| 1. |
- Kainulainen, Kent, 1978-, et al.
(författare)
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Molecular phylogenetic analysis of the tribe Alberteae (Rubiaceae), with description of a new genus, Razafimandimbisonia
- 2009
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Ingår i: Taxon. - Wien : International Association for Plant Taxonomy. - 0040-0262 .- 1996-8175. ; 58:3, s. 757-768
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Tidskriftsartikel (refereegranskat)abstract
- The tribe Alberteae, presently classified in the subfamily Ixoroideae (Rubiaceae), has historically been an artificial grouping of genera. In the present study, phylogenetic analyses of the chloroplast DNA markers rbcL, ndhF, trnS-G, trnT-F and trnH-psbA as well as the ITS region of the nuclear ribosomal DNA, are done to assess the delimitation of Alberteae. The resulting phylogenetic hypothesis is highly resolved, with most clades strongly supported. The genus Alberta is found to be paraphyletic as presently circumscribed. As a consequence, we propose the new genus Razafimandimbisonia Kainul. & B. Bremer to accommodate the Malagasy species. The newly delimited Alberta is distinguished by having two calycophylls that expand after anthesis as well as awl-shaped stigma lobes. Razafimandimbisonia is distinguished from the remaining Alberteae by having dehiscent fruits and anthers without basal appendages. We demonstrate that the genera Airosperma, Boholia and Crossopteryx are not associated with Alberteae, as has previously been suggested. Alberteae is considered restricted to the genus Alberta endemic to Southeast Africa, and the two Malagasy endemic genera Nematostylis and Razafimandimbisonia.
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| 2. |
- Larsén, Eva, et al.
(författare)
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Phylogeny of Merlin's grass (Isoetaceae) : revealing an Amborella syndrome and the importance of geographic distribution for understanding current and historical diversity
- 2022
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Ingår i: BMC Ecology and Evolution. - : Springer Science and Business Media LLC. - 2730-7182. ; 22:1
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Tidskriftsartikel (refereegranskat)abstract
- Background: Merlin's grass (Isoetes, Isoetaceae, Lycopsida), is the extant remnant of the isoetalean wood-producing lycopsids that originated during the Paleozoic, possibly in aquatic or boggy habitats. Modern day species are aquatic, semi-aquatic or terrestrial and occur almost worldwide. They display little morphological variation; the lobed corm has helically arranged leaves with internal air channels and basal sporangia. Genetic variation has also proven limited, which has hampered phylogenetic inference. We investigate evolutionary relationships in Isoetes, using molecular data and an extended sample of species compared to previous work, adding species that have never before been included in a phylogenetic study.Results: Our results reveal an unexpected discovery of an Amborella syndrome in Isoetaceae: a single poorly known species is sister to the remaining family. The species, Isoetes wormaldii, is a rare endemic to the Eastern Cape of South Africa. Its leaves are flattened with a rounded point, which sharply contrasts with the awl-shaped leaves of most other species of Isoetes. The remaining species of Isoetes are resolved in five major clades, also indicated in previous work. While the phylogeny shows geographic structure, the patterns are complex. For example, tropical-southern African species occur in at least five clades, and Indian, Australian and Mediterranean species in at least three clades each.Conclusion: The evolutionary and biogeographical history of Isoetes is not easily explained, and may conceivably include ample extinction and a mixture of ancient and more recent processes. Previously shown difficulties with node age estimation increase the problem. The here demonstrated sister-relationship between the phylogenetically, morphologically and genetically distinct Isoetes wormaldii and the remaining family appears to bridge the morphological gap between Isoetes and its extinct relatives, although further studies are needed. Moreover, it shortens the branch length to its living sister genus Selaginella, and may enhance node age estimation in future studies. Isoetes wormaldii is critically endangered, known only from one (to a few) minor populations. Immediate actions need to be taken if we want to prevent this unique species from going extinct.
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| 3. |
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| 4. |
- Mouly, Arnaud, et al.
(författare)
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Phylogeny and classification of the species-rich pantropical showy genus Ixora (Rubiaceae-Ixoreae) with indications of geographical monophyletic units and hybrids
- 2009
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Ingår i: American Journal of Botany. - : Wiley. - 0002-9122 .- 1537-2197. ; 96, s. 686-706
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Tidskriftsartikel (refereegranskat)abstract
- Species-rich genera often have various conflicting circumscriptions from independent regional fl ora treatments. Testing the monophyly of these groups of plants is an important step toward the establishment of a phylogenetic classifi cation. The genus Ixora of the tribe Ixoreae in the subfamily Ixoroideae (coffee family or Rubiaceae) is a species-rich pantropical genus of ca. 500 species. Phylogenetic analyses of Ixoreae based on combined sequence data from one nuclear (nrETS) and two chloroplast ( rps16 and trnT-F ) markers reveal the paraphyly of Ixora as presently delimited and also show that the tribe can be subdivided into three major clades: the Mascarene/neotropical/Malagasy/African clade, the Pacifi c clade, and the Asian clade. Given the lack of morphological synapomorphies supporting the different Ixora clades and the morphological consistency of the ingroup taxa, we propose a broad circumscription of Ixora including all its satellite genera: Captaincookia , Doricera , Hitoa , Myonima , Sideroxyloides , Thouarsiora, and Versteegia . The current infrageneric classifi cation of Ixora is not supported. The different Ixora subclades represent geographical units. Nuclear and chloroplast tree topologies were partially incongruent, indicating at least four potential natural hybridization events. Other confl icting positions for the cultivated species are most likely due to anthropogenic hybridization.
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| 5. |
- Razafimandimbison, Sylvain G., et al.
(författare)
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PHYLOGENY AND GENERIC LIMITS IN THE SISTER TRIBES PSYCHOTRIEAE AND PALICOUREEAE (RUBIACEAE) : EVOLUTION OF SCHIZOCARPS IN PSYCHOTRIA AND ORIGINS OF BACTERIAL LEAF NODULES OF THE MALAGASY SPECIES
- 2014
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Ingår i: American Journal of Botany. - : Wiley. - 0002-9122 .- 1537-2197. ; 101:7, s. 1102-1126
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Tidskriftsartikel (refereegranskat)abstract
- Premise of the study: The pantropical, species-rich Psychotrieae and Palicoureeae are sister tribes of mostly drupe-bearing and nonbacterial leaf-nodulating species with problematic generic limits. This problem is more complicated in Psychotrieae due to the paraphyly of the genus Psychotria, the lack of diagnostic characters for some major lineages, and the poor sampling from some biodiversity hotspots. Schizocarps and bacterial leaf nodules have been used for recognizing formal groups in Psychotrieae, but their evolution and taxonomic value have not been studied using a robust phylogeny of the tribe. Methods: We analyzed 287 samples from the entire ranges of the tribes, with particular emphasis on the Western Indian Ocean region, with the Bayesian Markov chain Monte Carlo method. Key results: All allied Psychotria genera investigated are nested within a paraphyletic Psychotria. Schizocarps evolved independently two times within Psychotria, and one reversal back to the drupaceous condition is inferred. The Malagasy leaf-nodulated Psychotrieae (except Apomuria bullata) and the Comorian non-leaf-nodulated Psychotria conocarpa are nested within the (African) leaf-nodulated clade. Within Palicoureeae, Chassalia is paraphyletic with respect to Geophila sensu stricto, and the Malagasy Geophila gerrardii and the African Hymenocoleus are closely related. Conclusions: A widely circumscribed Psychotria encompassing the entire Psychotrieae is supported. Within Psychotria, two separate origins of schizocarps from drupes, one reversal back to the drupaceous condition, and two independent origins of the Malagasy leafnodulated species are inferred. A new genus Puffia is described to accommodate Geophila gerrardii, and a narrow circumscription of Chassalia is adopted. Thirty-two new combinations, two lectotypifications, and 25 new names are presented.
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| 6. |
- Razafimandimbison, Sylvain, 1964-, et al.
(författare)
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Phylogeny of the Madagascar-centred tribe Danaideae (Rubiaceae) as a precursor of taxonomic revision: insights into its generic and species limits, affinities and distribution
- 2022
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Ingår i: Annals of Botany. - : Oxford University Press (OUP). - 0305-7364 .- 1095-8290. ; 130, s. 849-867
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Tidskriftsartikel (refereegranskat)abstract
- Background and aims The tribe Danaideae (Rubiaceae) is almostexclusively endemic to the Western Indian Ocean Region (WIOR), encompassing thegenera Danais, Payera and Schismatoclada that occur in humid and sub-humidclimates. Much of the species diversity is endemic to restricted, remote and/ormountainous areas of the WIOR, and recent field work on Madagascar indicatessubstantial unknown diversity of the Danaideae. Further, the monophyly of theMalagasy genera Payera and Schismatoclada has been questioned in previous work,species delimitations and phylogenetic relationships within the genera are poorlyunderstood, and distribution and evolution of gross morphological features have notbeen assessed. Methods We conducted morphological investigations, and produced robustphylogenies of Danaideae based on nuclear and plastid sequence data from 193terminals. Ample plant material has been newly collected in the WIOR for thepurpose of the present study, including potentially new species unknown to science.We performed Bayesian non-clock and relaxed-clock analyses employing threealternative clock models of a dataset with a dense sample of taxa from the entiregeographic ranges of Danaideae. Based on the results, we discuss species diversityand distribution, relationships, and morphology in Danaideae. Key results Our results demonstrate the monophyly of Danaideae, its threegenera, and 43 species. Nine species are resolved as non-monophyletic. Manygeographically distinct but morphologically heterogeneous lineages were identified,and morphological features traditionally considered diagnostic of subgroups of thegenera, used e.g. in species identification keys, are not clade-specific. Conclusions Our results demonstrate that Madagascar contains ample heretoundocumented morphological and species diversity of Danaideae. Our novel approachto perform molecular phylogenetic analyses as a precursor to taxonomic revisionsprovides numerous benefits for the latter. There are tentative indications of parallelnorthward diversification in Payera and Schismatoclada on Madagascar, and ofgeographic phylogenetic clustering despite the anemochorous condition of Danaideae
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| 7. |
- Rydin, Catarina, et al.
(författare)
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Evolutionary relationships in the Spermacoceae alliance (Rubiaceae) using information from six molecular loci : insights into systematic affinities of Neohymenopogon and Mouretia
- 2009
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Ingår i: Taxon. - Wien : International Association for Plant Taxonomy. - 0040-0262 .- 1996-8175. ; 58:3, s. 793-810
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Tidskriftsartikel (refereegranskat)abstract
- Several recent phylogenetic studies of Rubiaceae have dealt with enigmatic taxa whose systematic positions have been previously unknown or controversial. We address evolutionary relationships in the Spermacoceae alliance (Rubioideae) with special emphasis on the Asian genera Mouretia and Neohymenopogon, here sequenced for the first time. Both genera belong in the tribe Argostemmateae and have persistent calyx lobeson the fruit in common with Argostemma and Mycetia. Other previous uncertainties are resolved with strong support; Saprosma is sister to Paederieae s.str. and Carpacoce is sister to remaining Anthospermeae. Our results further reveal some phylogenetic problems. Danaideae is sister to remaining taxa in the Spermacoceae alliance with high posterior probability, which contradicts results in a recent study. The uncertainty concerning evolutionary relationships of Dunnia and Theligonum is reinforced, despite a denser taxon sampling in the Spermacoceae alliance compared with earlier studies. We also demonstrate yet another example of the controversial correlation between molecular substitution rate and plant life history.
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| 8. |
- Rydin, Catarina, et al.
(författare)
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The female reproductive unit of Ephedra (Gnetales) : comparative morphology and evolutionary perspectives
- 2010
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Ingår i: Botanical journal of the Linnean Society. - : Wiley. - 0024-4074 .- 1095-8339. ; 163:4, s. 387-430
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Tidskriftsartikel (refereegranskat)abstract
- Morphological variation in Ephedra (Gnetales) is limited and confusing from an evolutionary perspective, with parallelisms and intraspecific variation. However, recent analyses of molecular data provide a phylogenetic framework for investigations of morphological traits, albeit with few informative characters in the investigated gene regions. We document morphological, anatomical and histological variation patterns in the female reproductive unit and test the hypothesis that some Early Cretaceous fossils, which share synapomorphies with Ephedra, are members of the extant clade. Results indicate that some morphological features are evolutionarily informative although intraspecific variation is evident. Histology and anatomy of cone bracts and seed envelopes show clade-specific variation patterns. There is little evidence for an inclusion of the Cretaceous fossils in the extant clade. Rather, a hypothesized general pattern of reduction of the vasculature in the ephedran seed envelope, probably from four vascular bundles in the fossils, to ancestrally three in the living clade, and later to two, is consistent with phylogenetic and temporal analyses, which indicate that extant diversity evolved after the Cretaceous-Tertiary boundary. Notwithstanding striking similarities between living and Cretaceous Ephedra, available data indicate that the Mesozoic diversity went almost entirely extinct in the late Cretaceous causing a bottleneck effect in Ephedra, still reflected today by an extraordinarily low level of genetic and structural diversity.
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| 9. |
- Thureborn, Olle, et al.
(författare)
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Phylogeny of Anthospermeae of the coffee family inferred using clock and nonclock models
- 2019
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Ingår i: International Journal of Plant Sciences. - : University of Chicago Press. - 1058-5893 .- 1537-5315. ; 180:5, s. 386-402
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Tidskriftsartikel (refereegranskat)abstract
- Premise of research. With wind-pollinated flowers and partly temperate distribution, the tribe Anthospermeae stands out in the otherwise mostly animal-pollinated and tropical coffee family (Rubiaceae). Nevertheless, few attempts to resolve the phylogeny of the group have been made, and inter- and infrageneric relationships have been only partly addressed. Here we investigate evolutionary relationships and generic and subtribal delimitations of Anthospermeae. We assess the influence of alternative evolutionary rate models on topology and node support.Methodology. Using sequence data from the nuclear (nrITS and nrETS) and plastid (atpB-rbcL, ndhF, rbcL, rps16, and trnT-trnF) genomes collected for a broad sample of taxa, we conducted Bayesian analyses using nonclock, strict clock, and relaxed clock models. The resulting topologies and support values were compared, and the relative fit of evolutionary models to our data was evaluated. Marginal likelihood estimates were used to discriminate between the competing rate models.Pivotal results. The monophyly of Anthospermeae was confirmed with Carpacoceresolved as sister to the remaining species. We found several cases of supported topological conflict between results based on nuclear and plastid data, but the deepest splits of the tribe were congruent among all analyses and incompatible with traditional subtribal delimitations of Anthospermeae. Monophyly of the genera Anthospermum, Nenax, and Coprosma was not supported. While the relaxed clock model was consistently favored over the nonclock and strict clock models for all data sets, the use of the different models had little impact on phylogenetic results.Conclusions. We propose a revised subtribal classification of Anthospermeae, including a new subtribe, the monogeneric Carpacocinae. Introgression/hybridization and incomplete lineage sorting are the most likely causes for the plastid-nuclear incongruences detected for Anthospermeae, but their relative contribution could not be concluded.
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| 10. |
- Wikström, Niklas, et al.
(författare)
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No phylogenomic support for a Cenozoic origin of the “living fossil” Isoetes
- 2023
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Ingår i: American Journal of Botany. - : Wiley. - 0002-9122 .- 1537-2197. ; 110:1
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Tidskriftsartikel (refereegranskat)abstract
- Premise: The isoetalean lineage has a rich fossil record that extends to the Devonian, but the age of the living clade is unclear. Recent results indicate that it is young, from the Cenozoic, whereas earlier work based on less data from a denser taxon sampling yielded Mesozoic median ages.Methods: We analyzed node ages in Isoetes using two genomic data sets (plastome and nuclear ribosomal cistron), three clock models implemented in MrBayes (ILN, WN, and TK02 models), and a conservative approach to calibration.Results: While topological results were consistently resolved in Isoetes estimated crown group ages range from the latest Paleozoic (mid-Permian) to the Mesozoic depending on data type and clock model. The oldest estimates were retrieved using the autocorrelated TK02 clock model. An (early) Cenozoic age was only obtained under one specific condition (plastome data analyzed with the uncorrelated ILN clock model). That same plastome data set also yielded the oldest (mid-Permian) age estimate when analyzed with the autocorrelated TK02 clock model. Adding the highly divergent, recently established sister species Isoetes wormaldii to the data set approximately doubled the average median node depth to the Isoetes crown group.Conclusions: There is no consistent support for a Cenozoic origin of the living clade Isoetes. We obtained seemingly well-founded, yet strongly deviating results depending on data type and clock model. The single most important future improvement is probably to add calibration points, which requires an improved understanding of the isoetalean fossil record or alternative bases for calibration.
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