywell documented. Finally, existing studies of this topic have notconsidered all naturalized occurrences globally, but instead fo-cusedonthosewithinalimitedandpredefinedregion(e.g.,Early&Sax,2014;Petitpierreetal.,2012).Thisleadsustoconcludethat

F I G U R E 2  RelationshipsbetweenΔN(changeinnichesizeafterincorporatingnaturalizedoccurrences)andNR(nativenichesize).Foreachspecies,ΔNisdefinedasthedifferencebetweentheextendedniche(NE)andthenativerealizedniche(NR).(a)Therelationshipisfittedasanexponentialdecayfunction,weightedbythenumberofnaturalizedoccurrencesforeachspecies(a=.073;b=−9.222;p<.05).Symbolsizeisproportionaltothenumberofnaturalizedoccurrencesforeachspecies,rangingfromtwoto77;symbolcolourshowsthenumberofnativeoccurrences(fromblue,fewoccurrences,tored,manyoccurrences).(b)RelationshipbetweenNRandthefractionofΔNthatoccursoneachspecies’nativecontinent(p = .0002, R2=.4613).(c)RelationshipbetweenNRandthefractionofΔNthatoccurswithin300kmofeachspecies’nativerange.Thefittedlineisanexponentialdecayfunctionweightedbythenumberofnaturalizedoccurrences(a=.500,p=.0006;b=−5.814,p=.125)

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climaticdisequilibriummightbemuchmorecommonthanrecog-nizedbyrecentwork.

Ourfindingsalsoindicatethatthemagnitudeofthisdisequilib-riumcanbeestimatedbynativenichesize.This isconsistentwiththeresultsofEarlyandSax(2014),whoshowedthatnative–natu-ralizednicheexpansionwasnegativelycorrelatedwithnativenichebreadth among 51 European plant species that had naturalized intheUSA.Early andSax (2014) alsoprovidedcontext for the find-ingsofPetitpierreetal.(2012),whoshowedthatlarge‐ranged(andpresumably large‐niched)speciesshowedrelatively littlenicheex-pansionduringintercontinentalinvasions.Collectively,thisbodyofworksuggeststhatpredictionsofbiologicalinvasionsorspecies’re-sponsestoclimatechangethathingeonnativeclimaticconditionsmightperformpoorlyforsmall‐nichedspeciesevenwhileperform-ingwellforlarge‐nichedspecies.Forsmall‐nichedspecies,thelevelofclimaticdisequilibriumthatweobservedcanbeprofound.IntheextremecaseofP. radiata,thesizedifferencebetweenNR and ΔNap-proachesanorderofmagnitude,suggestingthatmodelprojectionsbasedsolelyonthenativerangeare likelytobewildlymisleading.Indeed,P. radiata is themostsuccessfulandwidespreadsoftwood

forestryspeciesintheworld(Booth&McMurtrie,1988;Richardson,2006),whilecuriouslyalsobeingatriskwithinitssmallnativerange.Althoughthemagnitudeoferrorisgenerallymuchlowerforlarge‐nichedspecies,similarprojectionscouldstillbemisleading.Amongthefivespecieswiththelargestnativeclimateniches(Pinus contorta, Pinus oocarpa, P. sylvestris, Pinus ponderosa and Pinus patula)westillfindameanΔNequivalentto3.55%oftheglobalclimatespace.

Giventhatouranalysescomparenichesofvastlydifferentsizeswithin a finite domain, we should expect to find a negative rela-tionshipbetweenNR and ΔN.Weexpectthisrelationshipbecauserandompointsinthisdomainaremorelikelytofalloutsideasmallnichethana largeniche.Thisnegativerelationship is indeedwhatweobserve;however,ourresultsdepartfromthisnullexpectationinthattherelationshipwefindbetweenNR and ΔNissignificantlysteeperthantherandomcase(SupportingInformationFigureS4.3).Additionally,whenweconsiderwhetherspeciesoccurincloseprox-imity to theclimatesencompassedbyΔN,we find that the small‐niched species that are most likely to be in pronounced climaticdisequilibriumarealsothosethataremostlikelytohaveunoccupiedsuitable climate space close to their native ranges. This provides

F I G U R E 3   (a)Relationshipbetweenthedirectionandmagnitudeoftheshiftbetweennativeandnative–naturalizednichecentroidsshowsthemagnitudeoftheshift[inunitsofprincipalcomponent(PC)distance]relatedtotheangulardirectionoftheshift(c).SizeofpointsisproportionaltoΔN.ColourindicatesnumberofnativeoccurrencepointsandrelatesspeciestoFigure2.(b)Thesameshiftsinclimatespacerelativetothegenusniche.(c)Loadingsofclimatevariablesontheprincipalcomponentsanalysisbackground.Variablesincludedaremeanannualtemperature(MAT),maximumtemperatureofthewarmestweek(MaxTemp),minimumtemperatureofthecoldestweek(MinTemp),annualprecipitation(AnnPrecip),precipitationseasonality(PrecipSeas),non‐summerprecipitation(WinPrecip)andestimatedactualevapotranspiration(AET)

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strongevidencetosuggestthatsmall‐nichedspeciesarelimitedbynon‐climaticfactorsintheirnativeranges.Indeed,giventheubiquityofthedisequilibriumthatweobserved,itraisesthepossibilitythatfew,ifany,speciesarelimitedentirelybyclimate.

Ourresultsalsoprovideinsightintowhichedgesofapinespe-cies’realizednicheareleastlikelytobedeterminedbyclimatealone.Wefoundthedirectionofnicheextensionstobeconservedacrossspecies toward cooler, wetter and less seasonal climates. Giventhat 19 of the 25 naturalized pine specieswe focused on are na-tive in theNorthernHemisphere and naturalized in the SouthernHemisphere, it is worth consideringwhether general hemisphericdifferences in climate drove this result. This seems unlikely, how-ever, because the global climate space we constructed does notseparate by hemisphere, and the landmasses typically invaded bypinespecies (e.g.,NewZealand,Australia)containconditionsbothwarmer anddrier thanmany species’ native ranges.Niche expan-sionintocoolerandwetterconditionsindicatesthattheseportionsofthefundamentalnicheareoftenunoccupiedinthenativerange,especiallyforsmall‐nichedspecies.Thisisindirectcontrasttostud-iesthatusemechanisticphysiologicalmodelstoexplorespecies’cli-matictolerances,andwhichgenerallyfindunoccupiednichespacetobewarmerandwetterthanthenativerange(Araújoetal.,2013;

Sundayetal.,2012).ThisisalsoincontrasttothefindingsofBoothetal.(1988),whouseddatafromforestrytrialstoshowthateuca-lyptspeciesgenerallythriveoutsideofthenativerangeinwarmeranddrierclimates(althoughonespeciesintheiranalysis,Eucalyptus citriodora,was successfully grown in cooler climates, and another,Eucalyptus cladocalyx, was successfully grown in wetter climates).Also, although forestry trials are a valuable source of informationabout the climates inwhich tree species cangrow in theabsenceof certain biotic interactions, they generally do not provide infor-mationaboutthereproductivesuccessofspecies(Booth,2017).Incontrast, ourworkexplicitly examines conditionswhere a speciescannotonlygrowandsurvive,butalsoreproducesufficientlywellto sustainapopulation in thepresenceofbothbiotic interactionsandothernon‐climaticfactors.Althoughmanypinespeciesarelonglived, and individualsmay be able to survivewithout reproducingaftersignificantclimaticshifts,reproductioniscriticaltolong‐termpopulationpersistence (Booth,2017;Saxetal.,2013). Indeed,ex-aminingreproductivepopulationsisacrucialaspectofourworkthatallowsustocharacterizeportionsof thefundamentalnicheconfi-dently.Giventhe limitednumberofstudiesthathave investigatedthisissueandthedisparateapproachesandtaxaused,itisdifficulttoknowwhetherageneraltrendwillemergeregardingpatternsof

F I G U R E 4   Relationshipoftheproportionalchangeinrangefilling(RF)toNR,nativerangesizeandΔN.‘Proportionalchangeinrangefilling’iscalculatedastheproportionalchangebetweenrangefillingestimatesusingonlynativerangedataandthoseincorporatingnaturalizeddata.(a)RelationshipbetweenproportionalchangeinrangefillingandNR,fittedasanegativeexponentialfunctionweightedbythenumberofnaturalizedoccurrencesperspecies(a=−1.195;b=−35.559;p<<.001).Symbolsizeisproportionaltothenumberofnaturalizedoccurrencesforeachspecies,rangingfromtwoto77;symbolcolourshowsthenumberofnativeoccurrences(fromblue,fewoccurrences,tored,manyoccurrences).(b)Relationshipbetweenproportionalchangeinrangefillingandnativerangesize(p << .001, R2=.547).(c)RelationshipbetweenproportionalchangeinrangefillingandΔN(p << .001, R2=.464)

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unoccupiednichespace.Itispossiblethatnon‐climaticfactors(e.g.,bioticinteractionsordispersallimitations)constrainspecies’nichesinidiosyncraticways.It isalsopossiblethatdifferentdatasourcesandanalyticalapproacheswilluncoverdifferentportionsofthefun-damentalniche.

Rangefillingestimateshavehadastrongandsoberingimpactonthenichemodellingfieldoverthepast15years.Byshowinghowin-frequentlyspeciesfillalloftheclimaticallysuitablespacewithintheirnative regionor continent (Bradley et al., 2015; Svenning&Skov,2004),thesestudiesbringintoquestiontheappliedutilityofpurelycorrelativespeciesdistributionmodels.Here,weshowthatthede-greeofrangefilling isevenlessextensivethanpreviouslythoughtformanyspecies,particularlythosewithsmallnativeniches.Indeed,naturalizedclimateconditionsshowthatnativerangedatacanover-estimaterangefillingbyupto89.78%onthecontinentalscale(e.g.,P. radiata) and 56.11% on the ecoregional scale (e.g.,Pinus clausa;

Supporting Information Table S4.2). In contrast to these extremeexamples,insomecaseswefoundthatΔNwasnotassociatedwithasubstantialchangeinrangefillingestimates.Thisoccurredwhennovelclimatespaceoccupiedinthenaturalizedrangedidnotoccuronthenativecontinentorinthenativeecoregion(e.g.,Pinus taeda is naturalized in southern Brazil, Argentina and eastern Australiabut experiences conditions there that are not found on its nativecontinentofNorthAmerica;seeSupportingInformationAppendixS1andTableS4.2).Suchfindingsweremorelikelyforlarge‐nichedspecies,whichtendedtohaveasmallerfractionoftheclimatescon-tained inΔN availablewithin the native continent and ecoregion.Consequently,althoughNR and ΔNareimportantpredictorsoftheaccuracyofrangefillingestimates,theyarenotinthemselvessuffi-cienttodescribetheserelationshipsfully.Thesizeofaspecies’na-tiverangeprovidesadditionalinformationinthisrespect,suchthatsmall‐nichedspeciesthatalsohavesmallnativerangesarethoseforwhichrangefillingestimatesareleastaccurate.

Phylogenetic niche conservatism, the tendency for closely re-latedspeciestohavemoresimilarnichesthanexpectedgiventheirrelatedness,couldbeleveragedtoinvestigatethestructureoffun-damental niche space and climatic disequilibrium further (Losos,2008;Wiensetal.,2010).There issomeevidencetosuggestthatrealizednichesimilarityunderestimatesfundamentalnichesimilar-ity(Araújoetal.,2013;Sundayetal.,2012).Ourfindings,however,werenotconsistentwiththissupposition,becausewefoundnoevi-dencetosupporttheconjecturethatconsideringfundamentalnichespaceincreasesthesimilarityofsisterspecies.Ofcourse,becausewehadonlyeightsisterpairswithatleastonenaturalizedspecies,our statistical power here is low. It is possible that another taxo-nomicgroup,ifanalysedinthesameway,wouldshowdifferentre-sults.Pinusisanunusuallyoldgenus,withsplitsamongsisterspeciesthatrangeinagefrom1.4(Pinus hartwegii and Pinus pseudostrobus) to16.8Myr(Pinus halepensis and Pinus brutia),amongtheconsensuspairsweassessed(Saladinetal.,2017).Itispossiblethatayoungergenuswithmorerecentsplitswouldbemoresensitivetotheinclu-sionofnaturalizeddata.Ideally,futureworkcouldinvestigatetheserelationshipsusingdifferenttaxawithbothalargernumberofsisterpairsandyoungerdivergenceages.

Ourapproachofusingnaturalizedoccurrencestoidentifysuit-ableclimatespaceoutsidethenativerealizednichenecessarilypro-ducesaminimumestimateofthefundamentalniche.Thisisprimarilyaresultofselectiveandunequalattemptsatintroduction;nospe-cieshasbeenintroducedwithequalpressureinallpossibleclimates.This is compoundedby incomplete samplingand specimencollec-tion across species’ exotic ranges. Additionally, non‐climatic fac-torsthatconstrainspecies’realizednichesinthenativeregion(e.g.,competition,soil,facilitation)mayalsobelimitingintheintroducedregion,toanunknowndegree.Althoughtheseareunavoidablelim-itationsof our approach, they alsomean that ourmethodology isespeciallyconservativewithrespecttonichedifferences.Giventhatweareworkingwithminimumestimates,weareunlikelytooveresti-matethefrequency,magnitudeoreffectsofclimaticdisequilibrium.This is in contrast tootherapproaches thatestimate fundamental

F I G U R E 5  Nichesimilarityofsisterspeciescomparisons.Inorderfromtoptobottom,greybarsarepairwisecomparisonsofallnon‐sisterspecies(106species;5,493pairs),greenbarsaresisterspeciespairsusingnativedataonly(21pairs),bluebarsarealsocalculatedsolelywithnativedatabutrepresentthosepairsthathaveatleastonemembernaturalized(eightpairs),andredbarsaresisterspeciescomparisonsthatincorporatenaturalizeddata(eightpairs).Arrowsindicatewhereasisterpaircomparisonmovedwhennaturalizeddatawereincorporated.(a)Centredistance,thedistanceinclimatespacebetweentwonichecentroids.(b)Nicheoverlap,theratioofsharedtototaloccupiedclimatespace.(c)Nichenestedness,theproportionofthesmallernichethatiscontainedwithinthelargerniche

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nichespacefrommeasurementsofphysiologicallimitsalongasin-gle niche axis,whichmay overestimate the fundamental niche byfailingtoaccountforcombinationsofextremeconditions(Maguire,1973).Additionally,itispossiblethatthecoarseresolutionofourcli-matedatamasksfine‐scalevariationandmisrepresentssomeoftheclimatespaceoccupiedbypopulations in topoclimaticallycomplexareas.However, this effect is unlikely tobe systematic enough toproducethepatternsthatweobservedinthemagnitude,frequencyanddirectionalityofclimaticdisequilibrium.Afinalfactorthatcouldinfluencetheinterpretationofourresultsisthepotentialforrapidadaptiveevolutiontonovelclimateconditionsinintroducedpopu-lations,suchthatthenativenicheandthenaturalizednicherepre-senttwodifferentsetsofclimatictolerances.However,becausethePinaceaeareknownforpronouncedevolutionaryconservatismandslowmutationrates(Prageretal.,1976),suchconcernsseemlessrel-evantforthisgroup.Additionally,becausepineshavelonggenera-tiontimesandmostintercontinentalintroductionshavetakenplacewithinthepast200years(Richardson&Higgins,1998),itseemsun-likely thatsuchrapidevolutionhasoccurredatsufficient levels toimpactourresultsstrongly.Nevertheless,wecannotcompletelyruleoutthispossibility,andsomefractionoftheobservednichediffer-encecouldbeattributabletoevolutionarychanges(Saxetal.,2007).

Our results lead us to conclude that analyses focused solelyon conditions experienced in a species’ native range and regionmaybemisleading,especially forconservationapplications.Thisisparticularlytrueforspecieswithsmallnativeclimaticnichesandsmall native ranges,whichwealsoexpect tobeatelevated riskfromclimatechangeandhabitat loss.Forthesespecies, refiningourunderstandingofclimaticdisequilibriumanditsconsequencesfor range filling estimates and niche conservatism is especiallyimportant.Our findingssuggest thatstandardnicheandspeciesdistributionmodellingtechniquesthatdonotaccountforclimaticdisequilibrium are inadequate for studying small‐niched species.Ourfindingsalsosuggestthatmodellingapplicationsthatrequirefine‐levelclimatictoleranceswillmisrepresentevenlarge‐nichedspecieswhenconsideringnativeconditionsalone,becausethesespeciesalsoshowsomedegreeofclimatedisequilibrium.Withre-specttopines,ourresultssuggestacapacitytothrive incooler,wetter and less seasonal conditions than those known from therealized distribution alone. Unfortunately, this particular bit offundamentalnichespacewillnotprotect thesespecies from fu-ture climatic changes, which are generally expected to producewarmer andmore seasonal conditions. This implies that speciescurrentlyrestrictedtoenvironmentswheredispersalcannotoccur(e.g.,alpineorislandendemicspecies)areatriskofextinction.Thisconclusion isconsistentwithSaxetal. (2013),whosuggest thattherelativesizeandplacementofnichecomponentsiscriticalforinformingcurrentandfutureconservationaction.Ultimately,ourfindingsemphasizethattherearelargegapsinourunderstandingofwhere,whenandhowspeciesoccupytheirfundamentalnichespace.Tohelpfillthisgap,wehopethatfutureworkcapitalizesonthedatacontainedinglobalherbariumcollectionsandtheinsightsaffordedbyspeciesintroductionsandglobalforestrytrials;doing

soshouldleadtoabetterunderstandingofthesephenomenaandimproveourabilitytoassessconservationrisksaccurately.

ACKNOWLEDG MENTS

Many thanks are owed to the herbaria listed in SupportingInformationAppendixS2thatsuppliedspecimensanddistributiondata,andespeciallytoA.FarjonforcompilingandmaintainingtheConiferDatabase;toR.Early,E.HollenbeckandL.Nunesforhelp-fuldiscussionandguidance;andtoC.Peabodyfordatacollection.Themanuscript also benefitted from insightful comments from J.Soberónandtwoanonymousreferees.

DATA ACCE SSIBILIT Y

Thedatainthispaperwerecollectedfromfreelyavailablesources.OccurrenceandclimatedatausedintheanalysesareavailableinaDataDryadrepository:https://doi.org/10.5061/dryad.1hr1n52

ORCID

Daniel L. Perret http://orcid.org/0000‐0001‐6372‐9243

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SUPPORTING INFORMATION

Additional supporting information may be found online in theSupportingInformationsectionattheendofthearticle.

How to cite this article:PerretDL,LeslieAB,SaxDF.Naturalizeddistributionsshowthatclimaticdisequilibriumisstructuredbynichesizeinpines(Pinus L.). Global Ecol Biogeogr. 2018;00:1–13. https://doi.org/10.1111/geb.12862

BIOSKETCHESDaniel Perret’swork ismotivated by the challenge of applyingbiogeographical insight toconservationproblems.His researchfocusesondetanglingpatternsamongclimaticnichesandgeo-graphicalrangesoftreespeciesglobally.anDrew leslieisbroadlyinterestedintheevolutionofplantrepro-ductivemorphology,usingconifersasaprimarystudygroup.Hiswork integrates phylogenetic analyses, functional morphologyanddatafromthefossilrecordinordertounderstandthedriversofmorphologicaldiversificationovermillion‐yeartime‐scales.Dov sax isabiogeographer interestedbroadly inconservation,withaspecialemphasisonunderstandingandpreventingspeciesextinctions.Mostofhisworkismotivatedbyspeciesinvasionsorclimatechange.