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  • 1.
    Andreasen, Katarina
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Organismal Biology, Systematic Biology.
    Phylogeny, Hybridization, and Evolution of Habit and Breeding System in Sidalcea and Eremalche (Malvaceae)2012In: International journal of plant sciences, ISSN 1058-5893, E-ISSN 1537-5315, Vol. 173, no 5, p. 532-548Article in journal (Refereed)
    Abstract [en]

    Reconstructing the phylogeny of the western North American Sidalcea-Eremalche lineage provides an opportunity to study the evolution of different fundamental traits considered to play an important role in plant evolution. These plants display different life-history strategies, such as annual and perennial habit and hermaphroditic and gynodioecious breeding systems, enabling evolutionary investigation of these traits in a phylogenetic context. Difficult species delimitations have been suggested to be caused by hybridization in combination with polyploidy. Molecular phylogenetic analyses based on sequences of the chloroplast intron rpl16 and nuclear ribosomal DNA show that the genera are strongly supported as monophyletic sister lineages, and the polytomy in Sidalcea in both data sets likely represents a rapid radiation event. Coastal California is indicated as ancestral area for Sidalcea, in agreement with earlier biogeographical hypotheses. Hybridization hypotheses gained support from the chloroplast DNA data for the hexaploid Sidalcea lineage and for S. sparsifolia and S. pedata. Sidalcea section Annuae, including the annuals, represents a paraphyletic assemblage. The shift between annual and perennial habit must have happened at least four times, but reversals to perenniality appear unlikely. At least five reversals from the gynodioecious to the hermaphroditic condition are inferred, possibly due to population bottlenecks in some lineages.

  • 2.
    Bengtson, Annika
    et al.
    Stockholm University, Faculty of Science, Department of Botany.
    Anderberg, Arne A.
    Karis, Per Ola
    Stockholm University, Faculty of Science, Department of Botany.
    PHYLOGENY AND GENERIC DELIMITATION OF THE METALASIA CLADE (ASTERACEAE-GNAPHALIEAE)2011In: International journal of plant sciences, ISSN 1058-5893, E-ISSN 1537-5315, Vol. 172, no 8, p. 1067-1075Article in journal (Refereed)
    Abstract [en]

    The Metalasia clade, which consists of the genus Metalasia and a number of much smaller satellite genera, is a South African group in the tribe Gnaphalieae (Asteraceae). This study scrutinizes the phylogenetic relationships of the Metalasia clade by means of chloroplast (trnL-trnF, psbA-trnH) and nuclear (external transcribed spacer, internal transcribed spacer) sequence data. The Metalasia clade is confirmed to be a monophyletic group, and the phylogenetic positions of the included genera are determined. The genus Metalasia may be monophyletic if the monotypic Planea is included, but the node has very poor support and further studies are needed. The Metalasia species fall into two well-supported groups, distinguishing the members of Karis's Metalasia densa group from the others. Lachnospermum is shown to be monophyletic and is placed as a possible sister group to Metalasia. Phaenocoma is placed as sister to the branch consisting of Metalasia and Lachnospermum. Calotesta, Hydroidea, and Atrichantha form a clade, with the monotypic Dolichothrix as their sister group.

  • 3.
    Bisang, Irene
    et al.
    Swedish Museum of Natural History, Department of Botany.
    Hedenäs, Lars
    Swedish Museum of Natural History, Department of Botany.
    Males Are Not Shy in the Wetland Moss Drepanocladus lycopodioides2013In: International journal of plant sciences, ISSN 1058-5893, E-ISSN 1537-5315, Vol. 174, no 5, p. 733-739Article in journal (Refereed)
    Abstract [en]

    Premise of research. Maintenance of dioecious and monoecious sexual systems at nearly equal frequencies, infrequent sexual expression, and distinctly female-skewed sex ratios among the dioecious species are reproductive characteristics of bryophytes, which are otherwise unusual among embryophytes. Most sex ratio assessments to date have relied on gametophytes forming sexual organs, and how these reflect genetic genders is largely unresolved.

    Methodology. For the European wetland moss Drepanocladus lycopodioides, we ask whether the adult expressed sex ratio is more strongly female biased than the “true” population sex ratio based on genetically male and female plants, i.e., whether males exhibit a lower sex expression rate than females (shy males). We assess expressed sex ratio on the basis of sex expression in individually scored herbarium specimens. We directly and on a large geographic scale assess nonexpressed sex ratio, for the second time in a moss, by sexing individual shoots from nonexpressing specimens using a molecular sex marker.

    Pivotal results. On the basis of the female and male frequencies in these two data sets and the overall proportion of expressing specimens, we estimate the European population sex ratio as 2.6 : 1 (female to male). All three sex ratios are significantly female skewed and do not significantly differ from each other, indicating that there is no gender difference in sex expression rates.

    Conclusions. These results and previous data for Drepanocladus trifarius show that males are not shy in the two wetland mosses of markedly different habitats.

  • 4.
    Bomfleur, Benjamin
    et al.
    Swedish Museum of Natural History, Department of Paleobiology.
    Decombeix, Anne-Laure
    Schwendemann, Andrew
    Escapa, Ignacio
    Taylor, Edith
    Taylor, Thomas
    McLoughlin, Stephen
    Swedish Museum of Natural History, Department of Paleobiology.
    Habit and Ecology of the Petriellales, an Unusual Group of Seed Plants from the Triassic of Gondwana2014In: International journal of plant sciences, ISSN 1058-5893, E-ISSN 1537-5315, Vol. 175, no 9, p. 1062-1075Article in journal (Refereed)
    Abstract [en]

    Premise of research. Well-preserved Triassic plant fossils from Antarctica yield insights into the physiology of plant growth under the seasonal light regimes of warm polar forests, a type of ecosystem without any modern analogue. Among the many well-known Triassic plants from Antarctica is the enigmatic Petriellaea triangulata, a dispersed seedpod structure that is considered a possible homologue of the angiosperm carpel. However, the morphology and physiology of the plants that produced these seedpods have so far remained largely elusive.

    Methodology. Here, we describe petriellalean stems and leaves in compression and anatomical preservation that enable a detailed interpretation of the physiology and ecology of these plants.

    Pivotal results. Our results indicate that the Petriellales were diminutive, evergreen, shade-adapted perennial shrubs that colonized the understory of the deciduous forest biome of polar Gondwana. This life form is very unlike that of any other known seed-plant group of that time. By contrast, it fits remarkably well into the “dark and disturbed” niche that some authors considered to have sheltered the rise of the flowering plants some 100 Myr later.

    Conclusions. The hitherto enigmatic Petriellales are now among the most comprehensively reconstructed groups of extinct seed plants and emerge as promising candidates for elucidating the mysterious origin of the angiosperms.

  • 5.
    Borg, Agneta Julia
    et al.
    Stockholm University, Faculty of Science, Department of Botany.
    Schoenenberger, Juerg
    Comparative floral development and structure of the black mangrove genus Avicennia L. and related taxa in the Acanthaceae2011In: International journal of plant sciences, ISSN 1058-5893, E-ISSN 1537-5315, Vol. 172, no 3, p. 330-344Article in journal (Refereed)
    Abstract [en]

    Phylogenetic relationships of Avicennia have been difficult to trace because of the presence of convergent characters related to the mangrove environment. Recent molecular data suggest a close relationship to Thunbergioideae, a subfamily within Acanthaceae (Lamiales), but morphological support for the new findings has been equivocal. Floral structure and development are comparatively studied here in three species of Avicennia, with special attention given to the ovary and the ovules, which are also studied in Thunbergioideae. The suggested sister group relationship of Avicennia and Thunbergioideae is supported by three synapomorphies: (1) collateral ovule arrangement, (2) vertical orientation of ovule curvature, and (3) an exposed nucellus that is contiguous with the ovary wall, at least during early stages of ovule development. We interpret the latter character as a neotenic feature that is retained in the anthetic ovules of Avicennia. We confirm that the apparently tetramerous flowers of Avicennia have a basically pentamerous floral ground plan. Additional floral characters shared between Avicennia and Thunbergioideae include left contort corolla aestivation, thickened filament bases with glandular hairs, presence of pollen sac placentoids, and various aspects of fruit morphology and embryology. However, these features are either symplesiomorphic or are not known well enough to allow for unequivocal conclusion on character evolution in Acanthaceae.

  • 6.
    Bremer, Birgitta
    et al.
    Stockholm University, Faculty of Science, The Bergius Botanical Garden Museum. Stockholm University, Faculty of Science, Department of Botany.
    Eriksson, Torsten
    Stockholm University, Faculty of Science, The Bergius Botanical Garden Museum. Stockholm University, Faculty of Science, Department of Botany.
    Timetree of Rubiaceae - Phylogeny and dating the family, subfamilies and tribes2009In: International journal of plant sciences, ISSN 1058-5893, E-ISSN 1537-5315, Vol. 170, no 6, p. 766-793Article in journal (Refereed)
    Abstract [en]

    Rubiaceae are one of the largest families of plants, with ;13,000 species. In this study, we have estimated the phylogeny for 534Rubiaceae taxa from329 generawith up to five different chloroplast regions by Bayesian analysis. It resulted in a highly resolved tree with many strongly supported nodes. There is strong support for the three subfamilies (Cinchonoideae, Ixoroideae, Rubioideae) and most of the 44 included tribes. A scaled-down data set of 173 Rubiaceae taxawas usedwith a Bayesian approach to estimate divergence times for clades classified as tribes and subfamilies. Four fossils were used as minimum age priors, one inside each subfamily and one for Rubiaceae as a whole (Faramea-type pollen, Scyphiphora pollen, Cephalanthus pusillus fruits, and Paleorubiaceophyllum eocenicum leaves). The estimated lineage (stem) divergence time for Rubiaceae is 90.4Ma. The estimated lineage divergence times for the subfamilies are 84.4 (86.6)Ma for Rubioideae, 73.1Ma for Ixoroideae, and 73.1Ma for Cinchonoideae.The estimated lineage divergence times for the tribes vary between 86.6 and 14.2Ma. Classification, relationships, geographical distribution, and age estimates are presented and discussed for all tribes.

  • 7. Bränn, Kristina Holmen
    et al.
    Lehtilä, Kari
    Södertörn University College, School of Life Sciences.
    Maternal plant responses to high pollen loads2007In: International journal of plant sciences, ISSN 1058-5893, E-ISSN 1537-5315, Vol. 168, no 7, p. 1013-1019Article in journal (Refereed)
    Abstract [en]

    Maternal plant responses to different levels of pollination vary and are of importance for the total fitness of the plant. We studied how varying pollen load affects late flowering, reproduction, and growth of maternal plants. Raphanus raphanistrum, Sinapis arvensis, and Brassica napus were used as study species. We conducted hand- pollination experiments with different pollen loads for early flowers in the inflorescence and measured responses on vegetative traits, floral traits of late flowers, and seed production. There were no effects on vegetative traits, but floral traits were affected by treatments in two of the study species. The high pollen load treatment in S. arvensis resulted in longer petals on late flowers compared with the low pollen load treatment. In R. raphanistrum, the high pollen load treatment resulted in a higher number of flowers, with narrower petals, than the low pollen load treatment. Total seed production was similar in both treatments in all species. Our results suggest that plants that received a high pollen load were able to allocate resources to high seed production of early flowers and to increased pollen dispersal of late flowers, thereby achieving higher total fitness than plants that received a lower pollen load.

  • 8.
    Friis, Else Marie
    et al.
    Swedish Museum of Natural History, Department of Paleobiology.
    Crane, Peter Robert
    Oak Spring Gardens.
    Pedersen, Kaj Raunsgaard
    Aarhus University.
    Chlamydospermous seeds document the diversity andabundance of extinct gnetalean relatives in Early Cretaceous vegetation2019In: International journal of plant sciences, ISSN 1058-5893, E-ISSN 1537-5315, Vol. 180, p. 643-666Article in journal (Refereed)
    Abstract [en]

    Premise of research. The recognition of diverse and abundant chlamydospermous seeds from the Early Cretaceous of Denmark, Portugal, and eastern North America has been an unexpected outcome of studies of mesofloras that were initially focused on early angiosperms. These seeds provide structural information critical for understanding morphological and structural diversity in an important Mesozoic group of extinct gnetalean relatives.

    Methodology. The fossil seeds were picked from Early Cretaceous mesofossil floras from localities in western Portugal and Virginia using a stereomicroscope. Selected seeds were studied in more detail for morphological and anatomical traits using SEM and synchrotron radiation X-ray tomographic microscopy.

    Pivotal results. Six new species of chlamydospermous seeds are described that add substantially to the known diversity of Early Cretaceous chlamydosperms. In general seed organization, the fossils are similar to seeds of extant Gnetales, but none of the fossils can be assigned to any of the three living genera of Gnetales (Ephedra, Gnetum, and Welwitschia). All six species have similar closure of the micropylar canal but show considerable variation in the anatomy of the seed envelope. In micropylar closure, the fossils are most similar to extant Gnetum, but they differ in other respects from seeds of extant Gnetum, and one of the new seed taxa has polyplicate, ephedroid pollen in the micropyle. A well-preserved embryo with two cotyledons is preserved in seeds of Rothwellia foveata and provides the first information on the embryo in this Early Cretaceous chlamydospermous complex.

    Conclusions. The chlamydospermous seeds described here show similarities to seeds of extant Gnetales. However, most of the fossils exhibit combinations of features that are unknown among extant species of Gnetales and clearly represent an extinct complex of plants that were important in Early Cretaceous vegetation, along with other extinct plant groups, including Bennettitales and Erdtmanithecales.

  • 9.
    Friis, Else Marie
    et al.
    Swedish Museum of Natural History, Department of Paleobiology.
    Crane, Peter Robert
    Oak Spring Gardens.
    Pedersen, Kaj Raunsgaard
    Aarhus University.
    Hedyosmum-like fossils in the Early Cretaceous diversification of angiosperms2019In: International journal of plant sciences, ISSN 1058-5893, E-ISSN 1537-5315, Vol. 180, p. 232-239Article in journal (Refereed)
    Abstract [en]

    Premise of research. Early Cretaceous Hedyosmum-like fossils are important because they provide information on the pistillate flowers and fruits of plants that produced Asteropollis pollen, which is common and widely distributed very early in the history of angiosperms. Hedyosmum (Chloranthaceae) is also the only extant genus for which there is a plausible fossil presence at such an early stage of angiosperm evolution.

    Methodology. The fossils were sieved out of unconsolidated sediments and cleaned with HF, HCl, and water. External morphology and internal anatomy were studied using scanning electron microscopy and synchrotron radiation X-ray tomographic microscopy.

    Pivotal results. New information on Hedyosmum-like fossils is provided based on pistillate flowers and fruits with adhering Asteropollis pollen from the Early Cretaceous of Portugal. The fossils are assigned to a new Early Cretaceous taxon, Hedyflora crystallifera, which in external morphology is closely similar to extant Hedyosmum. However, the fossils differ from the extant genus in having a crystalliferous endotesta with cells that have endoreticulate infillings, a feature characteristic of all extant Chloranthaceae except Hedyosmum. Extant Hedyosmum has a thin, unspecialized seed coat. This new discovery confirms earlier predictions that an endotestal seed coat is ancestral for Chloranthaceae as a whole but has been lost in the lineage leading to extant Hedyosmum.

    Conclusions. Hedyflora confirms the divergence of the Hedyosmum lineage from other Chloranthaceae very early in the angiosperm radiation but refutes these early fossils as evidence of extant Hedyosmum in the Early Cretaceous.

  • 10.
    Friis, Else Marie
    et al.
    Swedish Museum of Natural History, Department of Paleobiology.
    Crane, Peter Robert
    Pedersen, Kaj Raunsgaard
    SAPORTANTHUS, AN EXTINCT GENUS OF LAURALESFROM THE EARLY CRETACEOUS OF PORTUGAL2017In: International journal of plant sciences, ISSN 1058-5893, E-ISSN 1537-5315, Vol. 178, no 8, article id 650–672Article in journal (Refereed)
  • 11.
    Granberg, Åsa
    et al.
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences.
    Carlsson-Granér, Ulla
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences.
    Arnqvist, Per
    Giles, Barbara E
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences.
    Variation in breeding system traits within and among populations of Microbotryum violaceum on Silene dioica2008In: International journal of plant sciences, ISSN 1058-5893, E-ISSN 1537-5315, Vol. 169, no 2, p. 293-303Article in journal (Refereed)
    Abstract [en]

    Breeding systems exert profound effects on the amount and distribution of genetic diversity within and among populations. Knowledge of breeding systems is also important for understanding dynamics between coevolving organisms, e.g., pathogen‐host interactions. Here we study the breeding system of the obligate anther smut Microbotryum violaceum on Silene dioica. Microbotryum violaceum is capable of both inbreeding and outcrossing, but several recent studies on other host races have indicated that automixis via intrapromycelial mating is the predominant breeding system. Compared with conjugations between cells from different meioses, automixis results in slower loss of heterozygosity and faster production of infectious hypha. However, high rates of intrapromycelial matings have been suggested to invoke a fitness cost due to production of fewer infectious dikaryons. Working with single strains under standardized laboratory conditions, we studied traits that could influence the distribution of genetic variability and pathogen fitness. We found that intrapromycelial mating is the dominant conjugation form for M. violaceum var. dioica but that the breeding system varies, partly because of genetic differences, both within and among populations. Further, we did not find the predicted fitness reduction for intrapromycelial matings, suggesting that intrapromycelial mating is a highly favorable breeding system for M. violaceum.

  • 12.
    Holmén Bränn, Kristina
    et al.
    Stockholm University, Faculty of Science, Department of Botany.
    Lehtilä, K.
    Maternal plant responses to high pollen loads2007In: International journal of plant sciences, ISSN 1058-5893, E-ISSN 1537-5315, Vol. 168, no 7, p. 1013-1019Article in journal (Refereed)
    Abstract [en]

    Maternal plant responses to different levels of pollination vary and are of importance for the total fitness of the plant. We studied how varying pollen load affects late flowering, reproduction, and growth of maternal plants. Raphanus raphanistrum, Sinapis arvensis, and Brassica napus were used as study species. We conducted hand‐pollination experiments with different pollen loads for early flowers in the inflorescence and measured responses on vegetative traits, floral traits of late flowers, and seed production. There were no effects on vegetative traits, but floral traits were affected by treatments in two of the study species. The high pollen load treatment in S. arvensis resulted in longer petals on late flowers compared with the low pollen load treatment. In R. raphanistrum, the high pollen load treatment resulted in a higher number of flowers, with narrower petals, than the low pollen load treatment. Total seed production was similar in both treatments in all species. Our results suggest that plants that received a high pollen load were able to allocate resources to high seed production of early flowers and to increased pollen dispersal of late flowers, thereby achieving higher total fitness than plants that received a lower pollen load.

  • 13. Ickert-Bond, Stefanie M.
    et al.
    Rydin, Catarina
    Stockholm University, Faculty of Science, Department of Botany.
    MICROMORPHOLOGY OF THE SEED ENVELOPE OF EPHEDRA L. (GNETALES) AND ITS RELEVANCE FOR THE TIMING OF EVOLUTIONARY EVENTS2011In: International journal of plant sciences, ISSN 1058-5893, E-ISSN 1537-5315, Vol. 172, no 1, p. 36-48Article in journal (Refereed)
    Abstract [en]

    Micromorphology of the seed envelope of Ephedra (Gnetales) is known to be variable, but variation patterns have never been systematically documented. We test the usefulness of this feature for species determination and subclade delimitation in Ephedra and investigate the relationship of this character to infrageneric evolutionary patterns. Most species have a basically smooth seed envelope, which in some species appears slightly striate or reticulate due to convex or depressed outer periclinal cell walls. Ephedra rhytidosperma from China and Ephedra torreyana from North America have transverse lamellae formed by the epidermis. A papillate surface is found in respective close relatives of these two species. Micromorphology of the seed envelope is generally not useful for species identification or subclade delineation. The amount of variation is low, and intraspecific variation, which in some cases seems to be correlated with hybridization and/or introgression, complicates species recognition. Furthermore, parallel evolution of similar micromorphological patterns in unrelated subclades of Ephedra is evident and cannot be explained by similar seed dispersal mechanisms. The Asian species with transverse lamellae or papillae on the seed are dispersed by frugivores whereas similar American species are anemochoric. Transverse ridges occur in several Early Cretaceous fossil seeds with affinity to Ephedra. However, our results indicate that the resemblance between these fossils and extant taxa with similar features is superficial and convergent. In line with other recent studies, we find that Cretaceous ephedroids are extinct stem relatives to the extant clade.

  • 14.
    Ickert-Bond, Stephanie M.
    et al.
    University of Alaska, Fairbanks.
    Rydin, Catarina
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Organismal Biology, Systematic Biology.
    Micromorphology of the seed envelope of Ephedra L. (Gnetales) and its relevance for the timing of evolutionary events2011In: International journal of plant sciences, ISSN 1058-5893, E-ISSN 1537-5315, Vol. 172, no 1, p. 36-48Article in journal (Refereed)
    Abstract [en]

    Micromorphology of the seed envelope of Ephedra (Gnetales) is known to be variable, but variation patternshave never been systematically documented. We test the usefulness of this feature for species determination and subclade delimitation in Ephedra and investigate the relationship of this character to infrageneric evolutionarypatterns. Most species have a basically smooth seed envelope, which in some species appears slightly striate or reticulate due to convex or depressed outer periclinal cell walls. Ephedra rhytidosperma from China and Ephedra torreyana from North America have transverse lamellae formed by the epidermis. A papillate surfaceis found in respective close relatives of these two species. Micromorphology of the seed envelope is generally not useful for species identification or subclade delineation. The amount of variation is low, and intraspecific variation, which in some cases seems to be correlated with hybridization and/or introgression, complicates species recognition. Furthermore, parallel evolution of similar micromorphological patterns in unrelated subclades of Ephedra is evident and cannot be explained by similar seed dispersal mechanisms. The Asian species with transverse lamellae or papillae on the seed are dispersed by frugivores whereas similar American species are anemochoric. Transverse ridges occur in several Early Cretaceous fossil seeds with affinity to Ephedra. However, our results indicate that the resemblance between these fossils and extant taxa with similar features is superficial and convergent. In line with other recent studies, we find that Cretaceous ephedroids are extinct stem relatives to the extant clade.

  • 15.
    Julia Piovan, Maria
    et al.
    Consejo Nacl Invest Cient & Tecn, Argentina.; Justus Liebig Univ Giessen, Germany..
    Pratolongo, Paula
    Consejo Nacl Invest Cient & Tecn, Argentina.; Univ Nacl Sur, Argentina.
    Donath, Tobias W.
    Univ Kiel, Germany.
    Loydi, Alejandro
    Univ Nacl Sur, Argentina.; Consejo Nacl Invest Cient & Tecn, Argentina.
    Eckstein, Rolf Lutz
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Environmental and Life Sciences (from 2013).
    Germination Response to Osmotic Potential, Osmotic Agents, and Temperature of Five Halophytes Occurring along a Salinity Gradient2019In: International journal of plant sciences, ISSN 1058-5893, E-ISSN 1537-5315, Vol. 180, no 4, p. 345-355Article in journal (Refereed)
    Abstract [en]

    Premise of research. Halophyte species grow where salt concentrations are high. Still, their germination may be affected by salts, either by creating an osmotic potential that prevents water uptake or by dissociating in ions that can cause different grades of toxicity. With the increase of salinized areas, it becomes important to understand the behavior of these species. Methodology. We studied how the germination of five halophyte species that occur along a salinity gradient in the Bahia Blanca coastal zone, Atriplex undulata, Cyclolepis genistoides, Allenrolfea patagonica, Sarcocornia perennis, and Heterostachys ritteriana, responds to variations in osmotic agents, osmotic potential, and temperature. Seeds were exposed to different osmotic potentials using NaCl (neutral salt), Na2CO3 (alkaline salt), and mannitol solutions in a germination chamber experiment. Germination was recorded during 42 d. Germination percentage, mean germination time, and synchrony were calculated. Pivotal results. Our experimental results showed that for the five halophyte species under study, germination was mostly driven by osmotic potentials and osmotic agents. At high osmotic potential, the germination response did not differ significantly from controls, except for Allenrolfea and Cyclolepis, which showed lower germination when treated with Na2CO3. Low osmotic potentials and Na2CO3 were detrimental to germination, reflected by lower germination percentages, higher mean germination times, and lower synchrony. Conclusions. In general, the response to the alkaline salt was more negative than that to the neutral salt or mannitol, regardless of the species. Each species showed a different response to the salts under study, and this response matched well with the distribution of species along the salinity gradient observed in the field.

  • 16.
    Kao, Tzu-Tong
    et al.
    Duke Univ, Dept Biol, Durham, NC 27708 USA..
    Pryer, Kathleen M.
    Duke Univ, Dept Biol, Durham, NC 27708 USA..
    Turner, Melvin D.
    Duke Univ, Dept Biol, Durham, NC 27708 USA..
    White, Richard A.
    Duke Univ, Dept Biol, Durham, NC 27708 USA..
    Korall, Petra
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Organismal Biology, Systematic Biology.
    Origins of the Endemic Scaly Tree Ferns on the Galapagos and Cocos Islands2015In: International journal of plant sciences, ISSN 1058-5893, E-ISSN 1537-5315, Vol. 176, no 9, p. 869-879Article in journal (Refereed)
    Abstract [en]

    Premise of research.Successful long-distance dispersal is rarely observed in scaly tree ferns (Cyatheaceae). Nevertheless, recent molecular evidence has suggested that the four endemic scaly tree ferns on the Galapagos Archipelago (Cyathea weatherbyana) and Cocos Island (Cyathea alfonsiana, Cyathea nesiotica, and Cyathea notabilis), two oceanic island groups west of Central and northern South America, probably each originated from different mainland America ancestors. However, the phylogenetic relationships inferred among these endemics and their mainland relatives have been unclear. This study is aimed at better resolving the relationships and tracing the origins of these island endemics.Methodology.Five plastid regions from 35 Cyathea species were analyzed to reconstruct phylogenetic relationships using parsimony, likelihood, and Bayesian approaches. We also estimated divergence times of these species, and our chronogram was used to reconstruct their biogeographical range history.Pivotal results.Our well-resolved phylogenetic tree of Cyathea, which is in agreement with previous studies, shows that when the four Galapagos and Cocos endemics are included, they each belong to separate subclades. Our biogeographical study suggests that the four endemics originated from independent colonization events from mainland America and that there was no dispersal of Cyathea between the island groups. We reveal more detailed relationships among the endemics and their respective close mainland relatives; some of these relationships differ from previous studies. Our findings are corroborated by new morphological data from ongoing stem anatomy studies.Conclusions.The four scaly tree ferns endemic to the Galapagos and Cocos Islands each did indeed originate as independent colonization events from separate sources in mainland America, and their closest relatives are identified here.

  • 17.
    Korall, Petra
    et al.
    Department of Botany, Stockholm University, S-106 91 Stockholm, Sweden.
    Kenrick, P
    Therrien, J P
    Phylogeny of selaginellaceae: Evaluation of generic subgeneric relationships based on rbcL gene sequences1999In: International journal of plant sciences, ISSN 1058-5893, E-ISSN 1537-5315, Vol. 160, no 3, p. 585-594Article in journal (Refereed)
    Abstract [en]

    A cladistic analysis based on rbcL gene sequences from a representative sample of 18 species yields three most parsimonious trees that strongly support monophyly of Selaginellaceae. Within Selaginellaceae, the morphologically distinctive subgenus Selaginella is resolved as sister group to a clade composed of all other species, here termed the rhizophoric clade. In the rhizophoric clade, subgenus Stachygynandrum is paraphyletic to subgenera Ericetorum, Tetragonostachys, and Heterostachys. Monophyly of Ericetorum and Tetragonostachys is strongly corroborated. Results support a close relationship between "resurrection plants" in Stachygynandrum and the mat-forming or tufted drought-tolerant species of Tetragonostachys, indicating a common origin of xerophytism in these groups. A close relationship for all isophyllous species, as hypothesized in many classifications, is not supported by the rbcL data. Leaf isophylly and reduction in Ericetorum and Tetragonostachys most probably represent independent reversals of the marked anisophyllous condition in Stachygynandrum, Leaf reduction is one of a suite of characters that may have evolved in response to seasonal drought.

  • 18.
    Krouchi, F.
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Evolution, Genomics and Systematics, Evolutionary Functional Genomics.
    Gustavsson, S.
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Evolution, Genomics and Systematics, Evolutionary Functional Genomics.
    Sjödin, P.
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Evolution, Genomics and Systematics, Evolutionary Functional Genomics.
    Kruskopf-Osterberg, M.
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Evolution, Genomics and Systematics, Evolutionary Functional Genomics.
    Lagercrantz, U.
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Evolution, Genomics and Systematics, Evolutionary Functional Genomics.
    Lascoux, M.
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Evolution, Genomics and Systematics, Evolutionary Functional Genomics.
    Association between COL1 and Flowering Time in Brassica nigra: Replication, Validation, and Genotypic Disequilibrium2008In: International journal of plant sciences, ISSN 1058-5893, E-ISSN 1537-5315, Vol. 169, no 9, p. 1229-1237Article in journal (Refereed)
    Abstract [en]

    Previously we showed in a limited set of populations that polymorphism at a biallelic indel, Ind2, located within the BniCOL1 gene of Brassica nigra (Bni), was associated with variation in flowering time. Plants that were homozygotes for the short allele flowered early, whereas homozygotes for the long allele flowered late, and the heterozygotes were intermediate. We genotyped individuals from 24 populations that were representative of the current distribution of B. nigra at Ind2 as well as at four adjacent polymorphisms, and we assessed the relationship between polymorphism at these markers and variation in flowering time. The 24 populations comprise populations for which a significant association was previously observed, hence allowing independent replication. Other populations did not overlap with those studied initially and therefore allow validation of the previous results. The presence of a significant relationship between polymorphism at Ind2 and flowering time variation was replicated, but we mostly failed to validate the relationship. Genotypic disequilibrium around Ind2 was extensive, and consequently, polymorphism at markers located in the intergenic space between BniCOL1 and BniCOa was also associated with flowering time in the same populations. All populations from India and Ethiopia had limited polymorphism at all five loci and were fixed for the short allele at Ind2, and all but one flowered early. Our data confirm the involvement of this genomic area in the control of flowering time, but inconsistent results in some of the populations suggest that the relationship between polymorphism in the BniCOL1-BniCOa genomic area and flowering time is not a simple one.

  • 19.
    Källersjö, Mari
    et al.
    Naturhistoriska Riksmuseet, Stockholm.
    Ståhl, Bertil
    Gotland University, Department of Biology.
    Phylogeny of Theophrastaceae (Ericales s. lat.)2003In: International journal of plant sciences, ISSN 1058-5893, E-ISSN 1537-5315, Vol. 164, no 4, p. 579-591Article in journal (Refereed)
    Abstract [en]

    Morphological traits and sequences from two chloroplast genes, ndhF and trnL-F (intron, 3' exon, and spacer), have been used to investigate relationships in the Ericalean family Theophrastaceae. A total evidence parsimony analysis shows that the herbaceous genus Samolus is sister to all other Theophrastaceae. The latter are in turn divided into two major groups, one with Theophrasta, Neomezia, and Clavija and the other with Deherainia, Votschia, and Jacquinia. The representatives of Jacquinia are found in two separate well-supported clades, one consisting of the white-flowered species and the other of the mostly orange-red-flowered species, together with J. paludicola and J. longifolia, two aberrant species with whitish yellow flowers. Deherainia and Votschia group with the latter clade, which makes Jacquinia paraphyletic. We propose that J. paludicola and J. longifolia, together with the orange-red-flowered Jacquinia, be recognized as a separate genus, Bonellia. The sister taxa Theophrasta and Neomezia are confined to Hispaniola and Cuba, respectively. Within Clavija, which is the sister group of Theophrasta-Neomezia, the only Antillean species, Clavija domingensis, is sister to all other species occurring in South and Central America. With the splitting of Jacquinia, Jacquinia s. str. is composed of species occurring in the Caribbean, which are mostly confined to the Greater Antilles, whereas Bonellia is composed of a mixture of Caribbean, Central American, and South American species.

  • 20.
    Larsén, Eva
    et al.
    Stockholm University, Faculty of Science, Department of Ecology, Environment and Plant Sciences.
    Rydin, Catarina
    Stockholm University, Faculty of Science, Department of Ecology, Environment and Plant Sciences.
    DISENTANGLING THE PHYLOGENY OF ISOETES (ISOETALES), USING NUCLEAR AND PLASTID DATA2016In: International journal of plant sciences, ISSN 1058-5893, E-ISSN 1537-5315, Vol. 177, no 2, p. 157-174Article in journal (Refereed)
    Abstract [en]

    Premise of research. The heterosporous lycopsids of Isoetes show limited morphological and genetic variation despite a worldwide distribution and the ancient origin of the lineage. Here major relationships within the genus are clarified, using a substantially larger sampling of species than in previous studies. A first assessment of divergence times of clades is made, and the implications for dispersal mechanisms and biogeographic distribution patterns are discussed. Methodology. On the basis of sequences from three gene regions and 109 specimens representing 74 species of Isoetes, phylogeny and node ages were estimated using parsimony and Bayesian inference. Pivotal results. Three rooting approaches (outgroup analysis, midpoint rooting, and clock rooting) coherently resolved a diverse clade containing species from South Africa, India, Australia, and South America (clade A) as sister to remaining Isoetes. Analysis of divergence times of clades yielded a median age of the crown group of 147 million years ago (mya) using a birth-death tree prior and 165 mya using a Yule tree prior. Clade A was dated to 111 or 125 mya, respectively. While the earliest divergences in Isoetes appear readily explained by ancient vicariance, patterns in younger clades are consistent with dispersal processes, sometimes over long distances. Isoetes andicola (Amstutz) L.D. Gomez, once hypothesized to represent a separate lineage and assigned to the genus Stylites, is here included in a phylogenetic study for the first time. It is closely related to some other South American species, despite its peculiar morphology with a dichotomizing stem. Conclusions. Despite limited intrageneric variation at the molecular and morphological levels, node ages as well as species composition (phylogeny) indicate a Mesozoic origin of the extant clade. Biogeographic patterns appear complicated and intriguing but need more research. Tuberculate megaspore ornamentation (sensu Pfeiffer) is ancestral in the genus, as indicated by current knowledge. Other megaspore patterns appear restricted to two subclades.

  • 21.
    Manns, Ulrika
    et al.
    Stockholm University, Faculty of Science, Department of Botany.
    Anderberg, Arne
    Molecular phylogeny of Anagallis (Myrsinaceae) based on ITS trnL-F and ndhF sequence data.2005In: International journal of plant sciences, ISSN 1058-5893, E-ISSN 1537-5315, Vol. 166, no 6, p. 1019-1028Article in journal (Refereed)
    Abstract [en]

    The phylogeny of Anagallis was elucidated by analysis of sequences from nuclear ribosomal ITS and two chloroplast regions, ndhF and trnL-F. The study included 20 species from the genus Anagallis; two species each of the three small genera Asterolinon, Pelletiera, and Trientalis; and 21 Lysimachia species. The result of a combined analysis using all sequences supports an Anagallis clade that also includes Asterolinon and Pelletiera as well as two Lysimachia species, Lysimachia nemorum and Lysimachia serpyllifolia, making Anagallis paraphyletic in its present circumscription. The clade was not found when analyzing separate data set. The result contradicts earlier studies that indicate a distant relationship between Anagallis s.str. and Anagallis minima (Centunculus) and a close relationship between Lysimachia nemorum, Lysimachia nummularia, and Lysimachia punctata. We also found strong support for a large monophyletic group of Lysimachia species, including the monotypis genus Glaux, and for a basal placement of Lysimachia ciliata and Lysimacha quadrifolia in the tribe.

  • 22.
    Manns, Ulrika
    et al.
    Stockholm University, Faculty of Science, Department of Botany. Stockholm University, Faculty of Science, The Bergius Botanical Garden Museum.
    Wikström, Niklas
    Stockholm University, Faculty of Science, Department of Botany. Stockholm University, Faculty of Science, The Bergius Botanical Garden Museum.
    Taylor, Charlotte M.
    Bremer, Birgitta
    Stockholm University, Faculty of Science, Department of Botany. Stockholm University, Faculty of Science, The Bergius Botanical Garden Museum.
    HISTORICAL BIOGEOGRAPHY OF THE PREDOMINANTLY NEOTROPICAL SUBFAMILY CINCHONOIDEAE (RUBIACEAE): INTO OR OUT OF AMERICA?2012In: International journal of plant sciences, ISSN 1058-5893, E-ISSN 1537-5315, Vol. 173, no 3, p. 261-289Article in journal (Refereed)
    Abstract [en]

    The Rubiaceae is the fifth largest plant family and is found on all continents, mostly in (sub-)tropical regions. Despite a large representation of Rubiaceae in the Paleotropics, the subfamily Cinchonoideae has its primary distribution in the Neotropics. Within the Cinchonoideae only two tribes, Naucleeae and Hymenodictyeae, have Paleotropical centers of distribution. In this study, we used information from five chloroplast DNA markers and fossil data to investigate when the subfamily was established in the Neotropics as well as major subsequent dispersal events within and out of the Neotropics and within the Paleotropics. Our results show that the ancestor of Cinchonoideae and its sister, Ixoroideae, was present in South America during the Late Cretaceous. Dispersal to Central America was estimated to occur during the Early Paleocene, and subsequent dispersals to the Caribbean islands occurred during the Oligocene-Miocene. The ancestor of Naucleeae and Hymenodictyeae dispersed to the Paleotropics no later than the Eocene, and the findings of fossils of Cephalanthus in Europe and western Siberia support its presence in the boreotropical forests. Long-distance, trans-Pacific dispersal during the Miocene was indicated for the remaining Paleotropical Cinchonoideae.

  • 23.
    McLoughlin, Stephen
    et al.
    Swedish Museum of Natural History, Department of Paleobiology.
    Maksimenko, Anton
    Australian Synchrotron.
    Mays, Chris
    Swedish Museum of Natural History, Department of Paleobiology.
    A new high-paleolatitude late Permian permineralized peat flora from the Sydney Basin, Australia2019In: International journal of plant sciences, ISSN 1058-5893, E-ISSN 1537-5315, Vol. 180, p. 513-539Article in journal (Refereed)
    Abstract [en]

    Premise of research. Permineralized peats are prized for hosting three-dimensionally preserved plant remains that provide insights into fossil plant anatomy and the composition of coal-forming ecosystems. A new record of siliceous permineralized peat is documented from a Lopingian-aged (upper Permian) strata from the southern Sydney Basin. It represents the fifth Permian permineralized peat identified from eastern Australia.

    Methodology. The single permineralized peat block was cut into smaller blocks, and both cellulose acetate peels and standard thin sections were prepared for study using transmitted light microscopy. Quantitative analysis of the peat was carried out using point counts perpendicular to bedding. One block examined using synchrotron X-ray computed tomography (CT) revealed the three-dimensional anatomy of abundant fossil seeds.

    Pivotal results. The peat contains a plant assemblage dominated by glossopterid leaves, seeds, and axes; although degraded, probable pteridophyte remains represent a significant subsidiary component of the assemblage. A new leaf form (Glossopteris thirroulensis McLoughlin et Mays sp. nov.) and a new type of seed (Illawarraspermum ovatum McLoughlin et Mays gen. et sp. nov.) are described. Leaf-, wood/seed-, and fine detritus-rich organic microfacies with gradational boundaries are evident within the peat.

    Conclusions. Regular growth rings in the small permineralized axes, together with the occurrence of autumnal mats of glossopterid leaves, signify a strongly seasonal climate. The presence of abundant charcoal in the peat indicates that fire was a significant influence on the high-paleolatitude mire ecosystem. Differentiation of organic microfacies within the peat profile indicates subtle variation in the contribution of plant components to the peat through time. The absence of mineral grains in thin section and CT, together with the presence of authigenic sulfides, indicates accumulation of organic matter in a stagnant mire away from the influence of clastic input.

  • 24.
    Pott, C
    Swedish Museum of Natural History, Department of Paleobiology.
    A revision of Wielandiella angustifolia – a shrub-sized bennettite from the Rhaetian–Hettangian of Scania, Sweden, and Jameson Land, Greenland2014In: International journal of plant sciences, ISSN 1058-5893, E-ISSN 1537-5315, Vol. 201, p. 75-105Article in journal (Refereed)
  • 25.
    Pott, Christian
    Swedish Museum of Natural History, Department of Paleobiology.
    Westersheimia pramelreuthensis from the Carnian (Upper Triassic) of Lunz, Austria: More evidence for a unitegmic seed coat in early Bennettitales2016In: International journal of plant sciences, ISSN 1058-5893, E-ISSN 1537-5315, Vol. 177, p. 771-791Article in journal (Refereed)
    Abstract [en]

    Premise of research. Isolated ovules and dispersed seeds have been obtained from bulk macerations of carbonaceousshales bearing fossil plants from the Carnian (Upper Triassic) flora of Lunz am See, Austria. Throughcuticle analysis, these well-preserved specimens were identified as ovules, interseminal scales, and seeds of Westersheimiapramelreuthensis, a peculiar bennettitalean ovuliferous organ. The preservation of several cuticularlayers enables for interpretation of the architecture of the ovules and seeds.Methodology. The excellently preserved plant fossils were investigated using LM and epifluorescence microscopyof cuticles. For comparison, the architecture of ovules and seeds of bennettitalean reproductive organsfrom Scania (Sweden), Jameson Land (Greenland), and Yorkshire (United Kingdom) were reevaluated.Pivotal results. The preserved layers indicate that the nucellus is surrounded by an integument, whose apicalend constitutes the micropyle. The single integument constitutes the monolayered seed coat in Westersheimia.The ovules and seeds are surrounded by interseminal scales. Of the latter, the cuticle is preserved that abutsthe ovule-seed surface, together with portions of the interseminal scale heads. The seeds provide additional informationon the cuticles of the nucellus or embryo.Conclusions. Studies of bennettitalean reproductive organs from Scania (Sweden), Jameson Land (Greenland),and Yorkshire (United Kingdom) facilitated reevaluation of the disputed architecture of bennettitalean seeds.The findings clearly indicate that early bennettitalean seeds can be interpreted as unitegmic.

  • 26.
    Pott, Christian
    et al.
    Swedish Museum of Natural History, Department of Paleobiology.
    Axsmith, Brian
    Department of Biology, University of South Alabama, Mobile, Alabama 36688, USA.
    Williamsonia carolinensis sp. nov. and associated Eoginkgoites foliage from the Upper Triassic Pekin Formation: Implications for early evolution in Williamsoniaceae (Bennettitales)2015In: International journal of plant sciences, ISSN 1058-5893, E-ISSN 1537-5315, Vol. 176, p. 174-185Article in journal (Refereed)
    Abstract [en]

    Premise of research. Few reproductive organs unequivocally attributable to the important but enigmatic Mesozoic seed plant order Bennettitales have been described from the Triassic of all of North America outside of Greenland. Here, the first ovulate reproductive organs (gynoecia) of the group from the Upper Triassic of eastern North America are described and assigned to a proposed new species, Williamsonia carolinensis, of the family Williamsoniaceae.

    Methodology. The excellently preserved plant fossils were investigated using cuticular analysis and light, fluorescence, and scanning electron microscopy.

    Pivotal results. The description is based on 10 specimens from the Late Triassic (Carnian) Pekin Formation of North Carolina. They are interpreted as representing progressive developmental stages. Williamsonia carolinensis lacks a corona (sterile apical projection of the receptacle) and bracts subtending the receptacle. The lack of bracts is particularly unusual and appears to be the original condition and not apreservation artifact based on their absence even on immature specimens. The two largest specimens, interpreted as mature gynoecia, occur together on the same slab in exclusive association with the unusual bennettitalean leaf Eoginkgoites, suggesting that these organs were produced by the same parent plant species.

    Conclusions. The unique features of W. carolinensis, along with the probable affinity with Eoginkgoites foliage, expands the known diversity of the Williamsoniaceae and supports previous suggestions of remarkably high levels of morphological disparity in the earliest history of the Bennettitales.

  • 27.
    Pott, Christian
    et al.
    Swedish Museum of Natural History, Department of Paleobiology.
    Van der Burgh, J
    Van Konijnenburg-van Cittert, JHA
    New ginkgophytes from the Upper Triassic–Lower Cretaceous of Spitsbergen and Edgeøya (Svalbard, Arctic Norway): The history of Ginkgoales on Svalbard.2016In: International journal of plant sciences, ISSN 1058-5893, E-ISSN 1537-5315, Vol. 177, no 2, p. 175-197, article id 10.1086/684194Article in journal (Refereed)
    Abstract [en]

    Premise of research. During the ongoing investigation of Upper Triassic–Lower Cretaceous plant macrofossilsfrom Svalbard, Norway, some ginkgoalean leaf fossils were found from Carnian and Aptian deposits ofSpitsbergen and Edgeøya that represent newginkgophyte species. One newspecies is described as Baiera aquiloniasp. nov., and one ginkgophyte leaf is assigned to Ginkgoites sp. Along with the description of the new material,an overview of the presence and distribution of ginkgophytes in the high-latitude ecosystems of Svalbard throughtime is provided.Methodology. The plant macrofossils have been analyzed with transmitted-light and epifluorescence microscopy.Attempts to isolate cuticles were made.Pivotal results. The investigation resulted in the description of one species new to science, Baiera aquiloniasp. nov., and one specimen assigned to Ginkgoites sp. The presence of ginkgophytes on Svalbard changed significantlythrough time: periods of dominance and wide distribution interchanged with periods of very lowdiversity and abundance.Conclusions. Ginkgophytes were thriving in Svalbard, which was already located above 607N by the Carnian,from the Late Triassic to the Cenozoic in varying abundance and were finally extirpated, probably as a result ofdramatic climatic changes at the end of the Paleogene

  • 28.
    Pott, Christian
    et al.
    Swedish Museum of Natural History, Department of Paleobiology.
    Van der Burgh, Johan
    Van Konijnenburg-van Cittert, Johanna HA
    NEW GINKGOPHYTES FROM THE UPPER TRIASSIC–LOWER CRETACEOUS OF SPITSBERGEN AND EDGEØYA (SVALBARD, ARCTIC NORWAY):THE HISTORY OF GINKGOALES ON SVALBARD2016In: International journal of plant sciences, ISSN 1058-5893, E-ISSN 1537-5315, Vol. 177, no 2, p. 175-197Article in journal (Refereed)
    Abstract [en]

    Premise of research. During the ongoing investigation of Upper Triassic–Lower Cretaceous plant macrofossilsfrom Svalbard, Norway, some ginkgoalean leaf fossils were found from Carnian and Aptian deposits ofSpitsbergen and Edgeøya that represent newginkgophyte species. One newspecies is described as Baiera aquiloniasp. nov., and one ginkgophyte leaf is assigned to Ginkgoites sp. Along with the description of the new material,an overview of the presence and distribution of ginkgophytes in the high-latitude ecosystems of Svalbard throughtime is provided.Methodology. The plant macrofossils have been analyzed with transmitted-light and epifluorescence microscopy.Attempts to isolate cuticles were made.Pivotal results. The investigation resulted in the description of one species new to science, Baiera aquiloniasp. nov., and one specimen assigned to Ginkgoites sp. The presence of ginkgophytes on Svalbard changed significantlythrough time: periods of dominance and wide distribution interchanged with periods of very lowdiversity and abundance.Conclusions. Ginkgophytes were thriving in Svalbard, which was already located above 607N by the Carnian,from the Late Triassic to the Cenozoic in varying abundance and were finally extirpated, probably as a result ofdramatic climatic changes at the end of the Paleogene.

  • 29.
    Ramula, Satu
    et al.
    Södertörn University, School of Life Sciences.
    Toivonen, Eija
    University of Turku, Turku, Finland.
    Mutikainen, Pia
    Universtiy of Oulu, Oulu, Finland.
    Demographic consequences of pollen limitation and inbreeding depression in a gynodioecious herb2007In: International journal of plant sciences, ISSN 1058-5893, E-ISSN 1537-5315, Vol. 168, no 4, p. 443-453Article in journal (Refereed)
    Abstract [en]

    In a gynodioecious plant population, where female and hermaphroditic plants co- occur, females must produce more seeds or better- quality offspring than hermaphrodites to be maintained. Further, differences in the magnitude of pollen limitation and inbreeding depression between females and hermaphrodites may affect the relative fitness of the gender morphs and consequently population dynamics. We integrated demographic data into data on pollen limitation and inbreeding depression in a gynodioecious herb. Using a matrix model approach, we then examined the effects of pollen limitation and inbreeding depression on population growth rate and sex ratio. Hermaphrodites tended to contribute more to population growth rates than females. Because of the insensitivity of population growth rates to variation in annual fecundity, pollen limitation of either females or hermaphrodites had a negligible effect on population sex ratio. Inbreeding depression expressed simultaneously in three fitness components of the offspring produced by hermaphrodites reduced stochastic population growth rate and increased female frequency. Given that population growth rates are insensitive to fecundity transitions and that hermaphrodites have moderate selfing rates, our results suggest that inbreeding depression plays a larger role in the maintenance of females in gynodioecious populations than pollen limitation.

  • 30.
    Rydin, Catarina
    et al.
    University of Zürich, Institute of Systematic Botany.
    Korall, Petra
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Evolution, Genomics and Systematics, Systematic Biology.
    Evolutionary relationships in Ephedra (Gnetales), with implications for seed plant phylogeny2009In: International journal of plant sciences, ISSN 1058-5893, E-ISSN 1537-5315, Vol. 170, no 8, p. 1031-1043Article in journal (Refereed)
    Abstract [en]

    Evolutionary relationships in Ephedra are difficult to resolve, mainly  because there are few informative characters in investigated loci and   long distances to outgroups. We address these problems by using a large   data set that includes information from seven plastid and nuclear loci   and 204 vascular plants. The deepest divergences in Ephedra are weakly   supported and differ by analytical method, but they indicate a basal   grade of species distributed in the Mediterranean area. New World   species are monophyletic, with a South American clade possibly nested   within a North American clade. A mainly Asian clade comprises several   well-supported subgroups, of which some are endemic to restricted   geographic regions in East or Central Asia; others have a broad   distribution that may extend into Europe (E. distachya, E. major)   and/or Africa (E. pachyclada-E. somalensis). Ephedra laristanica and E.   somalensis are nested within other species, whereas the recognition of   E. milleri as a separate species is supported. Our results provide   another example of how exceptionally difficult it is to disentangle the   early divergences of seed plants. Bayesian analysis strongly supports   the "gnetifer'' hypothesis, a result rarely found in the literature,   but it conflicts with our results from only chloroplast data   ("gne-cup'') and with results of most maximum parsimony analyses   ("Gnetales sister'').

  • 31.
    Schoenenberger, Juerg
    Stockholm University, Faculty of Science, Department of Botany.
    Comparative floral structure and systematics of fouquieriaceae and polemoniaceae (ericales)2009In: International journal of plant sciences, ISSN 1058-5893, E-ISSN 1537-5315, Vol. 170, no 9, p. 1132-1167Article, review/survey (Refereed)
    Abstract [en]

    Floral morphology, anatomy, and histology are comparatively studied in Fouquieriaceae and Polemoniaceae, and previous studies are reviewed. In recent molecular phylogenetic analyses, the two families form a strongly supported clade within the asterid order Ericales, while they were generally placed far from each other in premolecular classifications. This study documents unexpectedly diverse floral features for Polemoniaceae, including various corolla aestivation patterns, different types of anther attachment and anther morphology, as well as two types of nectary structure. Prominent features shared by the two families include determinate-terminal inflorescences, hyaline sepal margins, similar patterns of floral vasculature, late sympetalous corolla development, similar degrees of sympetaly, sterile connective protrusions, short thecal septa, endothecium-like cells in the connective, trimery in the gynoecium, a stylar canal, parietal, and axile and placentation in the same ovary, similar patterns of ovule arrangement and ovule orientation, distally curved micropylar canals, mesophyll-type nectaries with stomata, winged seeds, and seed coat epidermal cells with helical or annular wall thickenings. Several of these features represent potential synapomorphies for the clade with Fouquieriaceae and Polemoniaceae. In addition, potential synapomorphies are also identified for the individual families. While the results of this investigation further support the close relationship of Polemoniaceae and Fouquieriaceae, they also emphasize that it is necessary to abandon preconceptions about the ""systematic importance"" of certain characters that turn out to be more homoplasious than previously thought.

  • 32.
    Sletvold, Nina
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Genetics, Plant Ecology and Evolution.
    The Context Dependence of Pollinator-Mediated Selection in Natural Populations2019In: International journal of plant sciences, ISSN 1058-5893, E-ISSN 1537-5315, Vol. 180, no 9, p. 934-943Article in journal (Refereed)
    Abstract [en]

    Pollinator-mediated selection to a large extent shapes angiosperm floral diversity, but clearly not in isolation. To understand how selection by pollinators interacts with other selective factors and depends on environmental context, studies that address multiple selective agents are necessary. Here, I illustrate how antagonistic interactions, community context, and resource availability may influence selection on floral traits. I discuss approaches to quantify the context dependence of pollinator-mediated selection, emphasizing experimental studies that manipulate pollination regime in combination with other putative selective factors. I also discuss how context dependence may differ between floral traits that affect pollinator attraction versus pollination efficiency. Finally, I suggest some areas where important progress can be made. A better understanding of the context dependence of pollinator-mediated selection is essential to predict when, where, and how environmental change will alter selection on floral traits.

  • 33. Sletvold, Nina
    et al.
    Ågren, Jon
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Genetics. Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Evolution, Ecological Botany.
    Pollinator-Mediated Selection on Floral Display and Spur Length in the Orchid Gymnadenia conopsea2010In: International journal of plant sciences, ISSN 1058-5893, E-ISSN 1537-5315, Vol. 171, no 9, p. 999-1009Article in journal (Refereed)
    Abstract [en]

    Floral diversification and specialization are thought to be driven largely by interactions with pollinators, but the extent to which current selection on floral traits is mediated by pollinators has rarely been determined experimentally. We documented selection through female function on floral traits in two populations of the rewarding orchid Gymnadenia conopsea in two years and quantified pollinator-mediated selection (Delta beta(poll)) by subtracting estimates of selection gradients for plants receiving supplemental hand pollination from estimates obtained for open-pollinated control plants. There was directional selection for taller plants, more flowers, larger corollas, and longer spurs in the study populations. Pollinator-mediated selection ranged from weak to moderately strong (Delta beta(poll), range -0.01-0.21, median 0.08). All observed selection on spur length could be attributed to interactions with pollinators, while the proportion of observed selection on plant height (0%-77%), number of flowers (13%-42%), and corolla size (13%-97%) caused by pollinators varied among populations and years. Our results demonstrate that pollinators can mediate selection on both traits likely to be involved in pollinator attraction and traits affecting pollination efficiency. They further show that spatiotemporal variation in the strength of pollinator-mediated selection can contribute substantially to differences in selection between years and populations.

  • 34.
    Thompson, Stacey Lee
    et al.
    Institut de recherche en biologie végétale, Université de Montréal, Canada.
    Choe, Gina
    Ritland, Kermit
    Whitton, Jeannette
    Cryptic sex within male-sterile polyploid populations of the Easter daisy, Townsendia hookeri2008In: International journal of plant sciences, ISSN 1058-5893, E-ISSN 1537-5315, Vol. 169, no 1, p. 183-193Article in journal (Refereed)
    Abstract [en]

    After a transition from sexuality to asexuality, the evolutionary dynamics in apomictic lineages will largely depend on the frequency of recombination. We evaluated the presence and extent of asexuality and recombination within populations of the Easter daisy, Townsendia hookeri, from the Yukon Territory, Canada. Amplified fragment-length polymorphism (AFLP) fingerprints were used to genotype 78 individuals from four populations. Multilocus AFLP genotypes from each population were subjected to four tests for deviations from free recombination among loci, and the long-term frequency of sexuality was estimated for each population with a novel procedure. In addition, a sample of individuals was surveyed for genome size using flow cytometry, and pollen was assayed for male fertility. One male-fertile, diploid population showed evidence of rampant recombination. Two male-sterile populations (i.e., with aborted anthers) were tetraploid and asexual. The remaining population was male-sterile and included both triploids and tetraploids. Evidence of both sexuality and asexuality was uncovered in this mixed-ploidy population, at an equilibrium rate of approximately three sexual events every two generations. The presence and extent of sexuality differed with ploidy, while cryptic sex was uncovered within a morphologically asexual population, thus reinforcing the power of genome surveys to assess reproductive dynamics at the limit of a plant's geographical range.

  • 35.
    Thureborn, Olle
    et al.
    Stockholm University, Faculty of Science, Department of Ecology, Environment and Plant Sciences.
    Razafimandimbison, Sylvain G.
    Wikström, Niklas
    Stockholm University, Faculty of Science, Department of Ecology, Environment and Plant Sciences. Royal Swedish Academy of Sciences, Sweden.
    Khodabandeh, Anbar
    Stockholm University, Faculty of Science, Department of Ecology, Environment and Plant Sciences. Royal Swedish Academy of Sciences, Sweden.
    Rydin, Catarina
    Stockholm University, Faculty of Science, Department of Ecology, Environment and Plant Sciences. Royal Swedish Academy of Sciences, Sweden.
    Phylogeny of Anthospermeae of the Coffee Family Inferred Using Clock and Nonclock Models2019In: International journal of plant sciences, ISSN 1058-5893, E-ISSN 1537-5315, Vol. 180, no 5, p. 386-402Article in journal (Refereed)
    Abstract [en]

    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 Carpacoce resolved 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.

  • 36. Trift, ida
    et al.
    Lidén, Magnus
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Organismal Biology, Systematic Biology. Uppsala University, Music and Museums, The Linnean Gardens of Uppsala, Botanical Garden.
    Anderberg, Arne A
    Phylogeny and Biogeography of Dionysia (Primulaceae)2004In: International journal of plant sciences, ISSN 1058-5893, E-ISSN 1537-5315, Vol. 165, no 5, p. 845-860Article in journal (Refereed)
    Abstract [en]

    Cladistic analyses using parsimony jackknifing and Bayesian inference were performed to elucidate phylogenetic relationships in the genus Dionysia. DNA sequences from one nuclear DNA region (ITS) and from two chloroplast genome regions (rps16 intron and trnL‐trnF) were used with and without the addition of a morphological character matrix. A total of 43 species from Primulaceae were sequenced, including 39 species of Dionysia. The results strongly suggest that the sister species to the rest of genus Dionysia are Dionysia balsamea and D. hissarica, not D. mira. No section and subsection with more than one species ofDionysia as currently circumscribed appears to be monophyletic. Instead, species often belong to clades corresponding to geographical proximity. Earlier proposed notions of evolutionary trends and geographical migrations in Dionysia are discussed.

  • 37. von Balthazar, Maria
    et al.
    Schoenenberger, Juerg
    Stockholm University, Faculty of Science, Department of Botany.
    Floral Structure and Organization in Platanaceae2009In: International journal of plant sciences, ISSN 1058-5893, E-ISSN 1537-5315, Vol. 170, no 2, p. 210-225Article in journal (Refereed)
    Abstract [en]

    Developing and mature inflorescences and flowers of several representatives of Platanus were studied to clarify various aspects of floral structure and organization. Special attention was given to perianth differentiation. Extant Platanaceae are monoecious with unisexual flowers aggregated into compact, spherical inflorescence heads. Development of hairs in a basipetal direction subdivides the undifferentiated inflorescence surface into floral zones. Development of both male and female flowers of Platanus 3 hispanica begins with the initiation of a perianth whorl. Thereafter, the reproductive organs emerge on the floral apex: stamens in male flowers, staminodes and carpels in female flowers. The last organs to appear in both sexes are the small organs located between perianth and androecium. At anthesis, in both male and female flowers, organs of the first whorl are inconspicuous, scalelike, and only two to three cell layers thick. Alternating with these first thin organs is a whorl of short but fleshy organs. These second-whorl organs are basally united with the stamens, forming a short androecial tube. They also show some structural similarities with stamens. These features support the hypothesis that the second-whorl organs are of androecial (staminodial) origin. This hypothesis is further supported by the fossil record, where, in some taxa, second-whorl organs are particularly similar to stamens, as well as by morphological comparisons with flowers of Proteaceae.

  • 38.
    von Zeipel, Hugo
    et al.
    Mid Sweden University, Faculty of Science, Technology and Media, Department of Natural Sciences.
    Eriksson, Ove
    Stockholm University.
    Fruit removal in the forest herb Actaea spicata depends on local context of fruits sharing the same dispersers2007In: International journal of plant sciences, ISSN 1058-5893, E-ISSN 1537-5315, Vol. 168, no 6, p. 855-860Article in journal (Refereed)
    Abstract [en]

    Heterospecific effects from neighboring plants on fruit removal are rarely examined. In this study we recorded removal of fruits of four species from experimental plots. The main study species, the forest herb Actaea spicata, has berries attractive to rodents. We tested for effects from a larger-scale context (plant abundance) and a smaller scale (number of fruits aggregated including several species with fleshy as well as dry fruits). Fruit removal varied among sites. Fleshy-fruited species removal was correlated within sites. Fruit removal was higher within than outside Actaea populations but was unrelated to plant abundances among existing populations. The small-scale context treatment yielded clear results. Removal of Actaea fruits was higher from large aggregations of fruits, and it was the number of fruits rather than species identity that affected removal. Presence of both fleshy and dry fruits increased removal. This study provides experimental evidence of heterospecific effects on fruit removal, and we conclude that the species included in the study attract the same dispersers and that the small-scale biotic context is important. We suggest the existence of dispersal hot spots related to the fruit presence overlaid by an unexplained variation among sites.

  • 39.
    Wredle, Ulla
    et al.
    Stockholm University, Faculty of Science, Department of Botany.
    Walles, Björn
    Stockholm University, Faculty of Science, Department of Botany.
    The formation of autophagic vacuoles during programmed cell death in the suspensor and endosperm of Vicia fabaIn: International journal of plant sciences, ISSN 1058-5893, E-ISSN 1537-5315Article in journal (Refereed)
  • 40.
    Wredle, Ulla
    et al.
    Stockholm University, Faculty of Science, Department of Botany.
    Walles, Björn
    Hakman, Inger
    Chromoplasts are formed in Vicia faba suspensor cells2000In: International journal of plant sciences, ISSN 1058-5893, E-ISSN 1537-5315, Vol. 161, no 5, p. 713-719Article in journal (Refereed)
    Abstract [en]

    In Vicia faba, the plastids of the suspensor have a structure that is unique for this tissue. Their development was followed from 4 to 15 days after pollination (dap), when the suspensor has started to degenerate. The appearence of the plastids changes from small and rounded to large and more or less amoeboid. A distinct peripheral reticulum and ribosomes are present throughout plastid development. At 11 dap, most plastids have formed one or more prolamellar bodies. After zinc iodide-osmium tetroxide staining, the plastids also show strongly electron-scattering bundles of membrane tubules, sometimes with cross-linking between individual thylakoids. At 13-14 dap, the thylakoid system includes large electron-transparent spaces that are traversed by undulating membranes. Such a structure is characteristic of chromoplasts containing carotenoid crystals. In the light microscope, crystals are seen as bright red inclusions in the plastids.

  • 41.
    Wredle, Ulla
    et al.
    Stockholm University, Faculty of Science, Department of Botany.
    Walles, Björn
    Stockholm University, Faculty of Science, Department of Botany.
    Hakman, Inger
    Stockholm University, Faculty of Science, Department of Botany.
    DNA fragmentaion and nuclear degradation during programmed cell death in the suspensor and endosperm of Vicia faba2001In: International journal of plant sciences, ISSN 1058-5893, E-ISSN 1537-5315, Vol. 162, no 5, p. 1053-1063Article in journal (Refereed)
    Abstract [en]

    In Vicia faba, both the suspensor and the endosperm are short‐lived structures. The aim of this work was to elucidate and compare programmed cell death (PCD) mechanisms in these two ephemeral tissues. To achieve this, we used the TdT‐mediated dUDP fluorescent (FITC) nick end labeling (TUNEL) technique to trace DNA fragmentation and transmission electron microscopy to follow chromosomal and nuclear degradation. The TUNEL experiments demonstrated DNA fragmentation in the endosperm nuclei 13 d after pollination (dap) and in the suspensor at 14 dap. However, the ultrastructural studies did not show any chromosomal degradation in the nuclei of the suspensor or endosperm until 17 dap, indicating that the DNA fragmentation is an initial step in the PCD pathway. We have further documented fundamental differences in the degeneration process of the nuclei of the two tissues. In the suspensor the heterochromatin becomes more condensed during degeneration and disperses to the nuclear periphery as electron‐dense areas. The nucleolus will keep its round and condensed shape for some time before expanding into an irregular body. In the endosperm the heterochromatin is more like a network throughout the nucleus, and the nucleolus will eventually split into pieces scattered inside the heterochromatin. Internal vesicle‐like structures appear in the nuclei of the suspensor at 11–13 dap. However, they might have a communicative function not necessarily related to the cell death. We conclude that both the suspensor and the endosperm go through PCD processes, but the pathways leading to dismantling of the cells do not follow identical routes in the two tissues. DNA fragmentation occurs in intact cells and within an intact nuclear envelope and not in cells that already are damaged. PCD in the endosperm precedes PCD in the suspensor, indicating that they might receive different signals or that the signal triggers different internal death programs in the two tissues.

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