trnL-F Spacer Research Articles

An overview of the phylogenetic relationships within Epidendroideae inferred from multiple DNA regions and recircumscription of Epidendreae and Arethuseae (Orchidaceae)

Phylogenetic relationships within the epidendroid orchids with emphasis on tribes Epidendreae and Arethuseae were assessed with parsimony and model-based analyses of individual and combined DNA sequence data from ITS nuclear ribosomal DNA and plastid trnL intron, the trnL-F spacer, matK (gene and spacers), and rbcL regions. Despite the absence of boostrap support for some of the relationships, a well-resolved and supported consensus was found, for which most clades were present in more than one individual analysis. Most clades of this consensus attained high posterior probabilities with a Bayesian approach. Circumscription of Arethuseae and Epidendreae are different from most orchid systems based on morphology, but they correspond to a combination of patterns from several less comprehensive orchid phylogenetic analyses previously published. A new circumscription of Epidendreae includes only Neotropical subtribes (Bletiinae, Chysiinae, Laeliinae, Ponerinae, and Pleurothallidinae), whereas Arethuseae include Coelogyninae (all Old World) and Arethusinae (pantropical). Many previously included genera will need to be moved to other tribes. Taxa previously assigned to be Old World Epidendreae are related to different groups of Old World orchids, and this study can serve as a guide for sampling strategies in future studies to resolve troublesome epidendroid orchid clades.

Phylogeny of the tribe Colletieae (Rhamnaceae) ? a sensitivity analysis of the plastid region trnL-trnF combined with morphology

The phylogenetic relationships within the tribe Colletieae (Rhamnaceae) were examined combining data from a previous morphological analysis with data from the trnL intron and trnL-F spacer. Previous studies have failed to confirm monophyly of the genus Discaria, the only genus of the tribe with an amphiantarctic distribution. The data set was analyzed using direct optimization as implemented in the computer program POY. Direct optimization searches for multiple optimal sequence alignments and is therefore well suited for analyzing DNA sequences including ambiguous alignable regions as found in the present study. Eight different costs were used for treating the indel information. Indels were treated as single events, equal to a fifth character state, or strings of gaps were treated as single events using different costs for opening a gap and extending the gap. The optimal cost set was selected by use of both character-based and topological congruence measures. Both congruence measures agreed upon a single optimal cost set. The resulting tree generally agrees with the current taxonomic treatment of the tribe Colletieae that recognizes six genera out of which three are monotypic. However, monophyly of Discaria was not supported and the results strongly suggest segregating D. nana and D. trinervis, and re-establishing the genus Ochetophila.

Molecular evolution of the trnTUGU-trnFGAA region in Bryophytes.

Structure, variability, and molecular evolution of the trnT-F region in the Bryophyta (mosses and liverworts) is analyzed based on about 200 sequences of the trnT-L spacer and trnL 5' exon, 1000 sequences of the trnL intron, and 800 sequences of the trnL 3' exon and trnL-F spacer, including comparisons of lengths, GC contents, sequence similarities, and functional elements. Mutations occurring in the trnL 5' and 3' exons, including compensatory base pair changes, and a transition in the trnL anticodon in Takakia lepidozioides, are discussed. All three non-coding regions display a mosaic structure of highly variable elements (V1 - V3 in the trnT-L spacer, V4/V5 corresponding to stem-loop regions P6/P8 in the trnL intron, and V6/V7 in the trnL-F spacer) and more conserved elements. In the trnL intron this structure is a consequence of the defined secondary structure necessary for correct splicing, whereas in both spacers conserved regions are restricted to promoter elements. At least the highly variable regions in the trnT-L spacer and stem-loop region P8 of the trnL intron seem to evolve independently in the major bryophyte lineages and are therefore not suitable for high taxonomic level phylogenetic reconstructions. In mosses, a trend of length reduction towards the more derived lineages is observed in all three non-coding regions. GC contents are mostly linked to sequence variability, with the conserved regions being more GC rich and the more variable AT rich. The lowest GC values (< 10 %) are found in the trnT-L spacer of mosses. In addition to two putative sigma (70)-type promoters in the trnT-L spacer, a third putative promoter is present in the trnL-F spacer, although trnL and trnF are assumed to be co-transcribed. Consensus sequences are provided for the -35 and -10 sequences of the major bryophyte lineages. The third promoter is part of a hairpin secondary structure, whose loop region is highly homoplastic in mosses due to an inversion occurring independently in non-related taxa, even at the intraspecific level.

Phylogenetic relationships in Nicotiana (Solanaceae) inferred from multiple plastid DNA regions

For Nicotiana, with 75 naturally occurring species (40 diploids and 35 allopolyploids), we produced 4656 bp of plastid DNA sequence for 87 accessions and various outgroups. The loci sequenced were trnL intron and trnL-F spacer, trnS-G spacer and two genes, ndhF and matK. Parsimony and Bayesian analyses yielded identical relationships for the diploids, and these are consistent with other data, producing the best-supported phylogenetic assessment currently available for the genus. For the allopolyploids, the line of maternal inheritance is traced via the plastid tree. Nicotiana and the Australian endemic tribe Anthocercideae form a sister pair. Symonanthus is sister to the rest of Anthocercideae. Nicotiana sect. Tomentosae is sister to the rest of the genus. The maternal parent of the allopolyploid species of N. sect. Polydicliae were ancestors of the same species, but the allopolyploids were produced at different times, thus making such sections paraphyletic to their extant diploid relatives. Nicotiana is likely to have evolved in southern South America east of the Andes and later dispersed to Africa, Australia, and southwestern North America.

Chloroplast Phylogeny of Asplenioid Ferns based on rbcL and trnL-F Spacer Sequences (Polypodiidae, Aspleniaceae) and its Implications for Biogeography

Abstract Molecular phylogenies have been generated to investigate relationships among species and putative segregates in Asplenium, one of the largest genera in ferns. Of the ∼700 described taxa, 71 are included in a phylogenetic analysis using the chloroplast rbcL gene and trnL-F spacer. Our results support Hymenasplenium as the sister lineage to all other asplenioid ferns, and all other putative satellite genera are nested within this asplenioid clade. Instead of the classical and well-recognized separation into Old and New World clades, asplenioid ferns reveal a separation of the deeper branches into tropical and temperate clades. Temperate clades have evolved from tropical, more-basal clades and the phylogeny indicates up to six shifts between temperate and tropical preferences in the evolution of this widespread genus. Implications for speciation processes and biogeographic aspects, including the re-colonization of temperate regions after the last glacial period, are discussed and we present a phylog...

Generic delimitations in tuberous Periplocoideae (Apocynaceae) from Africa and Madagascar.

The number of genera included in Apocynaceae subfamily Periplocoideae is a matter of debate. DNA sequences are used here as an independent dataset to clarify generic relationships and classification of the tuberous periplocoid genera and to address the question of the phylogenetic interpretation of pollinia formation in Schlechterella. Representatives of nearly all African and Malagasy genera of Periplocoideae possessing root tubers were analysed using ITS and plastid DNA sequence characters. Sequence data from non-coding molecular markers (ITS of nrDNA and the trnT-L and trnL-F spacers as well as the trnL intron of plastid DNA) give support for a broad taxonomic concept of Raphionacme including Pentagonanthus. Together with Schlechterella, which is sister to Raphionacme, all Raphionacme-like taxa form a derived monophyletic group of somewhat diverse species. Sister to the Schlechterella/Raphionacme clade is a clade comprising Stomatostemma and the not truly tuberous vine Mondia. In the combined analysis, sister to these two clades combined is a clade formed by Petopentia natalensis and Periploca. The recent inclusion of the monotypic South African Petopentia in the monotypic Malagasy endemic Ischnolepis is to be rejected. The Malagasy Camptocarpus is sister to the remainder of Periplocoideae in the ITS and combined analyses, and a Malagasy origin for the subfamily is discussed.

Delimitation of Malagasy tribe Coleeae and implications for fruit evolution in Bignoniaceae inferred from a chloroplast DNA phylogeny

Coleeae (Bignoniaceae) are a tribe almost entirely restricted to Madagascar. Coleeae have previously been placed in neotropical Crescentieae due to species with indehiscent fruits, a character otherwise unusual in Bignoniaceae. A phylogeny based on three chloroplast regions (ndhF, trnT-L spacer, trnL-F spacer) identifies a monophyletic Coleeae that is endemic to Madagascar and sur- rounding islands of the Indian Ocean (Seychelles, Comores and Mascarenes). African Kigelia is not a member of Coleeae, rather it is more closely related to a subset of African and Southeast Asian species of Tecomeae. The molecular phylogeny indicates that indehiscent fruit have arisen repeatedly in Bignoniaceae: in Coleeae, Kigelia and Crescentieae. The characteristic fleshy fruits of species of Coleeae likely arose autochthonously in Madagascar. Within Coleeae Colea and Ophiocolea are sisters, Phyllar- thron is sister to Colea + Ophiocolea ,a ndRho- docolea is sister to the rest of the tribe.

Identification of dCAPS Markers that Discriminate A and B Cytoplasms in Banana (Musa spp.)

A single nucleotide polymorphic sequence (SNP) in the trnL-F intergenic spacer region of chloroplast DNA that discriminate Musa acuminata (AA) cytoplasm from Musa balbisiana (BB) cytoplasm has been found. This mutation was initially amplified using a pair of universal primers and converted into dCAPS (derived cleaved amplified polymorphic sequence) markers. Using these markers in combination with flow cytometric analysis, ‘Pisang Klutuk’ (syn. ‘Pisang Awak’) was found to be a triploid ABB cultivar (not a wild BB accession as previously classified). A 15-bp long deletion was also found within the trnL-F spacer sequence of M. acuminata subspecies banksii. This mutation will be useful as a specific marker for the cytoplasm derived from this subspecies. These maternally inheritable chloroplast DNA mutations discovered in this study are vital for better understanding the origins of banana cytoplasm to clarify the lineage of banana cultivars and the contribution of wild progenitors to cultivated types.

A molecular phylogeny and generic rearrangement of the stapelioid Ceropegieae (Apocynaceae-Asclepiadoideae)

Representatives of nearly all genera of the taxon-rich stem-succulent stapeliads and most of the few related, leafy genera were analyzed. Sequence data from two non-coding molecular markers (ITS region of nrDNA and trnT-L and trnL-F spacers as well as the trnL intron of cpDNA) support the traditional tribal affiliation of the genera, which form a monophyletic group. This monophylum breaks into a basal Neoschumannia/Anisotoma/Riocreuxia/Sisyranthus nk;clade, from which the core Ceropegieae are derived. The four Ceropegia species included are not monophyletic, and their relationship to Brachystelma changes depending on the marker studied. The stem succulent taxa fall in a number of well supported, but unresolved clades, the most prominent being the predominantly southern African clade comprising Orbea, Stapelia and some other genera. The most derived taxa of NE Africa, Duvaliandra and White-sloanea, are basal to this southern African clade. The other clades comprise the more basal genera of stem-succulent stapeliads, including the members of the Caralluma complex. Of the 17 genera accepted by Plowes for the Caralluma complex, seven are recognized: Caralluma, Apteranthes, Australluma, Boucerosia, Caudanthera, Desmidorchis and Monolluma. New combinations are proposed in 15 cases; Caralluma adscendens var. geniculata is raised to specific rank. Anomalluma is reinstated, and Pseudolithos mccoyi is transfered to it. A broadened concept for Orbea (incl. Angolluma and Orbeopsis) is recognized, but Orbeanthus is kept separate. The monotypic Ballyanthus, recently separated from Orbea, is nested within Duvalia. Piaranthus (incl. Huerniopsis) is monophyletic. The bitypic Notechidnopsis is reduced to the type species, N. tessellata, while N. columnaris is transferred to a new genus, Richtersveldia.

MOLECULAR CONSIDERATIONS IN THE TYLOPHORINAE K. SCHUM. (APOCYNACEAE-ASCLEPIADOIDEAE)

More than 30 collections of Tylophora from all over its geographic range were analysed together with representatives of all other genera in subtribe Tylophorinae except Rhyncharrhena. Regions of the chloroplast genome (trnT-L spacer, trnL intron and trnL-F spacer) as well as the nuclear genome (internal transcribed spacer including 5.8S of nuclear ribosomal DNA) were sequenced. Both the cpDNA dataset and the rDNA dataset yield a number of stable clades, but a completely resolved and stable phylogeny is not obtained from either alone or by combining them. The small East African and Arabian genera Blyttia, Diplostigma, Goydera and Pleurostelma form a well-supported clade in both datasets. Pentatropis is always recognized as monophyletic. Vincetoxicum is not clearly separable from Tylophora, and probably covers the temperate species, while Tylophora covers those in the tropics and subtropics.

Glacial-induced altitudinal migrations in Armeria (Plumbaginaceae) inferred from patterns of chloroplast DNA haplotype sharing.

In contrast to northern European areas where large-scale migrations occurred to recolonize territories after glacial periods, species in southern regions survived and diverged without large geographical displacements. As a result of the importance of orography in much of the southern areas, such displacements must have involved populations ascending or descending mountains. The present study provides support for glacial-induced altitudinal migrations from chloroplast phylogeographic patterns in Armeria (Plumbaginaceae) in southeast Spain. One hundred and five sequences of the trnL-F spacer were obtained from seven species. Fifteen different haplotypes were recognized, their genealogy was inferred, and associations with geography were explored using nested clade analysis. Seven instances were detected in which the same haplotype is shared by two or three species within a particular massif. In all the cases, at least one of the species involved displayed different haplotypes in other areas; in most, the haplotype shared is predominant either in one of the species involved or in the massif. These patterns of haplotype sharing strongly suggest horizontal transfer between species. In one of the massifs (Sierra Nevada) the three species involved in haplotype sharing (A. splendens, A. filicaulis ssp. nevadensis, A. villosa ssp. bernisii) occur at markedly different altitudinal belts. It is argued that altitudinal migrations within the contraction-expansion model provide the best explanation for the current pattern, and that at least in one case it resulted in the formation of a new hybrid taxon, A. filicaulis ssp. nevadensis.

What is the subtribe Glossonematinae (Apocynaceae: Asclepiadoideae)? A phylogenetic study based on cpDNA spacer

Evidence from the chloroplast trnT-L spacer, trnL intron and trnL-F spacer shows the subtribe Glossonematinae of the tribe Asclepiadeae, hitherto composed of the Arabian and North African genera Glossonema, Odontanthera and Solenostemma, not to be monophyletic. While the affinities of Solenostemma cannot be determined with certainty at present, molecular, karyological and morphological evidence suggests that Glossonema and Odontanthera are closely allied to Pentarrhinum, an African genus of five species, belonging to the Cynanchinae. © 2002 The Linnean Society of London, Botanical Journal of the Linnean Society, 2002, 139, 145–158.

Phylogeographical structure revealed by chloroplast DNA variation in Japanese Beech (Fagus crenata Blume)

Intraspecific genetic variation in three non-coding chloroplast DNA (cpDNA) regions (trnT-L and trnL-F spacers, and trnL intron) of Japanese beech (Fagus crenata Blume) was investigated. This species is a major constituent of the typical cool-temperate deciduous forests in Japan. Twenty-one F. crenata populations from throughout Japan, and four F. japonica populations, a close relative of F. crenata, were examined. Seven haplotypes were distinguishable in F. crenata based on nucleotide substitutions and indels. Pairwise nucleotide diversities among haplotypes ranged from 0.0000 to 0.0042 for F. crenata, including F. japonica. The geographical distribution of cpDNA haplotypes was found to be highly structured in F. crenata. Four haplotypes predominated: haplotypes FC1 and FC4 are prevalent on the Pacific Ocean coast, haplotype FC6 is prevalent on the Japan sea coast from the San-in district to Hokkaido, whilst haplotype FC3 is restricted to northern Kyushu and the western-most part of Honshu. Two haplotypes (FC5 and FC7) are restricted to single populations and one haplotype (FC2) is a derivative of FC1. Each of these haplotypes, except FC2, are thought to be derived from different glacial refugia. Phylogenetic analysis showed that neither F. crenata nor F. japonica was monophyletic for the haplotypes, suggesting either ancestral polymorphism or ancient introgression between the lineages of these two Fagus species.

The use of dna sequencing (ITS and trnL‐F), AFLP, and fluorescent in situ hybridization to study allopolyploid Miscanthus (Poaceae)

Two clones of Miscanthus, grown under the names M. ×giganteus and M. sacchariflorus, have been used in biomass trials in Europe, but neither the identity of these clones nor their origin has been established. DNA sequencing, amplified fragment length polymorphism (AFLP), and chromosome studies confirm that M. ×giganteus is an allotriploid (2n = 3x = 57) combining genomes from M. sinensis (2n = 2x = 38) and M. sacchariflorus (2n = 38 or 76). Two alleles of the internal transcribed spacer of 18S-25S nuclear ribosomal DNA (ITS) were discovered in polymerase chain reaction products of M. ×giganteus. Cloning of these revealed that one matched M. sinensis and the other M. sacchariflorus. Plastid trnL intron and trnL-F spacer sequences showed that the maternal lineage of M. ×giganteus was M. sacchariflorus. Fluorescent in situ hybridization, FISH, was used to investigate genome organization in Miscanthus but was unable to differentiate between the different parental genomes present in M. ×giganteus, indicating that two parental genomes are still extremely similar at the repetitive DNA level. This study is an example in which rDNA sequences and AFLP fingerprints permit identification of the parental genomes in a hybrid, but FISH methods, at the repetitive DNA level (including genomic in situ hybridization, GISH), were unable to do so because their sequences remain too similar.

A Monograph of the Genus Isolepis R. Br. (Cyperaceae)

Isolepis R. Br. is a predominately southern hemisphere genus of Cyperaceae. It comprises 69 species which are recognised by having terete spikelets, bisexual flowers that lack perianth segments and the absence of a gynophore. The genus was segregated from the heterogeneous Scirpus L., and there has been much disagreement as to whether Isolepis is distinct or part of Scirpus. The phylogeny of Isolepis is reconstructed using cladistic analysis of morphological and DNA (rbcL, trnL intron and trnL-F spacer) sequence data. Isolepis is sister to Ficinia, and together these form a clade (with Scirpoides) sister to Cyperus sensu lato in subfamily Cyperoideae. The genus Isolepis, as currently delimited, is not monophyletic as some species (e.g. I. marginata) are grouped with the Ficinia clade whereas another species (I. humillima) is closer to Cyperus. The removal of the these species from the genus would make Isolepis monophyletic. Three infrageneric clades observed in Isolepis are recognised as subgenera, namely Isolepis (e.g. L sotacea), Fluitantes (e.g. I. fluitans), and Micranthae (e.g. I. hystrix). In addition, subgen. Isolepis has three well supported subclades, recognised here as sections (i.e. sect. Isolepis, Cernuae and Proliferae). The I. fluitans clade has been considered by some authors as a separate genus, Eleogiton Link, but segregating the clades in Isolepis into genera creates groups with obscure limits and minor delimiting characters. The taxonomy of the genus is revised to determine species limits and nomenclature. A full taxonomic account is presented. Two new species and a new variety are described.

Phylogeny and biogeography of southern hemisphere high-mountain Cardamine species (Brassicaceae)

The biogeography and phylogenetic relationships of Southern Hemisphere Cardamine L. species were analysed using nuclear rDNA ITS and cpDNA (trnL intron, trnL-F spacer) sequences. The analyses indicate that the montane species from Australia and New Zealand (C. corymbosa Hook.f., C. lilacina Hook. and C. debilis Banks ex DC.) are closely related to the South American C. glacialis (Forster) DC. Low sequence divergence between C. glacialis and the Australian and New Zealand species suggests relatively recent (less than 500 000 years ago) long-distance dispersal from South America to Australasia, or vice versa. The relationship of the New Guinean species, C. keysseri O.E.Schulz and C. africana L., to the Australian species remained unresolved. Accessions of the high-mountain, pan-continental species C. africana from Africa, South America and New Guinea differed widely in their positions on both the ITS tree and the cpDNA tree, suggesting a polyphyletic origin. The East African high-mountain species C. obliqua Hochst. grouped with European species on the cpDNA tree. The African species, C. trichocarpa Hochst., formed a sister group to all the other Cardamine species analysed.

Molecular Phylogenetics and Morphological Evolution in Cunonieae (Cunoniaceae)

The Cunonieae are the largest tribe in the flowering plant family Cunoniaceae and include the widespread genus Weinmannia. This study aims to understand phylogenetic relationships within Cunonieae by using DNA sequences in a parsimony-cladistic analysis. Sequenced loci included the internal transcribed spacers (ITS-1 and ITS-2) of nuclear ribosomal DNA, and the trnL intron and trnL-F spacer of chloroplast DNA. Primer and taxon-specific amplification of non-orthologous ITS-2 copies made it necessary to exclude the ITS-2 data, but otherwise the nuclear and chloroplast data sets were congruent. The results place Vesselowskya as the sister genus to other Cunonieae and support the monophyly of Pancheria, Cunonia, and all five sections of Weinmannia, but do not indicate how these groups are related. The monophyly of Weinmannia sect. Weinmannia is upheld, with W. trichosperma from temperate forests of South America and W. tinctoria from the Mascarene Islands placed basal to a large clade of tropical American species. Although morphological data maintain the monophyly of Weinmannia, this is neither verified nor statistically refuted by the molecular data. Likewise, Cunonia, with one isolated South African species, has only weak molecular support hut clear morphological synapomorphies. Lack of support for relationships among major clades within Cunonieae makes it difficult to suggest patterns of morphological evolution. However, a well-supported phylogenetic hypothesis within Weinmannia sect. Leiospermum is used to discuss heterotopy in inflorescence architecture. Uniquely derived features of the inflorescence are found in the New Caledonian species Weinmannia dichotomy and in the New Zealand species W silvicola and W. racemosa. These heterotopic changes involve alternate patterns in the fate of terminal meristems and the arrangement of metamers bearing racemes. In an appendix the correct orthographies and original publications of all five sections of Weinmannia are provided; types are also designated for Weinmannia sections Inspersae and Spicatae in order to validate them.

Inclusion of Tenaris and Macropetalum in Brachystelma (Apocynaceae-Asclepiadoideae-Ceropegieae) inferred from non-coding nuclear and chloroplast DNA sequences

The inclusion of Tenaris and Macropetalum in Brachystelma as proposed by Peckover in 1996 and contested by Victor and Nicholas in 1998 is supported by molecular studies. Parsimony analysis of sequence data from two non-coding molecular markers (ITS region of nrDNA and trnT-L and trnL-F spacers as well as the trnL intron of cpDNA) suggests a well-supported Brachystelma s.l. clade (including Tenaris and Macropetalum) with little internal resolution. The Brachystelma s.l. clade occupies a sistergroup position to the Ceropegia/stapeliad clade, and both clades together are sister to an Anisotoma/Sisyranthus/Neoschumannia clade.

Subtribe Astephaninae (Apocynaceae-Asclepiadoideae) Reconsidered: New Evidence Based on cpDNA Spacers

The circumscription of the subtribe Astephaninae has a complex and convoluted history due in part to a scarcity of readily observed distinctive morphological characters. In this study the subtribe Astephaninae, as hitherto defined by morphological characters, is reexamined using sequences of the tmT-L and trnL-F spacer, as well as the trnL intron for 12 of its 15 genera. Eustegia is found to occupy an isolated basal position in the tribe Asclepiadeae, and Schizostephanus is transferred to the Metastelminae. The remaining 10 genera fall into two only distantly related clades of 3 and 7 genera, respectively. The Astephaninae s. str. comprise only 3 South African genera, Astephanus s. str., Microloma, and Oncinema. The other 7 genera form a well-supported clade, the subtribe Tylophorinae. Both groups comprise only Old World genera. All New World taxa studied, even those that have never been formally excluded from Astephanus, are found in a distinct, well-supported New World Metastelminae clade. Based on the results presented here one of the key characters of the asclepiads-the corona-has been lost independently at least twice: once in the south African Astephaninae, and once in the New World Metastelminae. This once again underscores the extreme lability of this morphologically complex organ, as well as the difficulties in assessing homology in the asclepiads. A corollary classification of the Asclepiadeae is provided as an Appendix.

Phylogenetic Relationships within Apocynaceae s.l. Based on trnL Intron and trnL-F Spacer Sequences and Propagule Characters

Relationships within Apocynaceae s.l. (Apocynaceae s. str., Periplocaceae, and Asclepiadaceae) were investigated by maximum parsimony analysis of morphological and molecular sequence data. Sequences of the plastid trnL intron and trnL-F spacer for 152 accessions for representatives of all major tribes were included in this study; 96% of these sequences represent new data. Two outgroups were selected from the closely related Loganiaceae. The total evidence matrix incorporated trnL intron and trnL-F spacer sequences, insertion/deletion information, and propagule characters. The phylogenetic hypothesis derived from this data set was used to evaluate the most current classification systems and was also used to investigate trends in seed dispersal. Apocynaceae s.l. are a strongly defined monophyletic group, a finding that should be reflected in taxonomic treatments. The recognition of three of the five subfamilies proposed by Endress and Bruyns in 2000 is supported by the monophyletic Periplocoideae, Secamonoideae, and Asclepiadoideae, whereas the paraphyletic Rauvolfioideae and Apocynoideae are not supported. The precise position of the Periplocoideae, however, remains unclear. Traditional tribal delimitations were less congruent with our total evidence phylogeny. The evolution of seed comas and enhanced long-distance dispersal within the Apocynaceae s.l. probably contributed to accelerated cladogenesis, ultimately giving rise to the majority of the extant genera within the family. Phylogeographic analysis of our data provides some evidence for a Gondwanan origin of the family.