SystematicBotany (1996), 21(3): pp. 365-379 ? Copyright1997 by theAmerican Society of Plant Taxonomists Molecular PhylogeneticAnalysis of the Hawaiian Endemics Schiedea and Alsinidendron(Caryophyllaceae)
PAMELA S. SOLTIS, DOUGLAS E. SOLTIS Departmentof Botany, Washington State University, Pullman, Washington 99164-4238
STEPHEN G. WELLER, ANN K. SAKAI Departmentof Ecology and EvolutionaryBiology, University of California, Irvine, California 92717
WARRENL. WAGNER Departmentof Botany, Smithsonian Institution, Washington, D.C. 20560
CommunicatingEditor: Kent E. Holsinger
ABSTRACT. Schiedeaand Alsinidendron(Caryophyllaceae), which representthe fifthor sixth largest endemicradiation of species in the angiospermflora of the Hawaiian Islands,exhibit striking diversity in morphology,breeding system, and habitat.To gain a historicalperspective on thisdiversity, we conducteda phylogeneticanalysis using restrictionsite variationin chloroplastDNA and nuclearribosomal DNA. In addition,we compared,and ultimatelycombined, the molecular data witha recentlypublished morphologi- cal data set. Withinthe Schiedea-Alsinidendronlineage, DNA variationis limited,and relationshipsare generallypoorly resolved. These resultsraise the possibilitythat, following the initialcolonization of the Hawaiianarchipelago and theearly diversification of thecomplex, much of the complex radiated rapidly and relativelyrecently. Phylogenetic analyses of DNA data revealed threeclades withinthe complex (the S. membranacea,S. nuttallii,and S. adamantisclades), in agreementwith resultsof a morphologically-based analysis.Molecular data do not,however, support the S. globosaclade, a weakly-supportedclade based on morphology.A combinedanalysis of morphological and moleculardata providedboth greater resolution and strongerinternal support than eitherdata set did individually.The molecularand combinedtopologies suggestnearly identical patterns of the evolutionof sexual dimorphism,habitat shifts, and biogeography withinthe complex.However, the greaterresolution in treesderived from the combinedanalysis suggests simplerpatterns of breeding-system evolution and habitatshifts. Sexual dimorphismmay have evolvedtwice in thecomplex, with a singlereversal to hermaphroditismin one species,or perhapsonly once, with three reversalsto hermaphroditism.Although the habitatoccupied by the ancestorof the complex remains uncertain,it appearsthat a singleshift to dryhabitats more or less accompaniedthe evolution of dimorphic breedingsystems, followed by a singleshift back to a mesicenvironment in one species.Alternatively, two parallelshifts to dryhabitats may have occurred.Molecular data areconsistent with an originon Kaua'i ofthe S. membranacea,S. adamantis,and S. nuttalliiclades, as suggestedby previous morphologicalanalyses. However,both the molecular and combinedtrees suggest it is equallylikely that the complex originated on O'ahu.
Schiedea and Alsinidendron(Caryophyllaceae: generais amongthe most striking in Caryophylla- Alsinoideae), genera endemic to the Hawaiian ceae; the species vary fromlarge vines of wet Islands, exhibit a wide diversityof breeding foreststo compactshrubs, subshrubs, and peren- systemsand morphologyand occur in a broad nial herbsof dry, exposed sites. arrayof habitats(Wagner et al. 1995;Weller et al. Schiedeaand Alsinidendrontherefore pose a series 1995). Schiedeaand Alsinidendroncomprise 25 and of intriguingevolutionary questions (Wagner et al. fourspecies, respectively, and formthe fifth or sixth 1995). One of the most noteworthyphylogenetic largestendemic radiation of species in the Hawai- problemsis the possibilitythat Schiedeamay be ian angiospermflora (Wagner et al. 1995).Despite paraphyletic,with Alsinidendronderived from theirdiversity in morphology,breeding system, withinSchiedea (Wagner et al. 1995). Schiedeaand and habitat,they constitute a monophyleticgroup Alsinidendronalso representuseful models for based on a suiteof unusual morphologicalcharac- addressingpatterns of morphologicaland ecologi- ters(Weller et al. 1990,1995; Wagneret al. 1995). cal diversification.For example,breeding-system The variationin bothhabit and habitatin thesetwo diversityis correlatedwith habitat in thesegenera.
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Ten species of Schiedeahave dioecious, subdioe- nated and cultured in the greenhousesat the cious,or gynodioeciousbreeding systems (Table 1). Universityof California,Irvine. For a few taxa, All species having separate sexes occur in dry leaves were collected in the field and mailed habitats,whereas hermaphroditic species are largely directlyto the laboratory (Washington State Univer- restrictedto mesicareas (Welleret al. 1990,1995). In sity) for isolation of DNA. We isolated high- addition, most species with separate sexes are molecular-weighttotal DNA's usingseveral proce- wind-pollinatedwhereas those species that are dures. For some taxa, modifications(Soltis et al. hermaphroditicare eitherinsect-pollinated or au- 1991)of the mini-prep protocol of Doyle and Doyle togamous(Weller and Sakai 1990).Weller and Sakai (1987) workedsuccessfully. However, these modi- (1990)therefore suggested that a scarcityof pollina- fiedmini-prep methods for DNA isolationdid not torsin dry,windy environments may have resulted provide suitable quantities of high-molecular- in increasedselfing rates, inbreeding depression, weight DNA for many of the taxa investigated. and thespread of male-sterile forms. Most recently, Therefore,for most species a large-scaleDNA Welleret al. (1995)examined patterns of breeding- isolationprocedure (Rieseberg et al. 1988;Soltis et system evolution in Schiedeaand Alsinidendronal. 1991) requiring10-20 grams (freshweight) of througha phylogeneticanalysis of morphological leafmaterial was used. characters;however, relationships based on morpho- DNA's were digested with the following28 logical characterswere generally weakly sup- endonucleases using the specificationsof the ported,and patternsof breeding-system evolution suppliers:AccI, ApaI, AvaI, AvaIl, BanI, BanlI, BglI, werenot entirely resolved. BglII,BstEII, BstNI, BstXI, ClaI, CfoI,EcoRI, EcoRV, To resolvefurther the phylogenetic relationships HaeII, HindIII,HpaII, NciI, PvuII, PstI, SmnI,SspI, in Schiedea and Alsinidendronand to explore Sacl, SaclI, Sall, XbaI, and XhoI. DNA fragments patterns of diversificationin this lineage, we were separated in 1.0% agarose gels, denatured, employedanalyses of restrictionsite variationin and transferredto nylonmembranes (ZETABIND, both the chloroplastgenome (cpDNA) and the Cuno LaboratoryProducts, Meriden, Connecticut) nuclear18S-26S ribosomal RNA genes (rDNA). We followingthe general methods of Palmer (1986). also comparedthe DNA-based topologieswith the HeterologouscpDNA probesfrom lettuce (Jansen morphologically-basedtrees of Welleret al. (1995). and Palmer1987) and petunia(used in place ofthe Furthermore,we combined the molecular and 22-kbinversion present in the chloroplastgenome morphologicaldata sets and conductedadditional of lettuce)were labeled using theRandom Primed phylogeneticanalyses. Our specificobjectives were: DNA LabelingKit (U. S. BiochemicalCorporation, 1) to elucidate phylogeneticrelationships in the Cleveland,Ohio) and hybridizedto themembrane- Schiedea-Alsinidendronlineage; and 2) to testrecent bound DNA fragments.cpDNA probeswere kindly hypothesesof breeding-systemevolution, habitat provided by J. D. Palmer and R. K. Jansen.To diversification,and biogeography(Wagner et al. analyze rDNA variation,filters were probed with 1995;Weller et al. 1995). pGMr-1,a plasmid containinga single 18S-26S rDNA repeatfrom Glycine max L., kindlyprovided MATERIALS AND METHODS by E. A. Zimmer.Restriction sites were scored as present(1) or absent(0). Missingdata were scored Plant Samples. Included in the DNA analyses as question marks;2.5% of the data matrixcells were threeof thefour species ofAlsinidendron and werescored as missing. 17 ofthe 23 extantspecies of Schiedea (Table 1). Two species, S. amplexicaulisH. Mann and S. implexa PhylogeneticAnalysis of Molecular Data Set. (Hillebr.)Sherff, are consideredextinct. Of the six Restrictionsite data were analyzed with various extantspecies of Schiedeanot included,five were optionsof PAUP 3.1.1 (Swofford1991). To evaluate eitherunknown, not recognizedtaxonomically, or the nonrandomstructure of boththe cpDNA data thoughtto be extinctat thetime of DNA analyses. set and the combinedcpDNA and rDNA data set, Moehringialateriflora, also ofsubfamily Alsinoideae, the skewnesstest (Hillis 1991; Huelsenbeck1991; and Silenestruthioloides of subfamilySilenoideae Hillis and Huelsenbeck1992) was performed.For wereused as outgroups. the skewness analyses, the RANDOM TREES cpDNA and rDNA RestrictionSite Analysis. featureof PAUP was used to generate 10,000 Formost species investigated, seeds werecollected randomtrees and to calculatethe gi statisticbased fromplants in the fieldand subsequentlygermi- on the distributionof the lengthsof these trees.
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TABLE1. Breedingsystems of species analyzed and islands where samples were collected.Except where noted, collectionnumbers are thoseof Weller and Sakai,and vouchersare at US.
Species Sample Island Breedingsystem
Alsinidendronlychnoides (Hillebr.) Sherff 867 Kaua'i Hermaphroditic A. obovatumSherff 868 O'ahu Hermaphroditic A. trinerveH. Mann Perlman5448 (BISH) O'ahu Hermaphroditic Schiedeaadamantis St. John 847 O'ahu Gynodioecious S. apokremnosSt. John 865 Kaua'i Gynodioecious S. diffusaA. Gray 848 Maui Hermaphroditic S. globosaH. Mann 844 O'ahu Subdioecious S. globosa 850 Maui Subdioecious S. globosa 852 Maui Subdioecious S. haleakalensisDegener & Sherff 851 Maui Dioecious S. hookeriA. Gray 794 O'ahu Hermaphroditic S. kaalaeWawra 881 O'ahu Hermaphroditic S. kealiaeCaum & Hosaka 791 O'ahu Subdioecious S. kealiae 862 O'ahu Subdioecious S. ligustrinaCham. & Schlechtend. 873 O'ahu Dioecious S. lydgateiHillebr. 870 Moloka'i Hermaphroditic S. manniiSt. John 793 O'ahu Subdioecious S. membranaceaSt.John 864 Kaua'i Hermaphroditic S. menziesiiHook. 849 Maui Hermaphroditic S. nuttalliiHook. 861 O'ahu Hermaphroditic S. pubescensHillebr. 796 O'ahu Hermaphroditic S. salicariaHillebr. 842 Maui Gynodioecious S. spergulinaA. Gray 863 Kaua'i Dioecious Moehringialateriflora (L.) Fenzl. 886 Japan Hermaphroditic Silenestruthioloides A. Gray 882 (no voucher) Maui Hermaphroditic
Phylogeneticanalyses were conducted with (Welleret al. 1995) and reanalyzedthis abridged MULPARS, TBR branch-swapping,and "un- data set.All charactersused by Welleret al. (1995) weighted"character-state changes (in whichgains were includedin thisreanalysis; as in Welleret al. and losses are weighted equally). To test for (1995),breeding-system characters were excluded multipleislands of most parsimonious trees (Mad- fromthe analysis because of the likely parallel dison 1991), 100 replicate tree searches with evolutionof sexual dimorphism within the Schiedea- RANDOM taxon addition were conducted. To Alsinidendroncomplex. The morphologicaldata obtain estimatesof reliabilityfor monophyletic wereanalyzed with PAUP 3.1.1as describedabove. groups,bootstrap analysis (Felsenstein 1985) using PhylogeneticAnalysis of Combined Morphologi- 100 replicatesand decay analysis (Bremer1988) cal and Molecular Data Set. We also combined usingthe converse constraint method (Baum et al. themolecular (cpDNA and rDNA restrictionsites) 1994) were conducted. We first analyzed the and abridged morphologicaldata sets and con- cpDNA restrictionsite data set,then repeated the ducted phylogeneticanalyses as above, except analysis with the rDNA restrictionsite changes using 1,000bootstrap replicates and saving up to added. 1,000trees per replicate. Reanalysis of Morphological Data Set. The cladisticanalysis of morphologicaldata (Welleret RESULTS al. 1995)involved additional taxa not analyzedfor DNA variationbecause herbariumspecimens of Phylogenetic Analysis of Molecular Data. rareor extinct taxa could be studiedfor morphologi- Forty-sixcpDNA restrictionsite mutationswere cal characters.Adequate amounts of leaf material of detected,31 of whichwere sharedby two or more mostof these rare and/or extinct taxa could notbe species (includingthe outgroups) and werepoten- obtainedfor restriction site analysis.We therefore tiallyparsimony-informative (Table 2, Appendix 1). removedthose taxa forwhich molecular data were However,13 ofthese 31 informativerestriction site not available from the morphologicaldata set mutationsdifferentiate the outgroupspecies from
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TABLE2. Restrictionsite mutations detected in theSchiedea-Alsinidendron complex. The restrictionenzymes for which mutationswere observed and thelocations of the mutations in thechloroplast genome or nuclear ribosomal DNA, along withthe probes used to detectthem, are provided.Regions of thechloroplast genome are designatedas: LSC = Large Single-CopyRegion; SSC = SmallSingle-Copy Region; IR = InvertedRepeat. cpDNA probesare fromLactuca and are labelledLac withthe fragment size (Jansenand Palmer1987) or Petunia(labelled Pet); all cpDNA probeswere provided by B. Jansenand J.Palmer. Mutations 47-49 occur in thenuclear rDNA and are so designated.The rDNA probe is labelled GlycinerDNA and was providedby L. Zimmer.Fragment sizes foreach restriction site are given, with the larger fragment listedfirst (site absent) and thesmaller fragments (site present) following. Character states (presence or absence)for these restrictionsites are givenfor all taxain theAppendix.
Character Restrictionenzyme Location of mutation;probe Restrictionsite
1 ApaI SSC; Lac 18.8 7.9-6.7+ 1.2 2 BanIl SSC; Lac 18.8 10.0-5.5+ 4.5 3 AvaIl SSC; Lac 18.8 5.1-2.8+ 2.3 4 BglII SSC; Lac 18.8 11-3.5+ 7.0 5 BstEII SSC; Lac 18.8 6.6-3.3+ 3.3 6 BstNI SSC; Lac 18.8 3.2-2.4+ 0.8 7 BstXI SSC; Lac 18.8 11.5-6.2+ 5.3 8 EcoRI SSC; Lac 18.8 2.7-2.2+ 0.5 9 EcoRI SSC; Lac 18.8 4.4-2.7+ 1.7 10 HaeII SSC; Lac 18.8 4.4-2.7+ 1.7 11 PvuII SSC; Lac 18.8 4.6-3.5 + 1.1 12 XbaI SSC; Lac 18.8 8.2-2.7+ 5.5 13 BanI IR; Lac 12.3,9.9, 3.5, 1.8 1.3-0.8+ 0.5 14 BanI IR; Lac 12.3,9.9, 3.5, 1.8 13.6-6.8+ 6.8 15 BanI IR; Lac 12.3,9.9, 3.5, 1.8 7.3-5.2+ 2.1 16 BanII IR; Lac 12.3,9.9, 3.5, 1.8 12.0-11.5+ 0.5 17 BanII IR; Lac 12.3,9.9, 3.5, 1.8 1.5-1.0+ 0.5 18 CfoI IR; Lac 12.3,9.9, 3.5, 1.8 10.0-9.0+ 1.0 19 AvaIl IR; Lac 12.3,9.9, 3.5, 1.8 5.0-4.0+ 1.0 20 Bglll IR; Lac 12.3,9.9, 3.5, 1.8 6.0-4.0+ 2.0 21 BstXI IR; Lac 12.3,9.9, 3.5, 1.8 15.0-10.0+ 5.0 22 BstNI IR; Lac 12.3,9.9, 3.5, 1.8 5.0-3.5+ 1.5 23 XmnI IR; Lac 12.3,9.9, 3.5, 1.8 12.0-11.0+ 1.0 24 XmnI LSC; Pet9.0, 9.2, 15.3 6.0-5.0+ 1.0 25 HindIII LSC; Pet9.0, 9.2, 15.3 6.6-4.1+ 2.5 26 SacIl LSC; Pet9.0, 9.2, 15.3 15.0-10.0+ 5.0 27 SacIl LSC; Pet9.0, 9.2, 15.3 13.0-6.0+ 7.0 28 EcoRI LSC; Pet9.0, 9.2, 15.3 9.0-5.0+ 4.0 29 BanI LSC; Pet9.0, 9.2, 15.3 3.2-2.5 + 0.7 30 BanII LSC; Pet9.0, 9.2, 15.3 11.7-4.2+ 7.5 31 AvaIl LSC; Sac 3.8,6.9, 7.7 4.4-3.5 + 0.8 32 BstEII LSC; Sac 3.8,6.9, 7.7 15.0-12.2+ 2.8 33 BstEII LSC; Sac 3.8,6.9, 7.7 15.0-7.0+ 8.0 34 BstXI LSC; Sac 3.8,6.9, 7.7 8.5-7.0+ 1.5 35 BstXI LSC; Sac 3.8,6.9, 7.7 8.5-4.5+ 4.0 36 BstXI LSC; Sac 3.8,6.9, 7.7 10.0-8.5+ 1.5 37 BglI LSC; Sac 10.6,4.6, 5.4, 6.3 20.0-12.0+ 8.0 38 BanIl LSC; Sac 10.6,4.6, 5.4, 6.3 4.0-2.5+ 1.5 39 EcoRV LSC; Sac 10.6,4.6, 5.4, 6.3 2.0-1.8+ 0.2 40 EcoRI LSC; Sac 10.6,4.6, 5.4, 6.3 5.0-2.4+ 2.6 41 BstXI LSC; Sac 10.6,4.6,5.4,6.3 12.0-10.5+ 1.5 42 AvaIl LSC; Sac 10.6,4.6,5.4,6.3 4.3-1.8+ 1.6 + 0.9 43 BanIl LSC; Sac 10.6,4.6,5.4,6.3 18.0-12.0+ 6.0 44 AvaI LSC; Sac 3.8,6.9, 7.7 7.0-5.5+ 1.5 45 EcoRI LSC; Pet9.0, 9.2, 15.3 5.8-5.0+ 0.8 46 HaeII LSC; Sac 3.8,6.9 1.7-1.0+ 0.7 47 EcoRI rDNA 8.0-6.0+ 2.0 48 EcoRI rDNA 8.0-7.0+ 1.0 49 BstEII rDNA 11.0-8.0+ 3.0
This content downloaded from 160.111.254.17 on Wed, 7 May 2014 16:16:56 PM All use subject to JSTOR Terms and Conditions 1996] SOLTIS ET AL.: SCHIEDEA AND ALSINIDENDRON 369 theSchiedea-Alsinidendron complex; only 18 cpDNA Alsinidendronspecies; half of the trees show S. restrictionsite mutations were parsimony-informa- membranacea as sisterto all otherspecies of Schiedea tivewithin Schiedea and Alsinidendron.The remain- (i.e., Schiedeais monophyletic)because of a single ing restrictionsite mutationswere autapomor- cpDNA mutationshared by S. membranaceaand all phies.Three restriction site changes in rDNA were otherSchiedea species. also detected, all of which were parsimony- Withthe exception of S. membranacea,all species informativewithin the Schiedea-Alsinidendroncom- of Schiedeaconsistently form a well-supported plex (Appendix 1). Resultsof the skewnesstest monophyleticgroup (bootstrapvalue of 100%, conducted on the cpDNA restrictionsite data decay value of 4), with S. spergulinaappearing as suggestconsiderable nonrandom structure of the the sisterto the remainingspecies, althoughthis data. Thegi value forthe cpDNA data setis - 1.617 sister-grouprelationship is not supportedby all (p < 0.01;Hillis and Huelsenbeck1992). Parsimony mostparsimonious trees. Relationships within this analysis of only the cpDNA restrictionsite data large clade are poorly resolved due to the small resultedin 2,014most parsimonious trees, each of number of restrictionsite mutations detected 50 steps,with a consistencyindex (CI), excluding withinthe complex, but twoclades are noteworthy. uninformativecharacters, of 0.886 and a retention Althoughpresent in only63% of the shortesttrees index(RI) of0.943. and weakly supportedby the bootstrapanalysis The rDNA mutationsdo not conflictwith the (value of 22%),one clade comprisesS. ligustrina,S. cpDNA restrictionsite data, but ratherfurther adamantis,S. salicaria,S. lydgatei,S. kealiae,and S. resolveor supportrelationships suggested by the apokremnos.This clade is similarto themorphologi- cpDNA analysis. One of the rDNA mutations cally-definedS. adamantisclade of Wagneret al. supportsthe strong relationship between A. trinerve (1995) and Weller et al. (1995), lacking only S. and A. obovatumsuggested by cpDNA data, and a haleakalensisand including S. kealiae,and will secondrDNA mutationfurther supports the mono- hereafterbe referredto as the S. adamantisclade. phylyof Alsinidendron (see Fig. 1). The thirdrDNA Withinthe S. adamantisclade, a close relationshipis mutationsuggests a close relationshipamong S. suggestedbetween S. salicariaand S. lydgatei,with a pubescens,S. nuttallii,S. diffusa,and S. kaalae,whose bootstrapvalue of 60% and a decay value of 1. A relationshipswere unresolvedbased on cpDNA second clade,marked by one rDNA restrictionsite data. The skewnesstest on the combinedcpDNA mutation,is composedof S. pubescens,S. nuttallii,S. and rDNA data set also indicated significant diffusa,and S. kaalae.This clade is comparableto the nonrandomstructure in thedata (g1= -1.690; p < S. nuttalliiclade of Wagneret al. (1995) and Weller 0.01; Hillis and Huelsenbeck1992). Phylogenetic et al. (1995), differingonly in the addition of S. analysis of the molecular data produced 870 implexaand S. sp.nov. in themorphologically-based shortesttrees, each of 53 steps,with a CI of 0.895 trees(Fig. 2). (excludinguninformative characters) and a RI of PhylogeneticAnalysis ofAbridged Morphologi- 0.947. cal Data Set. To obtainphylogenetic trees based The 50% majority-ruletree for the combined on morphologicaldata, we used thedata of Weller cpDNA/rDNA data set (Fig. 1) supports (100% et al. (1995)and omittedthose taxa forwhich DNA bootstrapvalue, decayvalue of 13) themonophyly data were not available.The majority-ruleconsen- of the Schiedea-Alsinidendronlineage, relative to the sus tree forthe abridgedmorphological data set outgroupsused, with several clades presentwithin (treenot shown) is topologicallynearly identical to thisassemblage. One clade,hereafter referred to as thatobtained by Welleret al. (1995;Fig. 2), differing theS. membranaceaclade (terminologyof Wagner et only in the placementof the nine species omitted al. 1995;Weller et al. 1995),comprises S. membrana- fromthe abridged tree. The fourmajor clades noted cea,as well as thethree species of Alsinidendron (Fig. previouslyare stillpresent: the S. membranacea,S. 1). This clade appears as the sisterto all other adamantis,S. nuttallii,and S. globosaclades. speciesof Schiedea. Within the S. membranaceaclade, PhylogeneticAnalysis of CombinedMolecularl themonophyly of the three species of Alsinidendron Morphological Data Set. The skewnesstest indi- is well-supported(bootstrap value of 97%, decay cated significantnonrandom structure in thecom- value of 3), as is the sister-groupstatus of A. bined molecularand morphologicaldata set (g1 = obovatumand A. trinerve(bootstrap value of 96%, -1.245; p < 0.01; Hillis and Huelsenbeck 1992). decay value of 3). However, only one cpDNA Phylogeneticanalysis of this data set resultedin 20 mutation links S. membranaceawith the three shortesttrees, each of 166 steps(CI = 0.610exclud-
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Silene Moehringia Outgroups
A. lychnoides 100 9 1 A. trinerve| 50 96,3 A. obovatum c 46 S. membranacea j
______S. spergulina 100 100,13 _ S. globosa 850 S. kealiae 862 63 100 26 S. kealiae 791 100,4 S. adamantis
75 63 100 S. lydgatei 44 22 60,1 I S. salicaria
S. apokremnos
S. ligustrina
S. globosa 852
S. globosa 844 51 37 S. haleakalensis
S. menziesii
S. mannii
S. hookeri
S. kaalae
S. nuttaliia
66,1 S. pubescens s c S. diffusa
FIG. 1. Majority-ruleconsensus of 870 most parsimonioustrees resulting from analysis of cpDNA and rDNA restrictionsite data. The analysisof cpDNA data aloneproduced the identical topology except that the S. nuttalliiclade is not recognized(see text).Numbers above branchesare the percentageof these870 treesthat support the branches; numbersbelow branchesare bootstrappercentages and decay values (bold), respectively.Clades not presentin all shortesttrees have a decayvalue of0. inguninformative characters; RI = 0.725).The strict all but fourof the branchesappear in all of the consensustree (Fig. 3) is topologicallyvery similar shortesttrees. The S. membranacea,S. adamantis, and to thoseobtained in the separateanalyses of DNA S. nuttalliiclades are again present;however, as in and morphologicaldata but is morefully resolved theDNA analysis,members of the morphologically- than the DNA strictconsensus tree. Furthermore, based S. globosaclade (S. kealiae,S. globosa,S. hookeri,
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Outgroup Minuartiahowellii * Minuartiadouglasii * S. amplexicaulis* S. stellarioides* S. helleri*
58 ~~~~~~~~~~S.membranacea S. verticillata* A. lychnoides A. viscoslm* 82 A. obovatum 60 84 1 A. trinerve S. apokremnos S. adamantis S. haleakalensis 52 S. ligustrina S. lydgatei 87 S. salicaria S. sp. nov.* S. implexa* S. nuttalliivar. pauciflora * ~~~~~ ~~~S. nuttalliivar. nuttallii _ S. kaalae S. diffusa 93 I S. pubescens S. mannii S. spergulina S. attenuata* 58 S. globosa S. kealiae S. sarmentosa* S. hookeri S. menziesii
FIG. 2. Strictconsensus of six mostparsimonious trees resulting from analysis of morphological data (fromWeller et al. 1995).Numbers below branches are bootstrap percentages; nodes lackingbootstrap values received< 50% bootstrap support.Asterisks designate those species not included in DNA analyses.
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Outgroup A. lychnoides
100, 9 A. obovatum
89, 3 | A. trinerve S. membranacea
S. adamantis
S. apokremnos
S. haleakalensis 52,1 S. ligustrina 1 o S. lydgatei 12, 1 A , 2 S. salicaria
S. mannii 6,1 S. spergulina
7,.1 S. kealiae
10,.1 S. menziesii S. hookeri
S. globosa
95, 6 I S. diffusa ~ 3S. pubescens 91, 3 S. kaalae | t u
S. nuttalliivar. nuttallii
FIG. 3. Strictconsensus of 20 most parsimonioustrees resultingfrom analysis of a combinedmolecular and morphologicaldata set.Numbers below branches are bootstrap percentages and decayvalues (bold),respectively.
S. mannii,S. menziesii,and S. spergulina)do notform Moleculardata suggesta well-supportedSchiedea- a monophyleticgroup. In the combinedanalysis, Alsinidendronclade relativeto theoutgroups Moeh- theyare part of a largeclade withinwhich is nested ringialateriflora and Silenestruthioloides. The mono- theS. adamantisclade. phylyof the Schiedea-Alsinidendronlineage should be furthertested, however,as part of a more comprehensivemolecular study of genera of Caryo- DISCUSSION phyllaceae,including Minuartia, now believed on PhylogeneticRelationships Based on DNA Data. morphologicalgrounds to be most closelyrelated Phylogeneticanalyses of cpDNA restrictionsite to theSchiedea-Alsinidendron complex (Wagner et al. data alone (treenot shown) and of the combined 1995). Nonetheless,these results are in agreement cpDNA/rDNA restrictionsite data (Fig. 1) pro- withmorphological data (Welleret al. 1990,1995) duced congruenthypotheses of relationships in the thatsimilarly indicate that Alsinidendron and Schiedea Schiedea-Alsinidendroncomplex. Because the three forma well-supportedmonophyletic group. Mor- rDNA mutationsdo notcontradict, but rather agree phologically,these two genera are unusual in withor complement,the cpDNA data,we will limit Caryophyllaceaein that theypossess specialized our discussion to the most parsimonioustrees floralnectaries and lackpetals (Wagner et al. 1995). resultingfrom the analysis of the combined Withinthe Schiedea-Alsinidendroncomplex, rela- cpDNA/rDNAdata (Fig.1). tionshipsare generallypoorly resolved based on
This content downloaded from 160.111.254.17 on Wed, 7 May 2014 16:16:56 PM All use subject to JSTOR Terms and Conditions 1996] SOLTIS ET AL.: SCHIEDEA AND ALSINIDENDRON 373 molecular data due in part to a paucity of Welleret al. (1995). The DNA-based S. adamantis re-strictionsite mutations. Despite the small num- clade differsfrom its morphologically-basedcoun- berof informative restriction site mutations, several terpartonly in theabsence of S. haleakalensisand the lineages are apparent within the complex, and inclusionof S. kealiaein thisclade in themolecular theseagree in largepart with clades recoveredby tree.The morphologically-basedcladistic analysis phylogeneticanalysis of morphologicalcharacters (Welleret al. 1995)places S. kealiaein whatWeller et (Fig. 2; Welleret al. 1995). The threespecies of al. termthe S. globosaclade (S. globosa,S. attenuata Alsinidendronform a well-supportedlineage based W. L. Wagner,Weller & Sakai,S. hookeri,S. menziesii, on moleculardata. Thesethree species of Alsiniden- S. sarmentosaDegener & Sherff,S. kealiae,S. dron,together with S. helleriSherff, S. membranacea,spergulina, and S. mannii).Because both the DNA- based S. adamantisclade and morphologically- S. stellarioidesH. Mann,and S. verticillataF. Brown, based S. globosaclade are onlyweakly supported, compose the S. membranaceaclade in the morpho- thediscrepancy in theplacement of S. kealiaecould logically-basedcladistic analysis (Fig. 2; Wagneret easily be the result of homoplasy in eitherthe al. 1995; Welleret al. 1995). Of the five Schiedea molecularor morphologicaldata set.The combined speciespresent in theS. membranaceaclade based on analysisplaces S. haleakalensisin the S. adamantis morphology,leaf materialof only S. membranacea clade and excludesS. kealiae,recovering a clade that and S. verticillatawas available at the timeof this closelyresembles that found in the morphological study,and DNA ofS. verticillataproved intractable. analysis. The position of S. membranaceais uncertain, Althoughthe morphologically-basedS. globosa however,based on DNA data. One cpDNA restric- clade is weakly supported,morphological data tion site mutation unites S. membranaceawith suggesta close relationshipbetween S. kealiaeand speciesof Alsinidendron, whereas a second cpDNA S. sarmentosa,S. hookeri,and S. menziesii.The mutationunites S. membranaceawith all other discrepancyin the placementof S. kealiaein the speciesof Schiedea.A S. membranaceaclade compa- morphologicaland moleculartrees may not reflect rable to thatof Welleret al. occursin 50% of the real conflictbetween the data sets because in shortest trees, making Schiedea paraphyletic, neitheranalysis is theposition of S. kealiaestrongly whereasthe second topologysuggests that Alsini- supported. However, the differencemay result dendronand Schiedeaare each monophyleticand fromdifferent nuclear and organellarhistories in S. sistertaxa. Thus, at thispoint, molecular data are kealiae.The chloroplastgenome of S. kealiaemay inconclusiveregarding the proposed paraphyly of have been obtained from a member of the S. Schiedeabased on morphologicaldata. Although adamantisclade. BothS. kealiaeand S. ligustrina(of the placementof S. membranaceais problematic in the S. adamantisclade) occur in the Waianae the DNA trees,S. membranaceaclearly possesses Mountainson O'ahu, providingthe opportunity for manysymplesiomorphic restriction sites also found the transferof the S. ligustrinachloroplast genome in Alsinidendronand lacksthe five synapomorphies to S. kealiae.Hybridization in thecomplex is known thatdefine the monophyletic remainder of Schiedea. fortwo otherspecies pairs (S. Wellerand A. Sakai, Hence,molecular and morphologicaldata agreein unpubl.data), althoughhybridization involving S. kealiaehas notbeen reported. thegeneral composition and phylogeneticposition The third DNA-based clade (S. pubescens,S. of the S. membranaceaclade, althoughthe exact nuttallii,S. diffusa,and S. kaalae)is identicalto the placement of S. membranaceain the molecular morphologically-basedS. nuttallii clade ofWeller et analysisis uncertain.The position of S. membranacea al. (1995) withtwo exceptions.Schiedea implexa, an could be stabilized in the molecular perhaps extincttaxon thatcould not be sampled forDNA analysis with the inclusionof additionalspecies variation,is also a memberof the morphological S. (i.e., S. stellarioides,S. helleri,and S. verticillata) nuttalliiclade. In addition,the S. nuttalliiclade shown in the morphologicalstudy (Welleret al. inferredfrom morphology also containsa recently 1995) to be partof the S. membranaceaclade, along discoveredand currentlyundescribed species, for withS. membranaceaand Alsinidendron. which leaf materialwas not available for DNA A second weakly-supportedlineage based on analysis. DNA data consistsof S. ligustrina,S. adamantis,S. One ofthe most obvious differences between the salicaria,S. lydgatei,S. kealiae,and S. apokremnos,a DNA-based and morphologically-basedphyloge- clade nearlyidentical to the S. adamantisclade of netic trees is that the formerdo not reveal a S.
This content downloaded from 160.111.254.17 on Wed, 7 May 2014 16:16:56 PM All use subject to JSTOR Terms and Conditions 374 SYSTEMATIC BOTANY [Volume 21 globosaclade (S. globosa,S. attenuata,S. hookeri,S. Evolutionof BreedingSystems. In the sections menziesii,S. sarmentosa,S. kealiae,S. spergulina,and thatfollow, we will addressquestions of breeding- S. mannii).These species are part of a large systemevolution, habitat shifts, and biogeography polytomyin treesbased on DNA data (Fig. 1) and based on the phylogenetictrees for the Schiedea- are unitedby onlya singlecharacter, the presence Alsinidendroncomplex. The treesbased on molecu- oflong, attenuate leaf tips, in themorphologically- lar data onlyand thosederived from the combined based trees. It is, therefore,the most weakly- molecularand morphologicaldata set are largely supportedalliance based on morphology(Wagner congruent.Because ofthis congruence and because et al. 1995; Weller et al. 1995). Furthermore,S. thetrees from the combined analysis are morefully globosaitself does not appear monophyleticin the resolved and have higherinternal support than DNA tree,with population850 appearingas the thosebased onlyon DNA data,we will base these sisterto the large clade of Schiedeaspecies that discussionson the strictconsensus tree resulting includes two other populations of S. globosa. fromthe combined analysis (Fig. 3). Althoughthis placementof S. globosais weakly Mapping breeding-systemdiversity onto the supported,the three populations of S. globosafail to morphologically-basedtree indicates that sexual forma monophyleticgroup in thestrict consensus dimorphism(gynodioecy, subdioecy, and dioecy) ofall shortestmolecular-based tress; they form part evolved from one to six times, depending on ofa 13-chotomy.However, populations 850 and 844 whetherbreeding systems are coded as monomor- appear in the same small clade in a phylogenetic phic vs. dimorphicor, alternatively, as hermaphro- analysis of sequences of the internaltranscribed ditic, gynodioecious,subdioecious, or dioecious spacers of nuclearrDNA (P. Soltis et al., unpubl. (Weller et al. 1995). Although breeding-system data). characterswere not includedin themorphological PhylogeneticAnalysis of the Combined Morpho- analyses,subsequent inclusion of thesecharacters logical and Molecular Data Set. Phylogenetic had littleeffect on topologyor theinterpretation of analysisof a combinedmorphological and molecu- breeding-systemevolution. Weller et al. (1995) lar data set(Fig. 3) providedresults similar to those concluded that two transitionsto sexual dimor- obtained via the analysis of cpDNA and rDNA phism are most likely and that one to several restrictionsites (Fig. 1) in that threeof the four reversalsfrom dimorphism to hermaphroditism major clades of Weller et al. (1995) are again also occurred. present:the S. membranaceaclade, the S. adamantis Mapping the breedingsystems, as summarized clade, and the S. nuttalliiclade. Membersof the S. in Table 1, ontothe molecular tree (Fig. 1) provides globosaclade (Welleret al. 1995) do not forma an equivocal interpretationof the evolution of monophyleticgroup in thecombined analysis, but sexual dimorphismbut does not contradictthe instead are part of a clade out of which the S. interpretationsbased only on morphologicaldata adamantisclade is derived.In thecombined analysis (Welleret al. 1995). Scoringbreeding systems as (Fig. 3), the problematicS. kealiae(part of the S. sexuallymonomorphic vs. dimorphic(i.e., scoring globosaclade based on morphology,but a member gynodioecy,subdioecy, and dioecyas a singlestate; of the S. adamantisclade in the DNA analyses) is see Welleret al. 1995),the combined morphological also partof this large clade. and molecular analysis implies two origins of Boththe S. nuttalliiand S. membranaceaclades are sexual dimorphism,once in S. globosaand once in stronglysupported in thecombined morphological the ancestorof the large clade thatcomprises the and molecularanalysis, with bootstrapvalues of remainingeight sexually dimorphic species. This 91% and 89%, respectively,and each witha decay interpretationrequires a singlereversal to hermaph- value of 3. In contrast,the monophylyof the S. roditismin S. lydgatei.An interpretationthat is one adamantisclade is only weakly supported(boot- step longer involves a single origin of sexual strap value of 52%, decay value of 1). Strongly- dimorphismin the ancestorof the sistergroup of supportedrelationships are also suggestedfor: 1) theS. nuttalliiclade, with independent reversals to the threespecies of Alsinidendron(bootstrap value hermaphroditismin S. hookeri,S. menziesii,and S. of 100%,decay value of 9); 2) A. obovatumand A. lydgatei.Multi-state coding of breeding systems and trinerve(95%, 5), and 3) S. diffusaand S. pubes- orderedtransitions from hermaphroditism to dio- cens (94%, 3). Also stronglysupported is the ecy,with gynodioecy and subdioecyas intermedi- monophylyof Schiedea,minus S. membranaceaates (Charlesworthand Charlesworth1978), results (bootstrapvalue of95%, decay value of6). in a more complex picture of breeding-system
This content downloaded from 160.111.254.17 on Wed, 7 May 2014 16:16:56 PM All use subject to JSTOR Terms and Conditions 1996] SOLTIS ET AL.: SCHIEDEA AND ALSINIDENDRON 375 evolution,with changes to hermaphroditism,gyno- logically-basedS. globosaclade) raisethe possibility dioecy,and dioecyfrom a subdioeciousancestor all of an originfor the complexon O'ahu (Fig. 4B), takingplace withinthe S. adamantisclade. ratherthan on Kaua'i or even older islands as Habitat Shifts. Trees based on the combined suggestedby Wagneret al. (1995). Based on the analysisimply a simplerpattern of habitat diversifi- strictconsensus tree from the combined morphologi- cation in the Schiedea-Alsinidendroncomplex than cal and molecular analysis, an origin for the do treesbased on eithermorphological or molecu- complex on Kaua'i (Fig. 4A) requiresperhaps a lar data alone. All of thecombined trees suggest a single migrationto O'ahu in the ancestorof the single shiftto dry habitatsin the ancestorof the sister group to the S. membranaceaclade, with large clade comprisingthe S. adamantisclade and subsequentshifts to otherislands to accountfor the the membersof the S. globosaclade, with a single distributionsof the remainingspecies. This sce- shiftback to a mesichabitat in S. hookeri.The habitat nario involvesfewer steps (13) than independent occupiedby theancestral members of thecomplex radiationsfrom Kaua'i forthe S. membranacea,S. is uncertain.The closestrelatives of Schiedeaand nuttallii,and S. adamantisclades (17 steps, not Alsinidendron,based on morphology,occur in shown). An origin of the complex on O'ahu, relativelydry habitats, suggesting that the ancestor followed by several independentmigrations to ofthe Schiedea-Alsinidendron lineage may have also Kaua'i and to otherislands (13 steps; Fig. 4B), is occupieddry habitats. This would requirea shiftto equally parsimonious to an origin on Kaua'i mesic habitatsearly in the historyof the lineage, followedby an earlymigration to O'ahu (Fig. 4A). beforethe divergenceof the S. membranaceaclade However, an origin of the complex on O'ahu fromthe remainder of Schiedea. Alternatively, ifthe requiresfour or five"back colonizations"to older S. membranaceaand S. nuttalliiclades are truly islands (i.e., Kaua'i) whereas an originon Kaua'i successivesister groups to the remainderof the (followedby a migrationto O'ahu in theancestor of complex,then the ancestormay have occupied a the sister group of the S. membranaceaclade) mesichabitat because bothbasal lineagesoccur in suggestsonly three, for S. nuttallii,S. spergulina,and mesicor wet habitats. S. apokremnos.Finally, because themorphologically- Biogeography. Using the most parsimonious based S. globosaclade was not recoveredin either trees for Schiedeaand Alsinidendronbased on the molecular or combined analyses (perhaps cladistic analyses of morphologicalcharacters, because of undersamplingof the potentialmem- Wagneret al. (1995)suggested that the S. membrana- bers of this clade in the latterstudies), inferred cea,S. adamantis,and S. nuttalliiclades all originated patternsof colonization,particularly of O'ahu, on Kaua'i, theoldest of the current main Hawaiian differbetween the morphological analysis and the Islands. Furthermore,if we consider only these molecularand combinedanalyses. Expanded mo- threeclades, analysesof both the moleculardata lecularand combinedanalyses might resolve more and the combinedmolecular and morphological fullythe relationships in thisportion of the tree and data do notcontradict this hypothesis, and molecu- provide a clearerpicture of patternsof dispersal lar data generallysupport the conclusion (Wagner and colonization. et al. 1995)that colonization events in Schiedeaand Wagneret al. (1995) furthersuggested that the Alsinidendronhave proceededfrom older to youn- originof the Schiedea-Alsinidendroncomplex was a gerislands. Schiedea membranacea and Alsinidendronrelatively old event,with the originalcolonization lychnoidesare the basal membersof the S. membrana- ofthe archipelago occurring on islandsthat are now cea clade and are restrictedto Kaua'i, and the S. severelyeroded and subsided.The S. membranacea membranaceaclade is the sisterto all othertaxa in clade may thereforerepresent the remnants of this the complex.However, relationships within both originaldiversification within the complex. One theS. nuttalliiand S. adamantisclades aretoo poorly strikingfeature, however, of the molecular analysis resolved to permit analysis of the patternsof is thepaucity of restrictionsite mutations for both colonizationin theseclades. cpDNA and rDNA. Similarly,ITS sequenceanalysis Althoughmolecular analyses generally support (P. Soltiset al., unpubl.data) revealsvery few base an originof the S. membranacea,S. adamantis, and S. substitutionsamong these species. These results are nuttalliiclades on Kaua'i (Fig. 4A), more complex in contrastto theresults of both cpDNA restriction scenariosare required when the phytogeography of site surveysand ITS sequence data forHawaiian theentire complex is considered.The distributions silverswords(Baldwin et al. 1990;Baldwin 1992), a of theremaining species (membersof themorpho- group of endemics typifiedby higherlevels of
This content downloaded from 160.111.254.17 on Wed, 7 May 2014 16:16:56 PM All use subject to JSTOR Terms and Conditions 376 SYSTEMATIC BOTANY [Volume 21
A. Originon Kaua'i Outgroup A. lychnoides K 1 I A.obovatum 0 A. trinerve 0 S. membranacea K
K S. adamantis 0 10MN S. apokremnos K S. haleakalensis M S. ligustrina 0 MN S. lydgatei Mo S. salicaria M
K S. mannii 0 S. spergulina K
MN S. kealiae 0 S. menziesii L, M
MN S. hookeri 0
O m MN H S. globosa 0, Mo, M . H S.diffusa Mo, M, H S. pubescens 0, Mo,L, M
K MN S. kaalae 0 S. nuttalliivar. nuttallii 0, K, Mo,M B. Originon O'ahu
K Outgroup A. lychnoides K A. obovatum 0
K A. trinerve 0 S. membranacea K K S. adamantis 0
M . apokremnos K m S. haleakalensis M S. ligustrina 0 S. lydgatei Mo S. salicaria M
K S. mannii 0 -U S. spergulina K S. kealiae 0 I LS. menziesii L, M S. hookeri 0
MN H S. globosa 0, Mo,M S. diffusa Mo,M, H S. pubescens 0, Mo, L, M
K MN S. kaalae 0 S. nuttallii var. nuttallii 0, K, Mo, M
This content downloaded from 160.111.254.17 on Wed, 7 May 2014 16:16:56 PM All use subject to JSTOR Terms and Conditions 19961 SOLTIS ET AL.: SCHIEDEA AND ALSINIDENDRON 377 molecular diversity.Most of the restrictionsite dron. For example, several key species of the mutationsdetected herein actually differentiatemorphologically-based S. membranaceaclade (S. species of Alsinidendronfrom species of Schiedea. stellarioides,S. helleri, and S. verticillata)could notbe Even the position of S. membranaceaas sisterto included in the molecularanalysis. The relation- Alsinidendronin the molecular analysis is equivocal, ships of thesespecies mustbe ascertainedprior to withhalf of the shortest trees also showingSchiedea furtherassessments of rates of molecular evolution as monophyletic.Thus, assuminga monophyletic or the patternsand timingof speciationin the Schiedea(this alternative is notdepicted in Fig. 1) Schiedea-Alsinidendroncomplex. and a rough molecular clock, molecular data Conclusions. Althoughfew restriction site mu- support Wagner et al.'s (1995) hypothesisthat tationswere identifiedin eitherthe cpDNA or species of Alsinidendron,with theiraccumulated rDNA of Schiedeaand Alsinidendron,the resulting restrictionsite mutations,represent an older lin- phylogenetictrees were largely consistentwith eage and perhaps are remnantsof the original thosebased on morphology.The combinedanalysis diversificationof the complex on the Hawaiian of morphologicaland molecular characterscan Islands. The paucityof restrictionsite mutations often provide furtherresolution and stronger outsideof Alsinidendron might then suggest that the support for some of the internalbranches than remainderof the complex (i.e., most species of eitherdata set did alone (cf. Barrettet al. 1991; Schiedea)is theresult of a relativelyrecent and rapid reviewed by de Queiroz et al. 1995). Given the diversification.However, the combined morphologi- greaterresolution of the combined tree, patterns of cal/molecularanalysis stronglysupports the S. breeding-systemevolution and habitatshifts are membranaceaclade as thesister to all otherspecies of muchsimpler than those proposed by Wagneret al. Schiedea,making Schiedea paraphyletic. If Schiedea is (1995) and Weller et al. (1995). The combined indeed paraphyletic(as shown in Figs. 1, 3), analysis implies that sexual dimorphismarose Alsinidendroncannot represent an ancientlineage eithertwice in the complex,with one reversalto separatefrom S. membranacea(and perhaps other hermaphroditismin S. lydgatei,or only once,with species as shown in the morphologicalanalysis threereversals to hermaphroditism.A singleshift alone; Fig. 2). Age alone could thereforenot be to dry habitats more or less accompanied this responsiblefor the greatercpDNA divergenceof changein breedingsystem, with a singleshift back Alsinidendron.Alternatively, species of Alsiniden- to a mesic habitat in S. hookeri.Patterns of dronmay experienceaccelerated rates of cpDNA colonizationremain uncertain, with origins for the evolution.All speciesof Alsinidendron have autoga- complexon Kaua'i and O'ahu equallylikely. mous breedingsystems, a traitthat may lead to rapid generationtime and increased rates of ACKNOWLEDGMENTS.We thankthe National Science molecularevolution (e.g., Britten 1986; Gaut et al. Foundation(BSR 88-17616,BSR 89-18366,DEB 92-07724), 1992).In contrast,species of Schiedea appear to have theNational Geographic Society, and theScholarly Studies longer reproductivecycles characterizedby out- Programof the Smithsonian Institution for support of this crossing.If rates of molecular evolution are depen- research.SGW was supportedby a SmithsonianMellon dent on generationtime, the longerlife cycles of Fellowship.Helene Van preparedthe figures.We thank Bob Kuzofffor valuable technicalassistance, and two these Schiedeaspecies may reduce the rate of anonymous reviewers for helpful commentson the molecular evolution,as reflectedin the lower manuscript.Joan Aidem, Melany Chapin,Tom Egeland, moleculardiversity observed outside the S. membra- BruceEilerts, Tim Flynn,Norm Glenn, Bill Haus, Robert naceaclade. Finally,limited sampling of key taxa Hobdy,Guy Hughes,Ken Inoue,Joel Lau, Lloyd Loope, mayalso affectour inferencesof rates and patterns David Lorence,John Obata, Art Medeiros, Steve Perlman, of moleculardivergence in Schiedeaand Alsiniden- LymanPerry, Diane Ragone,Talbert Takahama, Wayne
FIG. 4. Possiblebiogeographic scenarios based on strictconsensus tree shown in Fig.3. 4A. Beginningwith origin on Kaua'i; requires13 stepsafter the origin of the complex. 4B. Beginningwith origin on O'ahu; requires13 stepsafter the originof thecomplex. Note thatthe migration pattern depicted in theS. membranaceaclade is one of two possibilities. Darkrectangles indicate shifts to youngerislands (H = shiftto Hawai'i; K = shiftto Kaua'i; MN = colonizationof some or all islandsof Maui Nui; 0 = shiftto O'ahu). Open rectanglesrepresent "back colonizations" to olderislands. Letters to theright of the species names designate the distributions of the species (H = Hawai'i; K = Kaua'i; L = Lana'i; M = Maui; Mo = Moloka'i;0 O'ahu).
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Takeuchi,Patti Welton, and Ken Wood providedinvalu- reliabilityin molecularphylogenetic analyses. Jour- able help in the field.We thankthe National Tropical nal ofHeredity 83: 189-195. BotanicalGarden, Lawai, Hawaii, fortheir support of this HUELSENBECK,J.P. 1991.Tree-length distribution skewness: research.We also thankK. Holsingerfor helpful comments an indicatorof phylogenetic information. Systematic on themanuscript. Zoology40: 257-270. JANSEN,R. K. and J. D. PALMER 1987. ChloroplastDNA fromlettuce and Barnadesia(Asteraceae): structure, LITERATURE CITED gene localization,and characterizationof a large BALDWIN, B. G. 1992.Phylogenetic utility of the internal inversion.Current Genetics 11: 553-564. transcribedspacers of nuclear ribosomalDNA in MADDISON,D. R. 1991.The discoveryand importanceof plants:an examplefrom the Compositae. Molecular multipleislands of most parsimonious trees. System- Phylogeneticsand Evolution1: 3-16. aticZoology 40: 315-328. , D. W. KYHOS,and J. DVORAK.1990. Chloroplast PALMER,J. D. 1986. Isolationand structuralanalysis of DNA evolutionand adaptiveradiation in theHawai- chloroplastDNA. Methods in Enzymology 118: ian silverswordalliance (Asteraceae-Madiinae).An- 167-186. nals ofthe Missouri Botanical Garden 77: 96-109. RIESEBERG,L. H., D. E. SOLTIS,and J.D. PALMER 1988. A BARRETT,M., M. J.DONOGHUE, and E. SOBER 1991.Against molecular reexamination of introgression between consensus.Systematic Zoology 40: 486-493. Helianthusannuus and H. bolanderi(Compositae). BAUM, D. A., K. J. SYTSMA,and P. C. HOCH. 1994. A Evolution42: 227-238. phylogeneticanalysis of Epilobium(Onagraceae) SOLTIs, D. E., P. S. SOLTIs, T. G. COLLIER, and M. L. based on nuclearribosomal DNA sequences.System- EDGERTON.1991. ChloroplastDNA variationwithin aticBotany 19: 363-388. and amonggenera of theHeuchera group (Saxifraga- BREMER,K. 1988.The limitsof amino acid sequencedata in ceae): evidence for chloroplasttransfer and para- angiospermphylogenetic reconstruction. Evolution phyly.American Journal of Botany 78: 1091-1112. 42: 795-803. SWOFFORD,D. L. 1991.PAUP: Phylogeneticanalysis using BRITTEN,R. J.1986. Rates of DNA sequenceevolution differ parsimony,version 3.1.1. Champaign: Illinois Natural betweentaxonomic groups. Science 231: 1393-1398. History Survey. CHARLESWORTH, B. and D. CHARLESWORTH. 1978.A model WAGNER,W. L., S. G. WELLER,and A. K. SAKAI. 1995. forthe evolution of dioecy and gynodioecy.American Phylogeny and biogeography in Schiedea and Alsini- Naturalist112: 975-997. dendron(Caryophyllaceae). Pp. 221-258 in Hawaiian DOYLE, J.J. and J.L. DOYLE. 1987.A rapid DNA isolation biogeography:Evolution on a hot-spotarchipelago, eds. W. procedurefor small amounts of freshleaf tissue. L. Wagner and V. A. Funk. Washington, D.C.: PhytochemicalBulletin 19: 11-15. Smithsonian InstitutionPress. FELSENSTEIN,J. 1985. Confidence limits on phylogenies:an WELLER,S. G. and A. K. SAKAI. 1990. The evolution of approachusing the bootstrap. Evolution 39: 783-791. dicliny in Schiedea (Caryophyllaceae), an endemic GAuT,B. S.,S. V.MUSE, W. D. CLARK,and M. T. CLEGG.1992. Hawaiian genus. Plant Species Biology 5: 83-95. Relativerates of nucleotidesubstitution at the rbcL f , W. L. WAGNER,and D. R. HERBST. 1990. locusof monocotyledonous plants. Journal of Molecu- Evolution of dioecy in Schiedea (Caryophyllaceae: larEvolution 35: 292-303. Alsinoideae) in the Hawaiian Islands: biogeographi- HILLIS,D. M. 1991.Discriminating between phylogenetic cal and ecological factors. Systematic Botany 15: signal and random noise in DNA sequences. Pp. 266-276. 278-294in Phylogeneticanalysis of DNA sequences,eds. W. L. WAGNER, and A. K. SAKAI. 1995. A M. M. Miyamotoand J. Cracraft.Oxford: Oxford phylogenetic analysis of Schiedea and Alsinidendron Univ.Press. (Caryophyllaceae: Alsinoideae): implications for the and J. P. HUELSENBECK.1992. Signal, noise, and evolution of dioecy. Systematic Botany 20: 315-337.
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