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Reinhard Zetter - One of the best experts on this subject based on the ideXlab platform.
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a Winteraceae pollen tetrad from the early paleocene of western greenland and the fossil record of Winteraceae in laurasia and gondwana
Journal of Biogeography, 2018Co-Authors: Friðgeir Grimsson, Guido W Grimm, Alastair J Potts, Reinhard Zetter, Susanne S RennerAbstract:Aim: Winteraceae comprise c.130 species in seven genera, with the greatest species diversity in the Pacific (Pseudowintera, Zygogynum), Australia (Bubbia, Tasmannia), New Guinea (Belliolum, Bubbia, Zygogynum, Tasmannia) and Madagascar (Takhtajania). Only Drimys occurs in South America. Because of their Cretaceous leaves, wood and pollen fossils, and their lack of xylem vessels, Winteraceae throw light on early angiosperm evolution. We describe a Winteraceae pollen tetrad from the Paleocene of Greenland, review the family's fossil record and palaeogeography and document its current climate preferences. Location: Worldwide. Methods: Extant and fossil pollen were studied with light and scanning electron microscopy. Molecular phylogenetic and character mapping approaches were used to infer the evolution of pollen characters, and 37,842 collections from the Global Biodiversity Information Facility were used to infer the climate and vegetation types occupied by today's Winteraceae and to compare them to the Paleocene climate and vegetation of Greenland as inferred from the fossil record of other families. Results: Winteraceae are the only flowering plants with persistent, acalymmate tetrads composed of ulcerate grains with a distinct reticulate sculpturing. The tetrad described here as Pseudowinterapollis agatdalensis Grimsson & Zetter spec. nov. comes from Agatdalen valley in western Greenland and dates to the Early Paleocene, Danian, 64-62Ma. It shows the complete character suite of modern Winteraceae and overlaps the LM characters of the three previously known Pseudowinterapollis species from Australia, New Zealand and South Africa. The palaeoflora of the Agatdal Formation consisted of a mixed deciduous-evergreen forest resembling habitats where Winteraceae occur today. Main conclusions: Macro- and microfossil records of Winteraceae extend back to the Upper Cretaceous in both Laurasia and Gondwana, and the family's biogeography, like that of its sister family, Canellaceae, cannot be understood by focusing only on southern Gondwana. Winteraceae instead were part of broadleaved forests in Paleocene and Eocene North American and Greenland and may have reached Europe via the North Atlantic Land Bridge, explaining Eocene Winteraceae wood in northern Germany.
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Pollen morphology of extant Winteraceae: a study allowing SEM-based affiliation of its fossil representatives
Acta Palaeobotanica, 2017Co-Authors: Friđgeir Grímsson, Alexandros Xafis, Frank Neumann, Reinhard ZetterAbstract:AbstractWhen applying high-resolution microscopy, the pollen morphology of extant taxa can be used to classify fossil pollen, that is, to address the latter in the established systematic-phylogenetic framework. Here we investigate tetrads and pollen features of 20 different Winteraceae species, most of them belonging to the early-diverging generic lineagesTasmannia,DrimysandPseudowintera. The tetrads and pollen are grouped into eleven pollen types based on diagnostic features observed by both light and scanning electron microscopy. The high-resolution scanning electron micrographs of recent material allow detailed comparison with fossil material, resulting in a more accurate affiliation of fossil tetrads/pollen to extant lineages. As a case study, early Miocene Winteraceae tetrads from South Africa are re-examined and formally described. The systematic placement of the African fossils is discussed in light of the pollen types presented here.
Anton Igersheim - One of the best experts on this subject based on the ideXlab platform.
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Floral Structure of Takhtajania and Its Systematic Position in Winteraceae
Annals of the Missouri Botanical Garden, 2000Co-Authors: Peter K Endress, Anton Igersheim, F B Sampson, George E. SchatzAbstract:Floral structure of Takhtajania perrieri, the sole species of Winteraceae in Africa/Madagascar, was studied and compared with that in other Winteraceae. Floral organs are in more or less regular whorls, starting dimerous in the outer perianth region and changing to tetramerous and pentainerous in the inner perianth region and androecium. The innermost androecium whorl is often incomplete. The outer tepal pair is congenitally united, and pairs two and three are postgenitally united in their overlapping area in bud. At the transition from the female to the male phase of anthesis the club-shaped stamen filaments are inflated by cell enlargement, accompanied by starch consumption. The dimerous nature of the unilocular gynoecium is confirmed. The normal linear placentae of the two carpels are oblique to almost horizontal, and therefore the gynoecium does not conform to a usual paracarpous gynoecium with parietal placentation. The ovules are larger than those in other Winteraceae. However, the total evidence of floral features clearly shows the position of Takhtajania in the Winteraceae. Within the family it fits best in the Pseuidowinttera/Zygogynun-clade, which is sister to the Tasmannia/Drimys lade.
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Regular ArticleGynoecium diversity and systematics of the Magnoliales and winteroids
Botanical Journal of the Linnean Society, 1997Co-Authors: Anton IgersheimAbstract:Carpel and ovule structure was compared in representatives of all 11 families of the Magnoliales (Annonaceae, Canellaceae, Degeneriaceae, Eupomatiaceae, Himantandraceae, Magnoliaceae, Myristicaceae) and winteroids (Austrobaileyaceae, Illiciaceae, Schisandraceae, Winteraceae). Special attention was paid to features that are constant at family level. Bisexual flowers are always protogynous. In all representatives studied the carpels are closed at anthesis. Carpel closure is attained in three different ways: (1) postgenital fusion of inner surfaces (Degeneriaceae, Eupomatiaceae, Winteraceae), or (2) occlusion by secretion (Austrobaileyaceae, Schisandraceae), or (3) a combination of (1) and (2): in Annonaceae, Canellaceae, Myristicaceae there is a conspicuous secretory canal in the innermost part of the ventral slit; in Illiciaceae and Magnoliaceae there is a narrow canal in the innermost part of the ventral slit; and in Himantandraceae the ventral slit is postgenitally fused in the style but completely open in the ovary. In most families the carpels have a double stigmatic crest or they have two tips in the transversal symmetry plane (i.e. at right angles to the median plane). Stigmas are unicellular papillate in most families but the papillae are bi- to multicellular (uniseriate) in Degeneriaceae and Eupomatiaceae. An unusual cryptic extracarpellary compitum was found in Himantandraceae and Schisandraceae. Intrusive oil cells were found in the carpel epidermis of Illiciaceae and Schisandraceae. Mature ovules vary in length between 0.15 and 1.1 mm. The outer integument is fully annular (not semiannular) in Degeneriaceae, Himantandraceae, Canellaceae, Myristicaceae, and Illiciaceae. A rudimentary aril occurs in Canellaceae, and originates at the same site as in arillate Annonaceae and Myristicaceae. The results most strongly support an Annonaceae-Myristicaceae-Canellaceae alliance, to some degree also an Eupomatiaceae-Degeneriaceae-Himantandraceae-Magnoliaceae alliance, and an Illiciaceae-Schisandraceae-Winteraceae-Austrobaileyaceae alliance.
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Gynoecium diversity and systematics of the Magnoliales and winteroids
Botanical Journal of the Linnean Society, 1997Co-Authors: Anton IgersheimAbstract:Abstract Carpel and ovule structure was compared in representatives of all 11 families of the Magnoliales (Annonaceae, Canellaceae, Degeneriaceae, Eupomatiaceae, Himantandraceae, Magnoliaceae, Myristicaceae) and winteroids (Austrobaileyaceae, Illiciaceae, Schisandraceae, Winteraceae). Special attention was paid to features that are constant at family level. Bisexual flowers are always protogynous. In all representatives studied the carpels are closed at anthesis. Carpel closure is attained in three different ways: (1) postgenital fusion of inner surfaces (Degeneriaceae, Eupomatiaceae, Winteraceae), or (2) occlusion by secretion (Austrobaileyaceae, Schisandraceae), or (3) a combination of (1) and (2): in Annonaceae, Canellaceae, Myristicaceae there is a conspicuous secretory canal in the innermost part of the ventral slit; in Illiciaceae and Magnoliaceae there is a narrow canal in the innermost part of the ventral slit; and in Himantandraceae the ventral slit is postgenitally fused in the style but completely open in the ovary. In most families the carpels have a double stigmatic crest or they have two tips in the transversal symmetry plane (i.e. at right angles to the median plane). Stigmas are unicellular papillate in most families but the papillae are bi- to multicellular (uniseriate) in Degeneriaceae and Eupomatiaceae. An unusual cryptic extracarpellary compitum was found in Himantandraceae and Schisandraceae. Intrusive oil cells were found in the carpel epidermis of Illiciaceae and Schisandraceae. Mature ovules vary in length between 0.15 and 1.1 mm. The outer integument is fully annular (not semiannular) in Degeneriaceae, Himantandraceae, Canellaceae, Myristicaceae, and Illiciaceae. A rudimentary aril occurs in Canellaceae, and originates at the same site as in arillate Annonaceae and Myristicaceae. The results most strongly support an Annonaceae-Myristicaceae-Canellaceae alliance, to some degree also an Eupomatiaceae-Degeneriaceae-Himantandraceae-Magnoliaceae alliance, and an Illiciaceae-Schisandraceae-Winteraceae-Austrobaileyaceae alliance.
Elizabeth A Zimmer - One of the best experts on this subject based on the ideXlab platform.
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molecular evolution and phylogenetic implications of internal transcribed spacer sequences of ribosomal dna in Winteraceae
American Journal of Botany, 1993Co-Authors: Leonard B. Thien, Helena E. Reeve, Elizabeth A ZimmerAbstract:The internal transcribed spacers and the 5.8S coding region of nuclear ribosomal DNA were sequenced and analyzed to address questions of generic relationships in Winteraceae. The molecular data generated a single tree that is congruent with one based on morphological data. The sequences of ITS 1 in the family range from 235 to 252 bases in size and of ITS 2 from 213 to 226 bases. The size of the 5.8S coding region is 164 bases. The range of ITS 1 and ITS 2 sequence divergence between pairs of genera within Winteraceae is relatively low in comparison to other plant families. Two types of ITS 1 and ITS 2 sequences were observed in the same individual for some taxa. Sequence variations between the two arrays are 4.70/-o 6.3% for ITS 1 and 5. 10/o-7.0% for ITS 2. Both arrays of sequences, however, generate the same phylogenetic relationships. Rates of nucleotide substitutions for the internal transcribed spacers are 3.2-5.2 x 10-'? substitution per site per year estimated in ITS 1 and 3.6-5.7 x 10-'? in ITS 2.
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OF INTERNAL TRANSCRIBED SPACER SEQUENCES OF
1993Co-Authors: Leonard B. Thien, Helena E. Reeve, Elizabeth A ZimmerAbstract:The internal transcribed spacers and the 5.8S coding region of nuclear ribosomal DNA were sequenced and analyzed to address questions of generic relationships in Winteraceae. The molecular data generated a single tree that is congruent with one based on morphological data. The sequences of ITS 1 in the family range from 235 to 252 bases in size and of ITS 2 from 213 to 226 bases. The size of the 5.8S coding region is 164 bases. The range of ITS 1 and ITS 2 sequence divergence between pairs of genera within Winteraceae is relatively low in comparison to other plant families. Two types of ITS 1 and ITS 2 sequences were observed in the same individual for some taxa. Sequence variations between the two arrays are 4.70/-o 6.3% for ITS 1 and 5. 10/o-7.0% for ITS 2. Both arrays of sequences, however, generate the same phylogenetic relationships. Rates of nucleotide substitutions for the internal transcribed spacers are 3.2-5.2 x 10-'? substitution per site per year estimated in ITS 1 and 3.6-5.7 x 10-'? in ITS 2.
F B Sampson - One of the best experts on this subject based on the ideXlab platform.
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Variation and similarities in pollen features in some basal angiosperms, with some taxonomic implications
Plant Systematics and Evolution, 2006Co-Authors: F B SampsonAbstract:Species within three families of basal angiosperms (Trimeniaceae, Winteraceae, Monimiaceae) illustrate differences and similarities in pollen within a species, between species and between genera. Trimenia papuana (Trimeniaceae) has dimorphic pollen (inaperturate, polyforate), each confined to different individual plants. Other species have either disulculate or polyforate pollen. Evolution seems to be from disulculate to inaperturate to polyforate. Present-day Winteraceae have pollen in permanent tetrads except four species of Zygogynum with monads. Why? Did such monads appear as fossils before tetrads in Winteraceae? Molecular studies of Takhtajania perrieri indicate it is basal but its unique bicarpellate unilocular gynoecium seems derived. Although Hedycarya arborea and Kibaropsis caledonica have near-identical permanent pollen tetrads, many other features are very different. Hedycarya species have permanent tetrads or inaperturate monads with spinulose, `starry' or other sculpturing, and it is suggested this and recent molecular data indicate further studies are needed to determine generic limits.
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Floral Structure of Takhtajania and Its Systematic Position in Winteraceae
Annals of the Missouri Botanical Garden, 2000Co-Authors: Peter K Endress, Anton Igersheim, F B Sampson, George E. SchatzAbstract:Floral structure of Takhtajania perrieri, the sole species of Winteraceae in Africa/Madagascar, was studied and compared with that in other Winteraceae. Floral organs are in more or less regular whorls, starting dimerous in the outer perianth region and changing to tetramerous and pentainerous in the inner perianth region and androecium. The innermost androecium whorl is often incomplete. The outer tepal pair is congenitally united, and pairs two and three are postgenitally united in their overlapping area in bud. At the transition from the female to the male phase of anthesis the club-shaped stamen filaments are inflated by cell enlargement, accompanied by starch consumption. The dimerous nature of the unilocular gynoecium is confirmed. The normal linear placentae of the two carpels are oblique to almost horizontal, and therefore the gynoecium does not conform to a usual paracarpous gynoecium with parietal placentation. The ovules are larger than those in other Winteraceae. However, the total evidence of floral features clearly shows the position of Takhtajania in the Winteraceae. Within the family it fits best in the Pseuidowinttera/Zygogynun-clade, which is sister to the Tasmannia/Drimys lade.
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The pollen of Takhtajania perrieri (Winteraceae).
Annals of the Missouri Botanical Garden, 2000Co-Authors: F B SampsonAbstract:Volume: 87Start Page: 380End Page: 38
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Anther and Ovule Development in Tasmannia (Winteraceae)
Australian Journal of Botany, 1992Co-Authors: N Prakash, A. L. Lim, F B SampsonAbstract:Three species of Tasmannia R.Br. ex DC., T. glaucifolia, T. insipida and T. stipitata are studied. The anther is tetrasporangiate and its waU development conforms to the Basic type. The tapetum follows the secretory type of development. Cytokinesis in the microspore mother cells is simultaneous but an evanescent cell plate is present at telophase I and anaphase I1 during meiosis. Pollen tetrads are permanent and tetrahedral. The mature pollen is anaulcerate, reticulate and 2-celled. The ovule. is anatropous, bitegmic and crassinucellate. The micropyle in T. stipitata and T. Glaucifolia is formed by the inner integument only whereas in T. insipida it is formed by both the integuments and is zigzag in outline. Meiosis in the single megaspore mother cell produces a linear or T-shaped megaspore tetrad in T. stipitata and T. glaucifolia but only a linear tetrad in T. insipida. Female gametophyte development is of the monosporic Polygonum type. Fertilisation is porogamous; triple fusion and syngamy occur simultaneously.
Nanette Thomas - One of the best experts on this subject based on the ideXlab platform.
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molecular dating of Winteraceae reveals a complex biogeographical history involving both ancient gondwanan vicariance and long distance dispersal
Journal of Biogeography, 2014Co-Authors: Nanette Thomas, Jeremy J. Bruhl, Andrew Ford, Peter H. WestonAbstract:Aim Our aim was to implement a molecular dating analysis and assess divergence times among taxa of Winteraceae. This enabled us to test hypotheses of vicariance versus long-distance dispersal to explain intercontinental disjunctions in the family. Location Madagascar, Australia (including Lord Howe Island), New Zealand, New Caledonia and South America. Methods We sampled all Australian species and subspecies of Winteraceae. We also included the monotypic Takhtajania perrieri and at least two species of each genus from New Zealand, New Caledonia and South America. Three sets of sequences were combined into one data matrix, including two internal transcribed spacer (ITS) data sets and a trnL–F data set. Both ITS data sets included all genera of Winteraceae, and the paralogous genes identified in Zygogynum s.l. in a previous study were sequenced and aligned in separate ITS data sets. A Bayesian molecular phylogenetic tree of extant Winteraceae was used as a backbone constraint in paup* to establish the placement of fossils. Bayesian analyses were performed using beast, implementing fossil priors to fit lognormal distributions, to test a maximum-parsimony phylogeny and assess divergence times. Results Interspecific relationships generally agreed with previous analyses. In particular, Bubbia comptonii was found to be sister to the rest of the Bubbia/Zygogynum clade, but our analysis has uniquely found sister clades within this group: one from New Caledonia, and one from Australia including Lord Howe Island. The phylogeny yields an age of 91.2 Ma with a 95% confidence interval of 118–67 Ma for crown-group Winteraceae. Main conclusions The estimated age of Takhtajania is consistent with its origin in Madagascar as a result of Gondwanan vicariance – the only angiosperm for which this has been demonstrated with confidence. Differentiation of the rest of this ancient clade is a complicated story of vicariance as a result of the rifting, submergence and exhumation of continents and of long-distance dispersal and extinctions.
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Molecular dating of Winteraceae reveals a complex biogeographical history involving both ancient Gondwanan vicariance and long‐distance dispersal
Journal of Biogeography, 2014Co-Authors: Nanette Thomas, Jeremy J. Bruhl, Andrew Ford, Peter H. WestonAbstract:Aim Our aim was to implement a molecular dating analysis and assess divergence times among taxa of Winteraceae. This enabled us to test hypotheses of vicariance versus long-distance dispersal to explain intercontinental disjunctions in the family. Location Madagascar, Australia (including Lord Howe Island), New Zealand, New Caledonia and South America. Methods We sampled all Australian species and subspecies of Winteraceae. We also included the monotypic Takhtajania perrieri and at least two species of each genus from New Zealand, New Caledonia and South America. Three sets of sequences were combined into one data matrix, including two internal transcribed spacer (ITS) data sets and a trnL–F data set. Both ITS data sets included all genera of Winteraceae, and the paralogous genes identified in Zygogynum s.l. in a previous study were sequenced and aligned in separate ITS data sets. A Bayesian molecular phylogenetic tree of extant Winteraceae was used as a backbone constraint in paup* to establish the placement of fossils. Bayesian analyses were performed using beast, implementing fossil priors to fit lognormal distributions, to test a maximum-parsimony phylogeny and assess divergence times. Results Interspecific relationships generally agreed with previous analyses. In particular, Bubbia comptonii was found to be sister to the rest of the Bubbia/Zygogynum clade, but our analysis has uniquely found sister clades within this group: one from New Caledonia, and one from Australia including Lord Howe Island. The phylogeny yields an age of 91.2 Ma with a 95% confidence interval of 118–67 Ma for crown-group Winteraceae. Main conclusions The estimated age of Takhtajania is consistent with its origin in Madagascar as a result of Gondwanan vicariance – the only angiosperm for which this has been demonstrated with confidence. Differentiation of the rest of this ancient clade is a complicated story of vicariance as a result of the rifting, submergence and exhumation of continents and of long-distance dispersal and extinctions.
