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Mark W Chase - One of the best experts on this subject based on the ideXlab platform.
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generic phylogeny and character evolution in urticeae urticaceae inferred from nuclear and Plastid DNA regions
Taxon, 2015Co-Authors: Mark W Chase, Tao Deng, Daigui ZhangAbstract:This study examines phylogenetic relationships among the 12 genera of Urticeae (Urticaceae) and investigates the pattern of morphological evolution based on analysis of nuclear ribosomal internal transcribed spacer (nrITS) and two Plastid DNA regions (rbcL exon, trnL-F spacer). Sequence data were analyzed using maximum parsimony and Bayesian inference, and selected morphological traits were mapped onto the molecular tree. The molecular results strongly supported monophyly of Urticeae, excluding Gyrotaenia, which is related to Elatostemateae. All genera were monophyletic except for Urtica, Laportea, and Urera. Two Hesperocnide species are nested within Urtica. Laportea and Urera are divided into three groups with a strong geographical signal. The inferred phylogeny indicates five well-supported clades in Urticeae: clade A including Urtica (with Hesperocnide), Zhengyia, Laportea I, and Nanocnide; clade B comprising Dendrocnide and Discocnide; clade C including only Girardinia; clade D including Laportea II; and clade E including Obetia, Urera I, II, III, and Poikilospermum. Although it is difficult to identify morphological synapomorphies for these well-defined clades within Urticeae, character analysis shows that the herbaceous habit and alternate leaves are the ancestral states in the tribe. The presence of stinging hairs is the derived status in Urticeae, and it might have been a key innovation triggering species diversification in the tribe.
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molecular phylogenetics of the juno irises iris subgenus scorpiris iridaceae based on six Plastid markers
Botanical Journal of the Linnean Society, 2011Co-Authors: Nursel Ikinci, James J. Clarkson, Tony Hall, Dolores M Lledo, Nico Tillie, Arnis Seisums, Takeshi Saito, Madeline M Harley, Mark W ChaseAbstract:Relationships among the roughly 55 species of Iris subgenus Scorpiris have been studied. A matrix of six Plastid DNA regions (matK, rpl14-rps8 spacer, infA-rpl36 spacer, trnE-trnT spacer, trnL intron and trnL-F spacer) was produced from 57 accessions (52 taxa) and analysed with both parsimony and Bayesian methods. Five major clades are identified, of which four have strong geographical correlations, whereas the fifth corresponds to Iris section Physocaulon. In our results, several species are placed with species not previously considered to be related, although, in some cases, there are morphological characters that suggest that these newly indicated relationships are reasonable. For some of the other oddly grouped species, we can only assume that remarkable parallelisms in morphology have occurred or hybridization is involved. Presently, with Plastid DNA as our only comprehensive data resource, we are not able to evaluate more thoroughly these more puzzling associations of species. © 2011 The Linnean Society of London, Botanical Journal of the Linnean Society, 2011, 167, 281–300.
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molecular phylogenetics of hypoxidaceae evidence from Plastid DNA data and inferences on morphology and biogeography
Molecular Phylogenetics and Evolution, 2011Co-Authors: Alexander Kocyan, Mark W Chase, John V Freudenstein, Deirdre A Snijman, Felix Forest, Dion S Devey, Justyna Wilandszymanska, Paula J RudallAbstract:Abstract Phylogenetic relationships of the monocot family Hypoxidaceae (Asparagales), which occurs mainly in the Southern Hemisphere, were reconstructed using four Plastid DNA regions ( rbcL , trnL intron, trnL-F intergenic spacer, and trnS-G intergenic spacer) for 56 ingroup taxa including all currently accepted genera and seven species of the closely related families Asteliaceae, Blandfordiaceae, and Lanariaceae. Data were analyzed by applying parsimony, maximum likelihood and Bayesian methods. The intergenic spacer trnS-G – only rarely used in monocot research – contributed a substantial number of potentially parsimony informative characters. Hypoxidaceae consist of three well-supported major clades, but their interrelationships remain unresolved. Our data indicate that in the Pauridia clade one long-distance dispersal event occurred from southern Africa to Australia. Long-distance dispersal scenarios may also be likely for the current distribution of Hypoxis , which occurs on four continents. In the Curculigo clade, the present distribution of Curculigo s.s. on four continents could support a Gondwanan origin, but the level of divergence is too low for this hypothesis to be likely. The main clades correspond well with some floral characters, habit and palynological data, whereas chromosomal data exhibit plasticity and probably result from polyploidization and subsequent dysploidy and/or aneuploidy. Evolutionary flexibility is also suggested by the number of reported pollination syndromes: melittophily, myophily, sapromyophily, and cantharophily. Based on our phylogenetic results, we suggest cautious nomenclatural reorganization to generate monophyly at the generic level.
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Reticulate evolution in diploid and tetraploid species of Polystachya (Orchidaceae) as shown by Plastid DNA sequences and low-copy nuclear genes.
Annals of Botany, 2010Co-Authors: Anton Russell, Rosabelle Samuel, Verena Klejna, Michael H. J. Barfuss, Barbara Rupp, Mark W ChaseAbstract:Background and Aims Here evidence for reticulation in the pantropical orchid genus Polystachya is presented, using gene trees from five nuclear and Plastid DNA data sets, first among only diploid samples (homoploid hybridization) and then with the inclusion of cloned tetraploid sequences (allopolyploids). Two groups of tetraploids are compared with respect to their origins and phylogenetic relationships.
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phylogenetics and cytology of a pantropical orchid genus polystachya polystachyinae vandeae orchidaceae evidence from Plastid DNA sequence data
Taxon, 2010Co-Authors: Anton Russell, Rosabelle Samuel, Michael H. J. Barfuss, Barbara Rupp, Marko Safran, Visnja Besendorfer, Mark W ChaseAbstract:The pantropical orchid genus Polystachya is the subject of ongoing taxonomic work. We inferred phylogenetic relation¬ships in the genus using 5.3 kb of Plastid DNA, for 83 out of ca. 240 species and 12 out of 15 sections, as well as five outgroup species. We also collected ploidy data using chromosome counts and genome size estimates. Bayesian and parsimony trees were congruent with each other and well resolved. Polystachya appears monophyletic based on current sampling, provided that the name P. neobenthamia is used instead of Neobenthamia gracilis for that species. The current sectional classification does not define monophyletic groups, but the present study can be used as the basis for a future sectional classification. Areas postulated as Pleistocene refugia for wet tropical forests in Africa also form centres of diversity for the genus. Biogeographical analyses using DIVA and Lagrange show an early radiation in eastern Africa, followed by separate radiations in eastern and western Africa. Subsequent dispersal from western to eastern Africa has occurred at a much higher rate than from east to west. Dispersal to the Neotropics occurred more than once, and one lineage has spread recently and rapidly throughout the tropics. Polyploidy has occurred several times during the diversification of the genus, most notably in association with the recent pantropical dispersal.
Mikael Hedrén - One of the best experts on this subject based on the ideXlab platform.
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phylogeography of the european rock rose helianthemum nummularium cistaceae incongruent patterns of differentiation in Plastid DNA and morphology
Botanical Journal of the Linnean Society, 2014Co-Authors: Eman Soubani, Mikael Hedrén, Bjorn WidenAbstract:Helianthemum nummularium is a morphologically variable species that has been subdivided into several subspecies based on indumentum characters. We investigated four of these subspecies for variation in Plastid DNA and leaf and petal shape in Europe. Three size-variable mononucleotide repeat regions were amplified by means of species-specific primers and 18 combined haplotypes were identified. The highest haplotype diversity was found in the Alps and the surrounding lowland areas, whereas marginal areas such as northern Europe and the south-eastern Balkans had a lower diversity. Most of the common haplotypes were shared between subspecies and showed a geographical structuring across the range of the species, whereas geographically restricted haplotypes were found elsewhere (e.g. in the Baltic area). Leaf and petal shape descriptors could not differentiate between subspecies. The role of hybridization and introgression between post-glacial migration lineages is discussed. As an alternative hypothesis to introgression between ancient taxa, we suggest that the poor correspondence between Plastid haplotype distribution and subspecies circumscription could be a result of multiple origins of similar morphs (grouped into taxonomic subspecies) in different parts of the distribution range of the complex. (c) 2014 The Linnean Society of London, Botanical Journal of the Linnean Society, 2014, 176, 311-331. (Less)
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polyploid evolution and Plastid DNA variation in the dactylorhiza incarnata maculata complex orchidaceae in scandinavia
Molecular Ecology, 2008Co-Authors: Mikael Hedrén, Sofie Nordström, David StåhlbergAbstract:The Dactylorhiza incarnata/maculata complex (Orchidaceae) was used as a model system to understand genetic differentiation processes in a naturally occurring polyploid complex with much of ongoing diversification and wide distribution in recently glaciated areas in northern Europe. Data were obtained for 12 hypervariable regions in the Plastid DNA genome. A total of 166 haplotypes were found in a sample of 1099 plants. Allopolyploid taxa have inherited their Plastid genomes from D. maculata s.l. Overall haplotype diversity of the combined group of allopolyploid taxa was comparable to that of maternal D. maculata s.l., but populations of allopolyploids were also more strongly differentiated from each other and contained lower numbers of haplotypes than populations of D. maculata s.l. In addition to haplotypes found in extant D. maculata s.l., the allopolyploids also contained several distinct and widespread haplotypes that were not found in any of the parental lineages. Some of these haplotypes were shared between widespread allopolyploids. Divergent allopolyploids with small distributions did not seem to originate from local polyploidization events, but rather as segregates of already existing allopolyploids. Genetic diversification of allopolyploid Dactylorhiza is the result of repeated polyploid formation, secondary hybridization and introgression between already existing polyploids and extant representatives of parental lineages, hybridization between independently derived polyploid lineages, and phyletic diversification in the group of allopolyploids. Although some polyploid taxa must have evolved after the last glaciation, genetic material from the parental lineages has been transferred continuously for longer periods of time. This combination of processes may explain the taxonomic complexity encountered in Dactylorhiza and other polyploid complexes distributed in previously glaciated parts of Europe.
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systematics and phylogeography of the dactylorhiza maculata complex orchidaceae in scandinavia insights from cytological morphological and molecular data
Plant Systematics and Evolution, 2008Co-Authors: David Ståhlberg, Mikael HedrénAbstract:Flow cytometry, morphometry and molecular markers (Plastid DNA and internal transcribed spacers (ITS) of nuclear ribosomal DNA) were used to determine taxonomic and phylogeographic patterns in Dactylorhiza maculata s.l. from Scandinavia. A total of 238 individuals from 27 populations from throughout all of Scandinavia, including the adjacent Kola Peninsula of Russia, were analyzed. Diploid D. maculata ssp. fuchsii and autotetra- ploid D. maculata ssp. maculata are morphologically differentiated. Fragment size variants from 10 Plastid DNA loci (seven microsatellite loci and three loci with indel variation) were combined to give 43 haplotypes. Three major groups of haplotypes were found. Group I haplo- types were prevalent in the north and the northeast, whereas Group II haplotypes were prevalent in the south and the southwest. Group III was represented by only a single haplotype and appeared to be the result of intro- gression from D. incarnata s.l. Group I and Group II haplotypes did not correspond with cytologically and morphologically defined D. maculata ssp. fuchsii or D. maculata ssp. maculata. Past introgressive gene flow rather than recent hybridization is envisaged. Intermediate Group I haplotypes between Group II and the rest of Group I were detected in a zone of contact in central Sweden, which may suggest Plastid DNA recombination. The six ITS alleles scored showed strong positive correlation with taxonomy. All data sets obtained for ssp. maculata were significantly correlated with geography. Three different autotetraploid lineages are hypothesized. One lineage may represent postglacial immigration from the south and the other two lineages may represent eastern immigration routes. Morphology and ITS data suggested that subarctic populations of ssp. maculata should be recognized as var. kolaensis.
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patterns of polyploid evolution in greek marsh orchids dactylorhiza orchidaceae as revealed by allozymes aflps and Plastid DNA data
American Journal of Botany, 2007Co-Authors: Mikael Hedrén, Henrik Aerenlund Pedersen, Sofie Nordström, Helena Persson A Hovmalm, Sven HanssonAbstract:Polyploidy is common in higher plants, and speciation in polyploid complexes is usually the result of reticulate evolution. We examined variation in nuclear AFLP fingerprints, nuclear isozymes, and hypervariable Plastid DNA loci to describe speciation patterns and species relationships in the Dactylorhiza incarnata/maculata polyploid complex (marsh orchids; Orchidaceae) in Greece. Several endemic taxa with restricted distribution have been described from this area, and to propose meaningful conservation priorities, detailed relationships need to be known. We identified four independently derived allopolyploid lineages, which is a pattern poorly correlated with prevailing taxonomy. Three lineages were composed of populations restricted to small areas and may be of recent origins from extant parental lineages. One lineage with wide distribution in northern Greece was characterized by several unique Plastid haplotypes that were phylogenetically related and evidently older. The D. incarnata/maculata polyploid complex in Greece has high levels of genetic diversity at the polyploid level. This diversity has accumulated over a long time and may include genetic variants originating from now extinct parental populations. Our data also indicate that the Balkans may have constituted an important refuge from which northern European Dactylorhiza were recruited after the Weichselian ice age.
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Plastid DNA variation in the dactylorhiza incarnata maculata polyploid complex and the origin of allotetraploid d sphagnicola orchidaceae
Molecular Ecology, 2003Co-Authors: Mikael HedrénAbstract:To obtain further information on the polyploid dynamics of the the Dactylorhiza incarnata/maculata polyploid complex and the origin of the allotetraploid D. sphagnicola ( Orchidaceae), Plastid DNA variation was studied in 400 plants from from Sweden and elsewhere in Europe and Asia Minor by means of polymerase chain reaction-restriction fragment length polymorphisms (PCR-RFLPs) and sequencing. Allotetraploid taxa in Europe are known have evolved by multiple independent polyploidization events following hybridization between the same set of two distinct ancestral lineages. Most allotetraploids have inherited the Plastid genome from parents similar to D. maculata sensu lato, which includes, e. g. the diploid D. fuchsii and the autotetraploid D. maculata sensu stricto. D. sphagnicola carries a separate Plastid haplotype different from the one found in other allotetraploid taxa, which is in agreement with an independent origin from the parental lineages. Some of the remaining allotetraploids have local distributions and appear to be of postglacial origin, whereas still other allotetraploids may be of higher age, carrying Plastid haplotypes that have not been encountered in present day representatives of the parental lineages. Introgression and hybridization between diploids and allotetraploids, and between different independently derived allotetraploids may further have contributed to genetic diversity at the tetraploid level. Overall, the Dactylorhiza polyploid complex illustrates how taxon diversity and genetic diversity may be replenished rapidly in a recently glaciated area.
Rosabelle Samuel - One of the best experts on this subject based on the ideXlab platform.
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Sequencing of whole Plastid genomes and nuclear ribosomal DNA of Diospyros species (Ebenaceae) endemic to New Caledonia: many species, little divergence
Annals of Botany, 2016Co-Authors: Barbara Turner, Jérôme Munzinger, Ovidiu Paun, Mark Chase, Rosabelle SamuelAbstract:Background and Aims: Some plant groups, especially on islands, have been shaped by strong ancestral bottlenecks and rapid, recent radiation of phenotypic characters. Single molecular markers are often not informative enough for phylogenetic reconstruction in such plant groups. Whole Plastid genomes and nuclear ribosomal DNA (nrDNA) are viewed by many researchers as sources of information for phylogenetic reconstruction of groups in which expected levels of divergence in standard markers are low. Here we evaluate the usefulness of these data types to resolve phylogenetic relationships among closely related Diospyros species. Methods: Twenty-two closely related Diospyros species from New Caledonia were investigated using whole Plastid genomes and nrDNA data from low-coverage next-generation sequencing (NGS). Phylogenetic trees were inferred using maximum parsimony, maximum likelihood and Bayesian inference on separate Plastid and nrDNA and combined matrices. Key Results: The Plastid and nrDNA sequences were, singly and together, unable to provide well supported phylogenetic relationships among the closely related New Caledonian Diospyros species. In the nrDNA, a 6-fold greater percentage of parsimony-informative characters compared with Plastid DNA was found, but the total number of informative sites was greater for the much larger Plastid DNA genomes. Combining the Plastid and nuclear data improved resolution. Plastid results showed a trend towards geographical clustering of accessions rather than following taxonomic species. Conclusions: In plant groups in which multiple Plastid markers are not sufficiently informative, an investigation at the level of the entire Plastid genome may also not be sufficient for detailed phylogenetic reconstruction. Sequencing of complete Plastid genomes and nrDNA repeats seems to clarify some relationships among the New Caledonian Diospyros species, but the higher percentage of parsimony-informative characters in nrDNA compared with Plastid DNA did not help to resolve the phylogenetic tree because the total number of variable sites was much lower than in the entire Plastid genome. The geographical clustering of the individuals against a background of overall low sequence divergence could indicate transfer of Plastid genomes due to hybridization and introgression following secondary contact.
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Reticulate evolution in diploid and tetraploid species of Polystachya (Orchidaceae) as shown by Plastid DNA sequences and low-copy nuclear genes.
Annals of Botany, 2010Co-Authors: Anton Russell, Rosabelle Samuel, Verena Klejna, Michael H. J. Barfuss, Barbara Rupp, Mark W ChaseAbstract:Background and Aims Here evidence for reticulation in the pantropical orchid genus Polystachya is presented, using gene trees from five nuclear and Plastid DNA data sets, first among only diploid samples (homoploid hybridization) and then with the inclusion of cloned tetraploid sequences (allopolyploids). Two groups of tetraploids are compared with respect to their origins and phylogenetic relationships.
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phylogenetics and cytology of a pantropical orchid genus polystachya polystachyinae vandeae orchidaceae evidence from Plastid DNA sequence data
Taxon, 2010Co-Authors: Anton Russell, Rosabelle Samuel, Michael H. J. Barfuss, Barbara Rupp, Marko Safran, Visnja Besendorfer, Mark W ChaseAbstract:The pantropical orchid genus Polystachya is the subject of ongoing taxonomic work. We inferred phylogenetic relation¬ships in the genus using 5.3 kb of Plastid DNA, for 83 out of ca. 240 species and 12 out of 15 sections, as well as five outgroup species. We also collected ploidy data using chromosome counts and genome size estimates. Bayesian and parsimony trees were congruent with each other and well resolved. Polystachya appears monophyletic based on current sampling, provided that the name P. neobenthamia is used instead of Neobenthamia gracilis for that species. The current sectional classification does not define monophyletic groups, but the present study can be used as the basis for a future sectional classification. Areas postulated as Pleistocene refugia for wet tropical forests in Africa also form centres of diversity for the genus. Biogeographical analyses using DIVA and Lagrange show an early radiation in eastern Africa, followed by separate radiations in eastern and western Africa. Subsequent dispersal from western to eastern Africa has occurred at a much higher rate than from east to west. Dispersal to the Neotropics occurred more than once, and one lineage has spread recently and rapidly throughout the tropics. Polyploidy has occurred several times during the diversification of the genus, most notably in association with the recent pantropical dispersal.
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generic delimitation and relationships in ebenaceae sensu lato evidence from six Plastid DNA regions
American Journal of Botany, 2006Co-Authors: Sutee Duangjai, Jérôme Munzinger, Rosabelle Samuel, Bruno Wallnöfer, Mark W ChaseAbstract:Phylogenetic relationships of the pantropical family Ebenaceae s.l. were investigated using Plastid DNA sequence data from six regions: atpB, matK, ndhF, trnK intron, trnL intron, and trnL-trnF spacer. Sampling included representatives of all currently recognized genera of Ebenaceae, Diospyros, Euclea, and Lissocarpa, and nearly all taxa that were previously recognized at the generic level, e.g., Cargillia, Gunisanthus, Maba, Macreightia, Royena, and Tetraclis. Our results strongly support monophyly of Ebenaceae s.l. and demonstrate that the previous infrafamilar classifications of the family do not circumscribe monophyletic groups. A new infrafamilial classification based on a phylogenetic approach is proposed here and consists of two subfamilies, Lissocarpoideae and Ebenoideae, and four genera, Lissocarpa, Euclea, Royena, and Diospyros. Relationships and potential synapomorphic characters are discussed and summarized. This study supports a western Gondwanan origin of family and indicates that both vicariant and long-distance dispersal events played an important role in attaining current distributions.
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molecular phylogenetics of meliaceae sapindales based on nuclear and Plastid DNA sequences
American Journal of Botany, 2003Co-Authors: Alexandra N. Muellner, Rosabelle Samuel, Sheila A Johnson, Martin Cheek, Mark W ChaseAbstract:Phylogenetic analyses of Meliaceae, including representatives of all four currently recognized subfamilies and all but two tribes (32 genera and 35 species, respectively), were carried out using DNA sequence data from three regions: Plastid genes rbcL, matK (partial), and nuclear 26S rDNA (partial). Individual and combined phylogenetic analyses were performed for the rbcL, matK, and 26S rDNA data sets. Although the percentage of informative characters is highest in the segment of matK sequenced, rbcL provides the greatest number of informative characters of the three regions, resulting in the best resolved trees. Results of parsimony analyses support the recognition of only two subfamilies (Melioideae and Swietenioideae), which are sister groups. Melieae are the only tribe recognized previously that are strongly supported as monophyletic. The members of the two small monogeneric subfamilies, Quivisianthe and Capuronianthus, fall within Melioideae and Swietenioideae, respectively, supporting their taxonomic inclusion in these groups. Furthermore, the data indicate a close relationship between Aglaieae and Guareeae and a possible monophyletic origin of Cedreleae of Swietenioideae. For Trichilieae (Melioideae) and Swietenieae (Swietenioideae) lack of monophyly is indicated.
Peter Goldblatt - One of the best experts on this subject based on the ideXlab platform.
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a molecular phylogeny and a revised classification of ornithogaloideae hyacinthaceae based on an analysis of four Plastid DNA regions
Taxon, 2009Co-Authors: J C Manning, Michael F. Fay, Felix Forest, Dion S Devey, Peter GoldblattAbstract:The most recent classification of Hyacinthaceae subsumes all members of Ornithogaloideae into the single large genus Ornithogalum comprising 250―300 spp. A combined molecular phylogenetic analysis of matK, trnL intron, trnL-F spacer and rbcL Plastid DNA sequence data was carried out to assess possible alternative treatments. The study includes 70 taxa, representing all segregate genera that have been recognised in the subfamily and over 20% of the species. The resulting phylogeny identifies three, well-supported primary clades. Clade A comprises a grade constituting the majority of species of Stellarioides plus the Madagascan Igidia, in which is nested a strongly supported clade comprising Albuca and Coilonox; Clade B comprises Dipcadi sister to Pseudogaltonia; and Clade C comprises Eliokarmos, Cathissa, Galtonia, Honorius, Loncomelos, Melomphis, Neopatersonia, Ornithogalum, Zahariadia and two species of Stellarioides. The Madagascan Avonsera convallarioides is weakly supported as sister to the rest of clade C. Several of the segregate genera of Ornithogalum are shown not to be monophyletic although many of the lineages identified by the analysis correspond to lower level taxa that have been recognised in the group. Each of the three primary clades has morphological integrity and could be recognised taxonomically, either at the level of tribe or genus. Within these clades, however, many lineages are poorly defined morphologically and thus their recognition at the level of genus is problematical. Alternative taxonomic treatments are assessed but considerations of nomenclatural stability and taxonomic utility predicate that these lineages are best recognised at infrageneric level. We accordingly prefer to define the genera more broadly. Clade A is recognised as genus Albuca, clade B as comprising the genera Dipcadi and Pseudogaltonia, and clade C as the genus Ornithogalum. Monophyletic, morphologically diagnosable lineages within the genera Albuca and Ornithogalum are treated as subgenera and sections. A revised classification is presented, with necessary new combinations and complete listings of all currently accepted sub-Saharan species.
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iridaceae out of australasia phylogeny biogeography and divergence time based on Plastid DNA sequences
Systematic Botany, 2008Co-Authors: Peter Goldblatt, J C Manning, Jonathan T Davies, Michelle Van Der Bank, Aaron Rodriguez, Martyn P Powell, Vincent SavolainenAbstract:Abstract The current infrafamilial taxonomy of the Iridaceae recognizes four subfamilies; Isophysidoideae (1: 1); Nivenioideae (6: ca. 92), Iridoideae (29: 890), and Crocoideae (29: 1032). Phylogenetic analyses of sequences of five Plastid DNA regions, rbcL, rps4, trnL–F, matK, and rps16, confirm most aspects of this classification and the evolutionary patterns that they imply, importantly the sisiter relationship of Isophysidoideae to the remainder of the family and the monophyly of Iridoideae. Subfamily Nivenioideae is, however, paraphyletic; Crocoideae is consistently found nested within it, sister to the core Nivenioideae, the woody Klattia, Nivenia, and Witsenia. This clade is sister to Aristea, which in turn is sister to the Madagascan Geosiris, and then to the Australasian Patersonia. We treat Aristea, Geosiris, and Patersonia as separate subfamilies, Aristeoideae and the new Geosiridaceae and Patersonioideae, rendering Nivenioideae and Crocoideae monophyletic. The alternative, uniting a widely cir...
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phylogeny of iridaceae subfamily crocoideae based on a combined multigene Plastid DNA analysis
Aliso, 2006Co-Authors: Peter Goldblatt, J C Manning, Jonathan T Davies, Michelle Van Der Bank, Vincent SavolainenAbstract:The phylogeny of Crocoideae, the largest of four subfamilies currently recognized in Iridaceae, has eluded resolution until sequences of two more Plastid DNA regions were added here to a previously published matrix containing sequences from four DNA Plastid regions. Sister to the core Nivenioideae, the woody Klattia, Nivenia, and Witsenia, Crocoideae are a climax group in Iridaceae, comprising some 995 species, slightly more than half of the total in the family. Synapomorphies of Crocoideae include pollen exine perforate, pollen aperture operculate, ovule campylotropous (or hypotropous), root xylem vessels with simple perforations, cormous rootstock, inflorescence a spike, and plants deciduous. The six DNA region analysis here that includes examples of 27 of the 28 genera of the subfamily shows the southern African Tritoniopsis sister to the remaining genera, which resolve into four well-supported clusters (bootstrap support >85%). Each of these major clades is treated as a tribe, the synapomorphies of which are discussed in light of the molecular phylogenetic analyses. Original embryological and seed developmental studies largely support the tribal classification. Tritoniopsideae alone has the inner floral bracts not forked apically, and a hypotropous ovule, while this tribe and Watsonieae have axillary corm development. The remaining three tribes have apical corm development, and together with Watsonieae have a campylotropous ovule, and the inner layer of the inner integument crushed at maturity.
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radiation in the cape flora and the phylogeny of peacock irises moraea iridaceae based on four Plastid DNA regions
Molecular Phylogenetics and Evolution, 2002Co-Authors: Peter Goldblatt, Gail Reeves, J C Manning, Vincent Savolainen, Martyn P Powell, Obie Porteous, Ivan Sostaric, Timothy G Barraclough, Mark W ChaseAbstract:Abstract Phylogenetic analyses of four Plastid DNA regions, the rbcL exon, trnL intron, trnL–trnF intergenic spacer, and rps16 intron from each of 73 species in the African genus Moraea (Iridaceae: Irideae) including accessions of all major species clusters in the genus, show Moraea to be paraphyletic when Barnardiella, Galaxia, Hexaglottis, Homeria (all southern African), and Gynandriris (Eurasian as well) were recognized as separate genera. There are several small, isolated species clusters at the basal nodes of the tree that are all restricted to the winter-rainfall zone of southern Africa (the Greater Cape floral kingdom) and a few, highly derived, large species groups that have radiated extensively within the winter-rainfall zone. Mapping of floral traits shows that an Iris-type flower is ancestral in Moraea. Floral changes are associated with shifts in pollination systems, either from passive pollen deposition on long-tongued bees foraging for nectar to active pollen collection by female bees foraging for pollen, fly, or hopliine scarab beetle pollination. Dating the nodes of the phylogenetic tree using non-parametric rate smoothing with a calibration point derived from broad dating of the angiosperms indicates that the divergence between Moraea and its sister genus Ferraria occurred about 25 mya in the early Miocene. The early radiation of Moraea took place against a background of aridification and the spread of open habitats, such as desert, shrubland, and fynbos.
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molecular systematics of iridaceae evidence from four Plastid DNA regions
American Journal of Botany, 2001Co-Authors: Gail Reeves, Paula J Rudall, Mark W Chase, Peter Goldblatt, Bernard Lejeune, Tatiana T SouzachiesAbstract:Iridaceae are one of the largest families of Lilianae and probably also among the best studied of monocotyledons. To further evaluate generic, tribal, and subfamilial relationships we have produced four Plastid DNA data sets for 57 genera of Iridaceae plus outgroups: rps4, rbcL (both protein-coding genes), the trnL intron, and the trnL-F intergenic spacer. All four matrices produce similar although not identical trees, and we thus analyzed them in a combined analysis, which produced a highly resolved and well-supported topology, in spite of the fact that the partition homogeneity test indicated strong incongruence. In each of the individual trees, some genera or groups of genera are misplaced relative to morphological cladistic studies, but the combined analysis produced a pattern much more similar to these previous ideas of relationships. In the combined tree, all subfamilies were resolved as monophyletic, except Nivenioideae that formed a grade in which Ixioideae were embedded. Achlorophyllous Geosiris (sometimes referred to Geosiridaceae or Burmanniaceae) fell within the nivenioid grade. Most of the tribes were monophyletic, and Isophysis (Tasmanian) was sister to the rest of the family; Diplarrhena (Australian) fell in a well-supported position as sister to Irideae/Sisyrinchieae/Tigridieae/Mariceae (i.e., Iridoideae); Bobartia of Sisyrinchieae is supported as a member of Irideae. The paraphyly of Nivenioideae is suspicious due to extremely high levels of sequence divergence, and when they were constrained to be monophyletic the resulting trees were only slightly less parsimonious (,1.0%). However, this subfamily also lacks clear morphological synapomorphies and is highly heterogeneous, so it is difficult to develop a strong case on nonmolecular grounds for their monophyly.
David Ståhlberg - One of the best experts on this subject based on the ideXlab platform.
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polyploid evolution and Plastid DNA variation in the dactylorhiza incarnata maculata complex orchidaceae in scandinavia
Molecular Ecology, 2008Co-Authors: Mikael Hedrén, Sofie Nordström, David StåhlbergAbstract:The Dactylorhiza incarnata/maculata complex (Orchidaceae) was used as a model system to understand genetic differentiation processes in a naturally occurring polyploid complex with much of ongoing diversification and wide distribution in recently glaciated areas in northern Europe. Data were obtained for 12 hypervariable regions in the Plastid DNA genome. A total of 166 haplotypes were found in a sample of 1099 plants. Allopolyploid taxa have inherited their Plastid genomes from D. maculata s.l. Overall haplotype diversity of the combined group of allopolyploid taxa was comparable to that of maternal D. maculata s.l., but populations of allopolyploids were also more strongly differentiated from each other and contained lower numbers of haplotypes than populations of D. maculata s.l. In addition to haplotypes found in extant D. maculata s.l., the allopolyploids also contained several distinct and widespread haplotypes that were not found in any of the parental lineages. Some of these haplotypes were shared between widespread allopolyploids. Divergent allopolyploids with small distributions did not seem to originate from local polyploidization events, but rather as segregates of already existing allopolyploids. Genetic diversification of allopolyploid Dactylorhiza is the result of repeated polyploid formation, secondary hybridization and introgression between already existing polyploids and extant representatives of parental lineages, hybridization between independently derived polyploid lineages, and phyletic diversification in the group of allopolyploids. Although some polyploid taxa must have evolved after the last glaciation, genetic material from the parental lineages has been transferred continuously for longer periods of time. This combination of processes may explain the taxonomic complexity encountered in Dactylorhiza and other polyploid complexes distributed in previously glaciated parts of Europe.
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systematics and phylogeography of the dactylorhiza maculata complex orchidaceae in scandinavia insights from cytological morphological and molecular data
Plant Systematics and Evolution, 2008Co-Authors: David Ståhlberg, Mikael HedrénAbstract:Flow cytometry, morphometry and molecular markers (Plastid DNA and internal transcribed spacers (ITS) of nuclear ribosomal DNA) were used to determine taxonomic and phylogeographic patterns in Dactylorhiza maculata s.l. from Scandinavia. A total of 238 individuals from 27 populations from throughout all of Scandinavia, including the adjacent Kola Peninsula of Russia, were analyzed. Diploid D. maculata ssp. fuchsii and autotetra- ploid D. maculata ssp. maculata are morphologically differentiated. Fragment size variants from 10 Plastid DNA loci (seven microsatellite loci and three loci with indel variation) were combined to give 43 haplotypes. Three major groups of haplotypes were found. Group I haplo- types were prevalent in the north and the northeast, whereas Group II haplotypes were prevalent in the south and the southwest. Group III was represented by only a single haplotype and appeared to be the result of intro- gression from D. incarnata s.l. Group I and Group II haplotypes did not correspond with cytologically and morphologically defined D. maculata ssp. fuchsii or D. maculata ssp. maculata. Past introgressive gene flow rather than recent hybridization is envisaged. Intermediate Group I haplotypes between Group II and the rest of Group I were detected in a zone of contact in central Sweden, which may suggest Plastid DNA recombination. The six ITS alleles scored showed strong positive correlation with taxonomy. All data sets obtained for ssp. maculata were significantly correlated with geography. Three different autotetraploid lineages are hypothesized. One lineage may represent postglacial immigration from the south and the other two lineages may represent eastern immigration routes. Morphology and ITS data suggested that subarctic populations of ssp. maculata should be recognized as var. kolaensis.