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  • 401.
    Larsson, John
    et al.
    Stockholm University, Faculty of Science, Department of Botany.
    Nylander, Johan
    Natural History Museum, University of Oslo.
    Bergman, Birgitta
    Stockholm University, Faculty of Science, Department of Botany.
    Genome fluctuations in cyanobacteria reflect evolutionary, developmental and adaptive traitsIn: BMC Evolutionary Biology, ISSN 1471-2148, E-ISSN 1471-2148Article in journal (Refereed)
  • 402.
    Larsson, John
    et al.
    Stockholm University, Faculty of Science, Department of Botany.
    Nylander, Johan
    Natural History Museum, University of Oslo.
    Bergman, Birgitta
    Stockholm University, Faculty of Science, Department of Botany.
    Horizontally transferred genes in a cyanobacterial plant symbiont suggest roles in symbiosis maintenanceManuscript (preprint) (Other academic)
  • 403. Lazaro, A.
    et al.
    Mendez, M.
    Stockholm University, Faculty of Science, Department of Botany.
    Variation in sexual expression in the monoecious shrub Buxus balearica at different scales2007In: Plant Biology, ISSN 1435-8603, E-ISSN 1438-8677, Vol. 9, no 6, p. 736-744Article in journal (Refereed)
    Abstract [en]

    Monoecy allows high plasticity in gender expression because the production of separate female and male flowers increases the ability to respond to specific environmental circumstances. We studied variation in sexual expression and its correlates in the monoecious shrub Buxus balearica, for two years, in six populations in the Balearic Islands and four in the Iberian Peninsula. Phenotypic gender varied among populations; while island populations showed slight variations around an average gender, mainland populations showed a broad range of variation in gender among individuals, always biased towards increasing maleness compared with the other populations. Within populations, gender was not related to plant size. Between-year changes were slight and mainly consisted of an increase in relative maleness in the mast year. Reproduction did not affect gender in the next year, as assessed by either observational or experimental methods. Most variation in gender expression occurred among individuals within populations (83.6%), followed by variation among populations (13.6%) and years (2.8%). Our results suggest that male-biased gender at population and plant levels was related to stressful conditions and resource limitation, because: (1) maleness was higher in mainland populations, where summer drought was stronger; (2) maleness increased with elevation; (3) fruit set was positively correlated with femaleness; (4) the percentage of male inflorescences increased over the flowering period; and (5) male inflorescences were preferentially in lower parts of the branch nodes. Higher maleness in mast years, however, could be related to increased male success under synchronic flowering.

  • 404. Lehtilä, Kari
    et al.
    Boalt, Elin
    Stockholm University, Faculty of Science, Department of Botany.
    The use and usefulness of artificial herbivory in plant herbivore studies.2004In: Insects and Ecosystem, 2004, p. 257-275Chapter in book (Other academic)
  • 405. Lehtilä, Kari
    et al.
    Holmén Bränn, Kristina
    Stockholm University, Faculty of Science, Department of Botany.
    Correlated effects of selection for flower size in Raphanus raphanistrum2007In: Canadian Journal of Botany, ISSN 0008-4026, E-ISSN 1480-3305, Vol. 85, no 2, p. 160-166Article in journal (Refereed)
    Abstract [en]

    The evolution of flower size may be constrained by trade-offs between flower size and other plant traits. The aim of this study was to determine how selection on flower size affects both reproductive and vegetative traits. Raphanus raphanistrum L. was used as the study species. Artificial selection for small and large petal size was carried out for two generations. We measured the realized heritability of flower size and recorded flower production, time to flowering, plant size, and seed production in the two selection lines. The realized heritability was h2 = 0.49. Our study, therefore, showed that R.raphanistrum has potential for rapid evolutionary change of floral size. The lines with large flowers produced smaller seeds and started to flower later than the lines with small flowers. There was no trade-off between flower size and flower number, but the lines selected for large flower size had more flowers and a larger plant size than lines selected for small flowers. Estimates of restricted maximum likelihood (REML) analysis of pedigrees also showed that flower size had a positive genetic correlation with start of flowering and plant height.

  • 406.
    Lemessa, Debissa
    Stockholm University, Faculty of Science, Department of Botany.
    Crop pests and Natural Enemies in Agricultural Landscapes in Relation to Spatial Heterogeneity of Wild Trees and Forests2011Report (Other academic)
    Abstract [en]

    The conversion of natural habitat for human use such as, agricultural intensification and others cause the simplification of landscape and loss of biodiversity. The fragmentation of landscape may influence the ecological functions like trophic cascades or predator-prey-primary producer interactions either directly or indirectly. This paper presents the review of the major theories in population regulation, island biogeography, and general concepts in brief and some reports of research findings in trophic cascades, population dynamics of natural enemies in agricultural landscape in both temperate and tropical contexts. The result of the review indicated that the heterogeneity of agricultural landscape (e.g. from simple crop habitat to complex natural habitat) determines not only the cross-edge spillover but also affects the magnitude (abundance), direction of flow and diversity of natural enemies and crop pests. As a result, the efficiency of natural regulation of crop pests in top-down and bottom-up processes may vary accordingly.  Nevertheless, from the literature I have assessed, I would suggest that further empirical research is needed to get a comprehensive understanding concerning the relationship between natural pest regulation functions (top-down and bottom-up mechanisms) and crop pests in agroecosystem both at local and regional scales. This suggestion may be vital mainly in tropical regions context where the high biodiversity is declining rapidly on one hand and where little information is currently available on the other verge.

  • 407. Lenoir, Jonathan
    et al.
    Graae, Bente Jessen
    Aarrestad, Per Arild
    Alsos, Inger Greve
    Armbruster, W. Scott
    Austrheim, Gunnar
    Bergendorff, Claes
    Birks, H. John B.
    Brathen, Kari Anne
    Brunet, Jorg
    Bruun, Hans Henrik
    Dahlberg, Carl Johan
    Stockholm University, Faculty of Science, Department of Botany.
    Decocq, Guillaume
    Diekmann, Martin
    Dynesius, Mats
    Ejrnaes, Rasmus
    Grytnes, John-Arvid
    Hylander, Kristoffer
    Stockholm University, Faculty of Science, Department of Botany.
    Klanderud, Kari
    Luoto, Miska
    Milbau, Ann
    Moora, Mari
    Nygaard, Bettina
    Odland, Arvid
    Ravolainen, Virve Tuulia
    Reinhardt, Stefanie
    Sandvik, Sylvi Marlen
    Schei, Fride Hoistad
    Speed, James David Mervyn
    Tveraabak, Liv Unn
    Vandvik, Vigdis
    Velle, Liv Guri
    Virtanen, Risto
    Zobel, Martin
    Svenning, Jens-Christian
    Local temperatures inferred from plant communities suggest strong spatial buffering of climate warming across Northern Europe2013In: Global Change Biology, ISSN 1354-1013, E-ISSN 1365-2486, Vol. 19, no 5, p. 1470-1481Article in journal (Refereed)
    Abstract [en]

    Recent studies from mountainous areas of small spatial extent (<2500km2) suggest that fine-grained thermal variability over tens or hundreds of metres exceeds much of the climate warming expected for the coming decades. Such variability in temperature provides buffering to mitigate climate-change impacts. Is this local spatial buffering restricted to topographically complex terrains? To answer this, we here study fine-grained thermal variability across a 2500-km wide latitudinal gradient in Northern Europe encompassing a large array of topographic complexities. We first combined plant community data, Ellenberg temperature indicator values, locally measured temperatures (LmT) and globally interpolated temperatures (GiT) in a modelling framework to infer biologically relevant temperature conditions from plant assemblages within <1000-m2 units (community-inferred temperatures: CiT). We then assessed: (1) CiT range (thermal variability) within 1-km2 units; (2) the relationship between CiT range and topographically and geographically derived predictors at 1-km resolution; and (3) whether spatial turnover in CiT is greater than spatial turnover in GiT within 100-km2 units. Ellenberg temperature indicator values in combination with plant assemblages explained 4672% of variation in LmT and 9296% of variation in GiT during the growing season (June, July, August). Growing-season CiT range within 1-km2 units peaked at 6065 degrees N and increased with terrain roughness, averaging 1.97 degrees C (SD=0.84 degrees C) and 2.68 degrees C (SD=1.26 degrees C) within the flattest and roughest units respectively. Complex interactions between topography-related variables and latitude explained 35% of variation in growing-season CiT range when accounting for sampling effort and residual spatial autocorrelation. Spatial turnover in growing-season CiT within 100-km2 units was, on average, 1.8 times greater (0.32 degrees Ckm1) than spatial turnover in growing-season GiT (0.18 degrees Ckm1). We conclude that thermal variability within 1-km2 units strongly increases local spatial buffering of future climate warming across Northern Europe, even in the flattest terrains.

  • 408. Lens, Frederic
    et al.
    Karehed, Jesper
    Stockholm University, Faculty of Science, Department of Botany.
    Baas, Pieter
    Jansen, Steven
    Rabaey, David
    Huysmans, Suzy
    Hamann, Thomas
    Smets, Erik
    The wood anatomy of the polyphyletic Icacinaceae s.l., and their relationships within asterids2008In: Taxon, ISSN 0040-0262, E-ISSN 1996-8175, Vol. 57, no 2, p. 525-552Article, review/survey (Refereed)
    Abstract [en]

    Wood samples from 53 species belonging to 41 genera of the Icacinaceae s.l. are investigated using light and scanning electron microscopy. The traditionally circumscribed leacinaceae fall apart into four segregate families that are clearly nested within asterids, i.e., Icacinaceae s.str. (near or in Garryales), Cardiopteridaceae and Stemonuraceae (both Aquifoliales), and Pennantiaceae (Apiales). From a wood anatomical point of view, these families cannot easily be distinguished from each other. However, some features such as vessel distribution, perforation plate morphology, size and arrangement of vessel pits, fibre wall thickness, and the occurrence of cambial variants can be used to assign various species to one of the four families. The wood structure of the four segregate families is in general agreement with their suggested putative relatives, but the occurrence of lianas versus erect trees and shrubs is a confusing factor in getting clear phylogenetic signal from the wood structure. Maximum parsimony and Bayesian analyses using molecular data and combined anatomical-molecular data show that Icacinaceae s.str. are not monophyletic, and their closest relatives remain unclear. The combined analyses provide moderate support for a clade including Cassinopsis, the Apodytes-group, the Emmotum-group (all Icacinaceae s.str.), and the genus Oncotheca. This clade is situated at the base of lamiids and may be closely related to Garryales. The remaining lineage of Icacinaceae s.str., the Icacina-group represented by many climbing taxa exhibiting cambial variants, is strongly supported and might be sister to the rest of lamiids.

  • 409. Lens, Frederic
    et al.
    Schönenberger, Jürg
    Stockholm University, Faculty of Science, Department of Botany. Systematik.
    Baas, Pieter
    Jansen, Steven
    Smets, Erik
    The role of wood anatomy in phylogeny reconstruction of Ericales2007In: Cladistics, Vol. 23, p. 229-254Article in journal (Refereed)
  • 410.
    Lin, Senjie
    et al.
    Department of Marine Sciences, University of Connecticut, USA.
    Sandh, Gustaf
    Stockholm University, Faculty of Science, Department of Botany.
    Zhang, Huan
    Department of Marine Sciences, University of Connecticut, USA.
    Cheng, Jiujun
    Stockholm University, Faculty of Science, Department of Botany.
    Perkins, Keri
    Department of Marine Sciences, University of Connecticut, USA.
    Bergman, Birgitta
    Stockholm University, Faculty of Science, Department of Botany.
    Carpenter, Edward
    Romberg Tiburon Center, San Francisco State University, USA.
    Two flavodoxin genes in Trichodesmium (Oscillatoriales, Cyanophyceae): Remarkable sequence divergence and possible functional diversification2009In: Journal of Experimental Marine Biology and Ecology, ISSN 0022-0981, E-ISSN 1879-1697, Vol. 371, no 1, p. 93-101Article in journal (Refereed)
    Abstract [en]

    We analyzed flavodoxin gene sequences and transcription patterns in the marine nitrogen-fixing cyanobacterium Trichodesmium Ehrenberg ex Gomont 1892. While a typical cyanobacterial flavodoxin ortholog (fld1) was identified from cultured (strain IMS101) and environmental Trichodesmium by PCR and Southern blot hybridization, a second flavodoxin (fld2) was identified in the genome sequence. BLAST and phylogenetic analyses indicated that the two fld genes were highly divergent: fld1 was most closely related to fld common in cyanobacteria, wheras fld2 formed a distinct cluster with a fld so far only found in the unicellular diazotrophic cyanobacteria Cyanothece and Crocosphaera (in which fld2 was the only fld). The fld2 cluster was more closely allied with a fld in non-cyanobacterial diazotrophs such as Azotobacter and Azoarcus than fld1 in other cyanobacteria. This result suggests different evolutionary history of these two genes. Real-Time RT–PCR analysis on iron-replete and iron-deplete Trichodesmium cultures revealed remarkable diel dynamics in transcription of both flds but surprisingly failed to show induction under iron stress. Addition of nitrate to these cultures depressed nifH and fld2 transcription while elevating the transcription of fld1 in iron-stressed cultures. A positive correlation between fld and nifH transcript abundances was found, which was stronger in the case of fld2 than fld1. Our data suggest that these two flavodoxins in Trichodesmium may be functionally diversified and that use of flavodoxin as an iron stress indicator needs to be validated for each organism with consideration of diel dynamics of gene expression.

  • 411.
    Lindberg, Sylvia
    et al.
    Stockholm University, Faculty of Science, Department of Botany.
    Kader, M Abdul
    Bangladesh Agricultural University.
    Seidel, Thorsten
    University of Bielefeld, Germany.
    Golldack, Dortje
    University of Bielefeld.
    Yemelyanov, Vladislav
    University of St. Petersburg, Russia.
    Sodium sensing induces different changes in freecytosolic calcium concentration and pH in salt-tolerantand -sensitive rice (Oryza sativa) cultivars2007In: Physiologia Plantarum: An International Journal for Plant Biology, ISSN 0031-9317, E-ISSN 1399-3054, Vol. 130, p. 99-111Article in journal (Refereed)
  • 412.
    Lindberg, Sylvia
    et al.
    Stockholm University, Faculty of Science, Department of Botany.
    kader, Md Abdul
    Bangladesh Agricultural University.
    Yemelyanov, Vladislav
    St Petersburg State University.
    Calcium signalling in plant cells under environmental stress2011In: Environmental adaptations and stress tolerance of plants in the era of climate change / [ed] Parvaiz A and Prasad MNV, New york, NY: Springer, 2011, 1, p. 325-360Chapter in book (Refereed)
    Abstract [en]

    A change of intracellular calcium concentration is an early event in a large array of biological processes in plants, such as cell division, polarity, growth and development at normal conditions and under adaptation to abiotic and biotic stresses. This chapter will focus on calcium signaling induced by different types of abiotic stress, such as salt, cold, anoxia, aluminium and heavy metal stresses. A minor part deals with biotic stress signaling. Most investigations, so far, concerned Ca2+ signaling in the cytosol, but the last years also signaling in the nucleus and other cell compartments such as mitochondria, ER and cell wall have been reported. We will compare the specific “signature” of calcium, including duration, amplitude and frequency of the signaling, which is induced by different stresses and is important for a change of the physiological function. Different stores for calcium take part in the signaling under various types of stresses. Of special interest is a comparison of signaling in tolerant and sensitive species and cultivars.

  • 413.
    Lindberg, Sylvia
    et al.
    Stockholm University, Faculty of Science, Department of Botany. växtfysiologi.
    Landberg, Tommy
    Stockholm University, Faculty of Science, Department of Botany. växtfysiologi.
    Greger, Maria
    Stockholm University, Faculty of Science, Department of Botany. växtfysiologi.
    Cadmium uptake and interaction with phytochelatins in wheat protoplasts: Cadmium uptake and interaction with phytochelatins in wheat protoplasts2007In: Plant Physiology and Biochemistry: Plant Physiology and Biochemistry, Vol. 45, no 1, p. 47-53Article in journal (Refereed)
    Abstract [en]

    In order to investigate the role of phytochelatins in short-time uptake of Cd2+ into the cytosol of wheat protoplasts, a new method was

    applied, using fluorescence microscopy and the heavy metal-specific fluorescent dye, 5-nitrobenzothiazole coumarin, BTC-5N. The uptake of Cd2+ into protoplasts from 5- to 7-day-old wheat seedlings (Triticum aestivum, L. cv. Kadett) was lower in protoplasts from seedlings raised in

    the presence of 1 mM CdCl2, than in the absence. Presence of CdCl2 in the cultivation medium increased the content of phytochelatins (PCs) in the protoplasts. When seedlings were raised in the presence of both Cd2+ and buthionine sulfoximine (BSO), an inhibitor of glutathione (GSH) synthesis, only little PC was found in the protoplasts. Pre-treatment with BSO alone did not affect the content of PC, but inhibited that of GSH. The inhibition of GSH was independent of pre-treatment with Cd2+. Unidirectional flux analyses, using 109Cd2+, showed approximately the same uptake pattern of Cd2+ as did the fluorescence experiments showing the cytosolic uptake of Cd2+. Thus, the diminished uptake of Cd2+ into protoplasts from cadmium-pre-treated plants was not depending on PCs. Instead, it is likely that pre-treatment with Cd2+ causes a down-regulation of the short-term Cd2+ uptake, or an up-regulation of the Cd2+ extrusion. Moreover, since addition of Cd2+ to protoplasts from control plants caused a cytosol acidification, it is likely that a Cd2+/H+-antiport mechanism is involved in the extrusion of Cd2+ from these protoplasts.

  • 414.
    Lindborg, Regina
    Stockholm University, Faculty of Science, Department of Botany.
    Land Use Change in Space and Time: implications for plant species conservation in semi-natural grasslands2004Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Land use change has during the last century altered the traditional rural landscape in Sweden, resulting in a major decline in species diversity. Traditional small-scale farming, with a remarkably high small-scale species richness, has changed in favour of rationalized agriculture, and many semi-natural grasslands, i.e. traditionally managed pastures and meadows, have become abandoned. In this thesis I examine how spatio-temporal processes affect plant species in Swedish semi-natural grasslands exposed to habitat degradation as well as recovery (restoration). I also discuss how to conserve plant species associated with semi-natural grasslands.

    In general, species responded slowly to habitat degradation, but quickly to improvement of habitat quality. Population viability analysis (PVA) of the grazing favoured herb Primula farinosa suggested, in contrast to historical records, that populations in abandoned grasslands performed better than populations in traditionally managed grasslands, a result questioning the accuracy of PVAs. Restoration of grasslands counteracted species richness decline and the number of species increased within seven years after restoration. It was possible to recruit grassland species in grazed former arable fields by artificial seed-sowing. This may help to speed up the natural recruitment, which often is low due to dispersal limitations in modern fragmented landscapes.

    Studies at larger regional scales showed century long time-lags in the response of plant species richness to land use change. Species richness was not related to present-day connectivity of grasslands, but positive effects appeared for grassland configuration in 1950s and 1900s. Thus, making conservation guidelines based solely on present-day data may be strongly misleading and under-estimate the actual risk of species loss. To secure long-term survival of species, it is important to focus on processes associated with larger spatial scales. This may benefit natural dynamics at longer time-scales, where abandoned and restored grasslands, together with species-rich semi-natural grasslands, could become natural parts of sustainable landscape management.

  • 415.
    Lindborg, Regina
    Stockholm University, Faculty of Science, Department of Botany.
    Recreating Grasslands in Swedish Rural Landscapes: Effects of Seed Sowing and Management History2006In: Biodiversity and Conservation, ISSN 0960-3115, E-ISSN 1572-9710, Vol. 15, no 3, p. 957-969Article in journal (Refereed)
    Abstract [en]

    Recent loss of plant species richness in Swedish semi-natural grasslands has led to an increase in grassland recreation and restoration. To increase the establishment of declining species favoured by grazing and to re-establish original species richness, seed sowing has been discussed as a conservation tool. In this study, I examined to what extent seed sowing in former arable fields increases species richness and generates a species composition typical of semi-natural grasslands. Six grassland species favoured by grazing (target species) and six generalist species favoured by ceased grazing, were studied in a seed-addition experiment. Four different seed densities were used on four different grassland categories, two grazed former arable fields, one continuously grazed grassland and one abandoned grassland. Target and generalist species emerged in all grassland categories, but seedling emergence was higher in the grazed than in the abandoned grassland. Target species had higher emergence in the two grasslands with the longest grazing continuity. Seedling emergence and frequency of established plants of each target species were positively associated. The largest fraction of seeds germinated at an intermediate sowing density, 20–50 seeds/dm2, suggesting that aggregation of seeds positively affects emergence up to a certain threshold. In conclusion, artificial seed sowing may induce the recreation of typical grassland communities on former arable fields, which may be an important contribution to increase the total grassland area and species richness in the landscape.

  • 416.
    Lindborg, Regina
    et al.
    Stockholm University, Faculty of Science, Department of Systems Ecology.
    Bengtsson, Jan
    Berg, Åke
    Cousins, Sara A.O.
    Stockholm University, Faculty of Science, Department of Botany. Stockholm University, Faculty of Science, Department of Physical Geography and Quaternary Geology.
    Eriksson, Ove
    Stockholm University, Faculty of Science, Department of Botany.
    Gustafsson, Tomas
    Hasund, Knut Per
    Lenoir, Lisette
    Pihlgren, Aina
    Sjödin, Erik
    Stenseke, Marie
    A landscape perspective on conservation of semi-natural grasslands.2008In: AGRICULTURE ECOSYSTEMS & ENVIRONMENT, ISSN 0167-8809, Vol. 125, no 1-4, p. 213-222Article in journal (Refereed)
    Abstract [en]

    Current agri-environmental schemes and subsidies for conservation and restoration of semi-natural grasslands do not explicitly assess land use changes affecting whole landscapes, but have so far focused on single objects and small areas. In this paper, we discuss a landscape perspective versus a "single object" perspective when conserving semi-natural grassland in agricultural landscapes. The focus is on the values biodiversity, cultural heritage, a vital countryside, and effects on economy when land use changes. We conclude that when land use change in the landscape surrounding an object, important additional effects on the different values are found. For example, a countryside where animals graze former arable fields and where marginal habitats are managed will have a positive effect, not only on the biodiversity associated to semi-natural grasslands, but also for the image of a vital and dynamic landscape. An increased number of roads, on the other hand, may negatively affect cultural heritage and decrease biodiversity in grasslands, leading to negative effects on the value of common goods through isolation. Placing objects in a larger spatial context and combining several different aspects into a landscape perspective, will improve long-term preservation of values associated to semi-natural grasslands.

  • 417.
    Lindborg, Regina
    et al.
    Stockholm University, Faculty of Science, Department of Botany.
    Cousins, Sara A. O.
    Stockholm University, Faculty of Science, Department of Botany.
    Eriksson, Ove
    Stockholm University, Faculty of Science, Department of Botany.
    Plant species response to land-use change - Campanula rotundifolia, Primula veris and Rhinanthus minor2005In: Ecography, ISSN 0906-7590, E-ISSN 1600-0587, Vol. 28, no 1, p. 29-36Article in journal (Refereed)
    Abstract [en]

    Land use change is a crucial driver behind species loss at the landscape scale. Hence, from a conservation perspective, species response to habitat degradation or improvement of habitat quality, is important to examine. By using indicator species it may be possible to monitor long-term survival of local populations associated with land use change. In this study we examined three potential indicator (response) species for species richness and composition in Scandinavian semi-natural grassland communities: Campanula rotundifolia, Primula veris and Rhinanthus minor. With field inventories and experiments we examined their response to present land use, habitat degradation and improvement of local habitat quality. At the time scale examined, C. rotundifolia was the only species responding to both habitat degradation and improvement of habitat quality. Neither R. minor nor P. veris responded positively to habitat improvements although both responded rapidly to direct negative changes in habitat quality. Even though C. rotundifolia responded quickly to habitat degradation, it did not disappear completely from the sites. Instead, the population structure changed in terms of decreased population size and flowering frequency. It also showed an ability to form remnant populations which may increase resilience of local habitats. Although P. veris and especially R. minor responded rapidly to negative environmental changes and may be useful as early indicators of land use change, it is desirable that indicators respond to both degradation and improvement of habitat quality. Thus, C. rotundifolia is a better response species for monitoring effects of land use change and conservation measures, provided that both local and regional population dynamics are monitored over a long time period.

  • 418.
    Lindborg, Regina
    et al.
    Stockholm University, Faculty of Science, Department of Botany.
    Ehrlén, Johan
    Stockholm University, Faculty of Science, Department of Botany.
    Evaluating the extinction risk of a perennial herb: demographic data versus historical records2002In: Conservation Biology, ISSN 0888-8892, E-ISSN 1523-1739, Vol. 16, no 3, p. 683-690Article in journal (Refereed)
    Abstract [en]

    Demographic information is frequently used to project the long-term extinction risk of endangered species, but the limitations of this approach have not been extensively discussed. We examined demographic data for the endangered perennial herb Primula farinosa with matrix models to assess population growth rates and extinction risks. The data came from six populations in contrasting habitats followed over a 4-year period. The results of these demographic models were compared to the results of experimental manipulations and to the actual change in occurrence of P. farinosa over a 70-year period in different habitat types. According to demographic models, all managed populations had a projected negative population growth rate and experienced a high extinction risk in 100 years, whereas unmanaged populations had increasing population sizes. In contrast, experiments and historical records suggested that continuous grazing is positively correlated with population persistence. Our results thus show that demographic studies done during a transient phase of population growth after management cessation may not capture the long-term changes. In such cases, projections of population growth rates may give misleading guidance for conservation. Short-term demographic studies are in many cases unlikely to correctly assess the survival probability of a species. We therefore argue that complementary information, such as long-term historical data or experimental manipulations of the environment, should be used whenever possible.

  • 419.
    Lindborg, Regina
    et al.
    Stockholm University, Faculty of Science, Department of Systems Ecology.
    Eriksson, O.
    Department of Botany.
    Effects of grassland restoration on plant species richness in Swedish agricultural landscapes.2008In: Biodiversity and animal feed - future challenges for grassland production, EGF Conference, Uppsala 2008., 2008Conference paper (Refereed)
  • 420.
    Lindborg, Regina
    et al.
    Stockholm University, Faculty of Science, Department of Botany.
    Eriksson, Ove
    Stockholm University, Faculty of Science, Department of Botany.
    Effects of restoration on plant species richness and composition in Scandinavian semi-natural grasslands2004In: Restoration Ecology, ISSN 1061-2971, E-ISSN 1526-100X, Vol. 12, no 3, p. 318-326Article in journal (Refereed)
    Abstract [en]

    Plant species richness in rural landscapes of northern Europe has been positively influenced by traditional management for millennia. Owing to abandonment of these practices, the number of species-rich semi-natural grasslands has decreased, and remaining habitats suffer from deterioration, fragmentation, and plant species decline. To prevent further extinctions, restoration efforts have increased during the last decades, by reintroducing grazing in former semi-natural grasslands. To assess the ecological factors that might influence the outcome of such restorations, we made a survey of semi-natural grasslands in Sweden that have been restored during the last decade. We investigated how plant species richness, species density, species composition, and abundance of 10 species that are indicators of grazing are affected by (1) the size of the restored site, (2) the time between abandonment of grazing and restoration, (3) the time elapsed since restoration, and (4) the abundance of trees and shrubs at the restored site. Only two factors, abundance of trees and shrubs and time since restoration, were positively associated with total species richness and species density per meter square at restored sites. Variation in species composition among restored sites was not related to any of the investigated factors. Species composition was relatively similar among sites, except in mesic/wet grasslands. The investigated factors had small effects on the abundance of the grazing-indicator species. Only Campanula rotundifolia responded to restoration with increasing abundance and may thus be a suitable indicator of improved habitat quality. In conclusion, positive effects on species richness may appear relatively soon after restoration, but rare, short-lived species are still absent. Therefore, remnant populations in surrounding areas may be important in fully recreating former species richness and composition.

  • 421.
    Lindborg, Regina
    et al.
    Stockholm University, Faculty of Science, Department of Botany.
    Eriksson, Ove
    Stockholm University, Faculty of Science, Department of Botany.
    Historical landscape connectivity affects present plant species diversity2004In: Ecology, ISSN 0012-9658, E-ISSN 1939-9170, Vol. 85, no 7, p. 1840-1845Article in journal (Refereed)
    Abstract [en]

    Transformation of landscapes is considered to be one of the main drivers behind species loss, regionally and globally. Theory and empirical studies suggest that landscape structure influences species diversity in many habitats. These effects may be manifested at different spatial scales depending on species response to landscape heterogeneity. A similar, but often neglected, scaling issue concerns the temporal scale of species response to landscape change. In this study, we found time lags of 50-100 years in the response of plant species diversity to changing configuration of habitats in the landscape. When analyzing remnants of traditionally managed seminatural grasslands in Sweden, we found that species diversity was not related to present-day connectivity of the investigated sites, irrespective of spatial scale (3.1-12.5 km(2)). However, when using maps depicting landscapes 50 and 100 years ago, respectively, strong positive effects of habitat connectivity appeared, at increasing spatial scale for the older landscapes. Thus, analyses of how species diversity relates to present-day landscapes may be misleading, and future species loss may be expected even if the present landscape is maint.

  • 422.
    Lindborg, Regina
    et al.
    Stockholm University, Faculty of Science, Department of Systems Ecology. Stockholm University, Stockholm Resilience Centre.
    Stenseke, Marie
    Cousins, Sara A.O.
    Stockholm University, Faculty of Science, Department of Physical Geography and Quaternary Geology.
    Bengtsson, Jan
    Berg, Åke
    Gustafsson, Tomas
    Sjödin, N. Erik
    Eriksson, Ove
    Stockholm University, Faculty of Science, Department of Botany.
    Investigating biodiversity trajectories using scenarios – Lessons from two contrasting agricultural landscapes2009In: Journal of Environmental Management, ISSN 0301-4797, E-ISSN 1095-8630, Vol. 91, p. 499-508Article in journal (Refereed)
    Abstract [en]

    Agriculture is the major land use at a global scale. In addition to food production, multifunctionality of landscapes, including values and ecosystem services like biodiversity, recreation and culture, is now focus for management. This study explores how a scenario approach, involving different stakeholders, may help to improve landscape management for biodiversity conservation. Local farmers and executives at the County Administrative Board were invited to discuss rural development and conditions for farmland biodiversity in two Swedish landscapes. The potential biodiversity for three future land use scenarios for the two landscapes was discussed: nature conservation, outdoor recreation and energy production, and compared with current and historical landscapes in each region.

    Analyses of habitat areas, connectedness and landscape diversity suggested that the energy and recreation scenarios had a negative impact on farmland biodiversity, whereas the nature conservation scenario, the current and historically reconstructed landscapes had a higher potential for biodiversity. The farmers appreciated the nature conservation scenario, but also the energy production scenario and they highlighted the need of increased subsidies for management of biodiversity. The farmers in the high production area were less interested in nature quality per se. The executives had similar opinions as the farmers, but disagreed on the advantages with energy production, as this would be in conflict with the high biodiversity and recreational values. The local physical and socio-economical conditions differ between landscapes and potentially shaped the stakeholders emotional attachment to the local environment, their opinions and decisions on how to manage the land. We stress the importance of incorporating local knowledge, visions and regional prerequisites for different land uses in conservation, since site and landscape specific planning for biodiversity together with a flexible subsidy system are necessary to reach the conservation goals within EU.

  • 423. Linder, H. Peter
    et al.
    Antonelli, Alexandre
    Humphreys, Aelys M.
    Stockholm University, Faculty of Science, Department of Botany. Imperial College London .
    Pirie, Michael D.
    Wuest, Rafael O.
    What determines biogeographical ranges?: Historical wanderings and ecological constraints in the danthonioid grasses2013In: Journal of Biogeography, ISSN 0305-0270, E-ISSN 1365-2699, Vol. 40, no 5, p. 821-834Article in journal (Refereed)
    Abstract [en]

    Aim We sought to understand the variables that limit the distribution range of a clade (here the danthonioid grasses). We tested time, area of origin, habitat suitability, disjunction width and nature, and wind direction as possible range determinants. Location Global, but predominantly the Southern Hemisphere. Methods We mapped the range of the subfamily Danthonioideae, and used 39,000 locality records and an ensemble modelling approach to define areas with suitable danthonioid habitat. We used a well-sampled, dated phylogeny to estimate the number and direction of historical dispersal events, based on parsimony optimization. We tested for the impact of wind direction on dispersal rate using a likelihood approach, and for the effects of barrier width with a regression approach. Results We found 17 geographically isolated areas with suitable habitats for danthonioids. All currently suitable Southern Hemisphere areas have been occupied, but three apparently suitable areas in the Northern Hemisphere have not. We infer that southern Africa was first occupied in the Oligocene and that dispersal to the other areas was initiated in the middle Miocene. Inferred dispersal rate was correlated with the width of the disjunctions, up to a distance of 5000km. There was no support for wind direction having influenced differences in dispersal rate. Main conclusions The current range of the Danthonioideae can be predicted ecologically (areas with suitable habitat) and historically (the width of the disjunctions separating the areas with suitable habitat and the area of origin). The direction of dispersal is dictated by the area of origin and by serendipity: there is no evidence for general patterns of dispersal, for example for dispersal occurring more frequently over land than over sea or in an easterly versus a westerly direction around the Southern Hemisphere. Thus the range and range-filling of Danthonioideae can be accounted for by surprisingly few variables: habitat suitability, distance between suitable areas, and area of origin.

  • 424.
    Lindgren, Åsa
    Stockholm University, Faculty of Science, Department of Botany.
    Effects of herbivory on arctic and alpine vegetation2007Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    The distribution of plant species and functional traits in alpine and arctic environments are determined by abiotic conditions, but also by biotic interactions. In this thesis, I investigate interactions among plants and herbivory effects on plant community composition and plant functional traits in three different regions: Swedish Lapland, Beringia (USA/Russia) and Finnmark (Norway). Reindeer grazing was found to be extensive in southern Lapland and had limited effects on plant community composition and seedling germination. However, reindeer presence was found to influence plant functional traits, particularly in the subalpine birch forest. Tall herbs were lower and had lower SLA when reindeer were present, while small herbs showed an opposite pattern. The contrasting effects on the two herb groups are probably explained by a competitive release for small herbs when the tall herbs are suppressed by reindeer. Rodents had the largest relative impact on plant community composition in southern Lapland and this is consistent with the study from Finnmark, where rodents heavily affected dwarf shrubs on predator-free islands. With no predators present, vole densities increased profoundly and almost depleted some dwarf shrub species. These results support the idea that small mammals in arctic and alpine tundra are controlled by predators (i.e. top-down). However, a decrease in the nutritional quality in a sedge after defoliation gives support for the idea that small mammals are regulated by plant quality (i.e. bottom-up). In Beringia, small and large herbivores differed in the relation to plant community composition, since large herbivores were related to species richness and small herbivores were related to plant abundance. Plant functional traits were related only to large herbivores and standing crop of vascular plants.

  • 425.
    Lindgren, Åsa
    et al.
    Stockholm University, Faculty of Science, Department of Botany.
    Ehrlén, Johan
    Bergström, Roger
    Danell, Kjell
    Ericsson, Göran
    Skarpe, Christina
    Herbivory and plant biodiversity in an arctic environmentManuscript (Other academic)
  • 426.
    Lindgren, Åsa
    et al.
    Stockholm University, Faculty of Science, Department of Botany.
    Eriksson, Ove
    Stockholm University, Faculty of Science, Department of Botany.
    Moen, Jon
    The impact of disturbance and seed availability on germination in alpine vegetation in the Scandinavian mountains2007In: Arctic, Antarctic and Alpine research, ISSN 1523-0430, E-ISSN 1938-4246, Vol. 39, no 3, p. 449-454Article in journal (Refereed)
    Abstract [en]

    The availability of seeds and microsites are limiting factors for many plant species of different vegetation types. We have investigated the existence of such limitations in two habitats, an alpine heath and a subalpine birch forest, where abiotic factors are hypothesized to be the main determining factor of plant species distributions. Both habitats are characterized by a short growing season and cold temperatures, and the alpine heath is also constrained by low productivity. A seed addition experiment including six vascular plants, selected by different functional traits and occurrence, showed that seed limitation was an important factor in these habitats. Removal of the aboveground biomass (controlled disturbance) increased germination only for some species. The effect of reindeer presence was found to be of less importance, probably due to low and varying densities of reindeer. To conclude, we found that seed limitation was the most important factor limiting the distribution of our studied species in the two alpine environments.

  • 427.
    Lindgren, Åsa
    et al.
    Stockholm University, Faculty of Science, Department of Botany.
    Klint, Johan
    Stockholm University, Faculty of Science, Department of Botany.
    Moen, Jon
    Defense mechanisms against grazing: a study of trypsin inhibitor responses to simulated grazing by the sedge Carex bigelowii2007In: Oikos, ISSN 0030-1299, E-ISSN 1600-0706, Vol. 116, no 9, p. 1540-1546Article in journal (Refereed)
    Abstract [en]

    Trypsin inhibitors have been suggested to constitute an inducible defense in the sedge Carex bigelowii, and some former studies suggest that this might be a cause for the cyclic population dynamics in many alpine and arctic small mammals, for example lemmings (Lemmus lemmus). We investigated this further by using a method of simulated grazing (clipping) at different intensities, in three different habitats with varying resource availability, with different harvest times (hours after clipping), and two different stages of ramets (reproductive/vegetative) in a study from the Swedish mountain range. Our results do not indicate that C. bigelowii has an inducible defense constituted by an increase in trypsin inhibitor activity (TIA), but rather that the amount of soluble plant proteins (SPP) is lowered in wounded plants. The responses were somewhat different in the three habitats, with ramets growing in the marsh showing the highest ratio of TIA to SPP, due to low amounts of SPP. We did not find any significant effects of harvest time, or of the stage of the ramet that could support the hypothesis of an inducible defense. To conclude, we could not find any evidence for an inducible defense consisting of trypsin inhibitors in Carex bigelowii ramets, but we did find variations in the amount of SPP that may have nutritional consequences for herbivores.

  • 428.
    Lindgren, Åsa
    et al.
    Stockholm University, Faculty of Science, Department of Botany.
    Moen, Jon
    Eriksson, Ove
    The effect of different herbivore groups on the vegetation in subalpine birch forests and alpine heathsManuscript (Other academic)
  • 429.
    Lledó, María Dolores
    et al.
    Royal Botanic Gardens, Kew, UK.
    Karis, Per Ola
    Stockholm University, Faculty of Science, Department of Botany.
    Crespo, Manuel B.
    Universidad de Alicante, Spain.
    Fay, Michael F.
    Royal Botanic Gardens, Kew, UK.
    Chase, Mark W.
    Royal Botanic Gardens, Kew, UK.
    Endemism and evolution in Macaronesian and Mediterranean Limonium taxa2011In: The biology of island floras / [ed] David Bramwell & Juli Caujapé-Castells, Cambridge University Press, 2011, p. 325-337Chapter in book (Other academic)
    Abstract [en]

    The study of plant speciation on oceanic islands has improved enormously with the help of molecular systematics. Studies have targeted groups present on both the mainland and islands with the aim of understanding plant migration and evolution in isolation. In addition, relatively young volcanic islands give the opportunity to place the evolutionary process in a time frame, by dating molecular trees according to the age of the islands or by relying on the fossil record. Molecular phylogenetics can also be valuable in helping to reconstruct character evolution and understand the syndrome of characters diagnosing oceanic species.

    Frontmatter:

    •  Read PDF

    pp. i-ivContents:

    •  Read PDF

    pp. v-viiContributors:

    •  Read PDF

    pp. viii-xiiPreface:

    •  Read PDF

    pp. xiii-xvi1 - Introduction: islands and plants:

    •  Read PDF

    By David Bramwellpp. 1-102 - The reproductive biology of island plants:

    •  Read PDF

    By Daniel J. Crawford, Gregory J. Anderson and Gabriel Bernardellopp. 11-363 - Spatial methodologies in historical biogeography of islands:

    •  Read PDF

    By Paula Posadas, Jorge V. Crisci and Liliana Katinaspp. 37-564 - Origin and evolution of Hawaiian endemics: new patterns revealed by molecular phylogenetic studies:

    •  Read PDF

    By Sterling C. Keeley and Vicki A. Funkpp. 57-885 - Origins and evolution of Galapagos endemic vascular plants:

    •  Read PDF

    By Alan Tye and Javier Francisco-Ortegapp. 89-1536 - The plants of the Caribbean islands: a review of the biogeography, diversity and conservation of a storm-battered biodiversity hotspot:

    •  Read PDF

    By Michael Maunder et al.pp. 154-1787 - The biogeography of Madagascar palms:

    •  Read PDF

    By John Dransfield and Mijoro Rakotoarinivopp. 179-1968 - Evolution and

  • 430.
    Lohtander, Katileena
    Stockholm University, Faculty of Science, Department of Botany.
    Phylogeny and species delimitation in Roccellaceae and Physciaceae (Euascomycetes)2000Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    DNA sequence data (the ITS region and Group I Introns) from the nuclear ribosomal repeat (rDNA), partial β-tubulin gene sequences, RAPD markers, and some morphological characters were analysed phylogenetically in order to examine relationships in lichenized Euascomycetes, from the species level to higher taxonomic levels. The species level studies comprise some so-called species pairs in two families, Roccellaceae (Arthoniales) and Physciaceae (Lecanorales). In order to determine whether the asexual specimens studied represent clonal species that have arisen from their fertile counterparts in a single event, or alternatively have multiple origins and are therefore conspecific, the ITS region, and in some cases the β-tubulin gene sequences and RAPD markers were obtained for several fertile and sterile specimens of various species pairs. A novel phylogenetic analysis of the species pair Phaeophyscia ciliata/P. orbicularis was introduced in this thesis. Molecular methods were also used to resolve the phylogeny of the family Physciaceae and the genus Physcia within it. The utility of indels (gaps) and different gap-coding in molecular data was also discussed.

    The DNA sequence data appeared to be informative. The ITS sequences provided abundant phylogenetic information at the family level, as well as at the genus and, in some cases, species levels. The intron positions varied between different genera and insertions were found to provide phylogenetic information mostly within and between species. The b-tubulin gene appeared to be an especially informative genetic marker at the species level.

    The results from the species pair studies indicated that the sexual and asexual specimens might be conspecific in many cases, since sexual and asexual counterparts were intermixed in the phylogenetic trees.

  • 431. Lorence, David H.
    et al.
    Wagner, Warren L.
    Mouly, Arnaud
    Stockholm University, Faculty of Science, Bergianska botaniska trädgården (tills m Kungl. Vet. Ak.). Department of Botany. Plant Systematics.
    Florence, Jacques
    Revision of Ixora (Rubiaceae) in the Marquesas Islands (French Polynesia)2007In: Botanical Journal of the Linnean Society, Vol. 155, p. 581-597Article in journal (Refereed)
  • 432. Luis Godinez-Ortega, Jose
    et al.
    Snoeijs, Pauli
    Robledo, Daniel
    Freile-Pelegrin, Yolanda
    Pedersen, Marianne
    Stockholm University, Faculty of Science, Department of Botany.
    Growth and pigment composition in the red alga Halymenia floresii cultured under different light qualities2008In: Journal of Applied Phycology, ISSN 0921-8971, E-ISSN 1573-5176, Vol. 20, no 3, p. 253-260Article in journal (Refereed)
    Abstract [en]

    Halymenia floresii is an edible species consumed in some Asian markets. In the Yucatan peninsula coast of Mexico, H. floresii dominates rocky substrata between 3 and 40 m where it grows up to 50 cm high. After analyzing the seasonal pattern of pigment content on H. floresii, we evaluate if and how the spectral composition of light affects growth and pigment dynamics under laboratory cultivation. Unialgal cultures were exposed to white, blue, red and green light in a 3-week experiment. Green light resulted in the highest algal growth rates. Synthesis of chlorophyll a, alpha-carotene and lutein, but not of beta-carotene, was induced by white or green light. Phycocyanin synthesis was stimulated by blue light and phycoerythrin synthesis by blue or red light. Light quality treatments may be used to manipulate pigment composition in Halymenia floresii cultures.

  • 433.
    Lundberg, Magnus
    Stockholm University, Faculty of Science, Department of Botany.
    Systematics and polyploid evolution in Potentilleae (Rosaceae)2011Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    This thesis comprises studies of the phylogenetic relationships in the flowering plant clade Potentilleae in Rosaceae. The relationships were elucidated by using DNA sequence data from the nuclear genome as well as from the plastid genome. In particular, the focus of the studies was the investigation of allopolyploidy, i.e. speciation as a result of hybridization and subsequent chromosome doubling. A phylogenetic method was used for identifying allopolyploidy through comparison of trees resulting from the analyses of different DNA sequences. Five sub-clades were investigated. First, both the sister clades that together contain all of Potentilleae: Fragariinae and Potentilla. Secondly, three subclades of Fragariinae, namely Alchemilla in wide sense, Sibbaldia and relatives, and Fragaria. The aim was to unravel the phylogenetic relationships, including instances of allopolyploidy. Classification issues were discussed in relation to the phylogenetic results. The split between Potentilla (=Potentillinae) and Fragariinae received better support than in previous studies. The phylogeny of Fragariinae was found to be consistent with classifying ten genera: Alchemilla in wide sense (incl. Aphanes and Lachemilla), Comarum, Sibbaldia, Sibbaldianthe, Sibbaldiopsis, Chamaerhodos, Drymocallis, Dasiphora, Potaninia, Fragaria, and also including a few orphan Potentilla species. The segregated genera Ivesia, Horkelia, Horkeliella and Duchesnea were found to be nested within Potentilla, corroborating earlier studies, while the segregated genus Argentina (P. anserina and close relatives) showed an ambiguous position. Plastid and nuclear (ribosomal) phylogenies were compared and incongruences were detected as potential instances of allopolyploid speciation. Five strongly supported incongruences were detected in Fragariinae and four of them were considered to be potentially caused by allopolyploidy. In addition, five supported incongruences were found in Potentilla. Alchemilla in the wide sense was found to contain four major clades, African Alchemilla, Eurasian Alchemilla, Lachemilla and Aphanes. Both Lachemilla and Aphanes were nested within Alchemilla and it was suggested that the name Alchemilla should be used in the wide sense, i.e. including both the genera Lachemilla and Aphanes. The genus Sibbaldia as commonly classified was shown to be polyphyletic in five different places in Potentilleae. Three Sibbaldia clades ended up in Fragariinae and two in Potentilla. A phylogeny of Fragaria, based on a nuclear low/single copy DNA region was estimated. The gene copy phylogeny was used to construct a reticulate tree hypothesizing allopolyploid speciation events. The evolution of Fragaria was shown to have been shaped by polyploidy.

  • 434.
    Lundberg, Magnus
    et al.
    Stockholm University, Faculty of Science, Department of Botany.
    Eriksson, Torsten
    Zhang, Qian
    Davis, Tom
    New insights into polyploid evolution in Fragaria (Rosaceae) based on the single/low copy nuclear intergenic region RGA1-SubtilaseManuscript (preprint) (Other academic)
    Abstract [en]

    A phylogenetic study of the genus Fragaria (Rosaceae) was performed based on the nuclear low/singlecopy intergenic region between the two genes Resistance Gene Analogue 1 (RGA1) and Subtilase(Subt). Potential diploid progenitors of the polyploid Fragaria species were detected and autopolyploid species were distinguished from allopolyploid. Our analyses indicate nine separate events of polyploidization in the evolution of Fragaria, of which three are of autopolyploid and six are of allopolyploid origin. Three tetraploid Fragaria have a probable autopolyploid origin, while a fourth one is most likely an allopolyploid. Fragaria nipponica is the diploid progenitor of autotetraploid F. tibetica, a diploid of the F. nipponica lineage is the progenitor of autotetraploid F. gracilis and F. vesca or more likely F. mandshurica is the diploid progenitor of autotetraploid F. orientalis. The progenitorsof the allotetraploid F. corymbosa are a diploid of the F. nipponica lineage and a diploid sister to the F.nipponica lineage. The hexaploid F. moschata originated after two events of allopolyploidization. First,a hybridization event involving the two diploids F. vesca and F. viridis took place, resulting in an undescribed allotetraploid and secondly, this allotetraploid hybridized with a diploid of the F. iinumae lineage. The octoploid lineage that gave rise to the two species F. virginiana and F. chiloensis was formed after an allopolyploidization event between F. moschata and a diploid of the F. iinumae lineage.The decaploid F. iturupensis originated after an allopolyploidization event between the octoploid lineage and a diploid of the F. iinumae lineage. The potential new species, formerly known as F.virginiana ssp. platypetala, originated after an allopolyploidization event between F. virginiana and a diploid Fragaria basally placed in our phylogeny, close to F. daltoniana.

  • 435.
    Lundberg, Magnus
    et al.
    Stockholm University, Faculty of Science, Department of Botany.
    Töpel, Mats
    Gothenburg University, Department of Environmental Sciences.
    Eriksen, Bente
    Gothenburg University, Department of Environmental Sciences.
    Nylander, Johan
    Stockholm University, Faculty of Science, Department of Botany.
    Eriksson, Torsten
    Stockholm University, Faculty of Science, Department of Botany. Stockholm University, Faculty of Science, The Bergius Botanical Garden Museum.
    Allopolyploidy in Fragariinae (Rosaceae): Comparing four DNA sequence regions, with comments on classification2009In: Molecular Phylogenetics and Evolution, ISSN 1055-7903, E-ISSN 1095-9513, Vol. 51, no 2, p. 269-280Article in journal (Refereed)
    Abstract [en]

    Potential events of allopolyploidy may be indicated by incongruences between separate phylogenies based on plastid and nuclear gene sequences. We sequenced two plastid regions and two nuclear ribosomal regions for 34 ingroup taxa in Fragariinae (Rosaceae), and six outgroup taxa. We found five well supported incongruences that might indicate allopolyploidy events. The incongruences involved Aphanes arvensis, Potentilla miyabei, Potentilla cuneata, Fragaria vesca/moschata, and the Drymocallis clade. We evaluated the strength of conflict and conclude that allopolyploidy may be hypothesised in the four first cases. Phylogenies were estimated using Bayesian inference and analyses were evaluated using convergence diagnostics. Taxonomic implications are discussed for genera such as Alchemilla, Sibbaldianthe, Chamaerhodos, Drymocallis and Fragaria, and for the monospecific Sibbaldiopsis and Potaninia that are nested inside other genera. Two orphan Potentilla species, P. miyabei and P. cuneata are placed in Fragariinae. However, due to unresolved topological incongruences they are not reclassified in any genus.

  • 436. Lundgren, Pernilla
    et al.
    Bauer, Karolina
    Stockholm University, Faculty of Science, Department of Botany.
    Lugomela, Charles
    Söderbäck, Erik
    Bergman, Birgitta
    Re-evaluation of the nitorgen fixation behaviour in the marine non-heterocystous cyanobacterium Lyngbya majuscula2003In: Journal of Phycology, ISSN 1529-8817, Vol. 39, no 2, p. 310-314Article in journal (Refereed)
  • 437.
    Lundgren, Pernilla
    et al.
    Stockholm University, Faculty of Science, Department of Botany. Växtfysiologi.
    Bauer, Karolina
    Stockholm University, Faculty of Science, Department of Botany. Växtfysiologi.
    Lugomela, Charles
    Söderbäck, Erik
    Stockholm University, Faculty of Science, Department of Botany. Växtfysiologi.
    Bergman, Birgitta
    Stockholm University, Faculty of Science, Department of Botany. Växtfysiologi.
    Reevaluation of the nitrogen fixation behavior in the marine non-heterocystous cyanobacterium Lyngbya majuscula2003In: Journal of Phycology, Vol. 39, no 2, p. 310-314Article in journal (Refereed)
    Abstract [en]

    Abstract: Lyngbya majuscula Harvey ex Gomont is a common marine cyanobacterium in tropical and subtropical near-shore waters. A few reports have indicated that L. majuscula fixes nitrogen only in the light. Because this feature is uncommon among non-heterocystous cyanobacteria, we attempted a reevaluation. Nitrogenase activity, regulation, and localization were examined over diel cycles on natural populations of L. majuscula growing in subtidal zones off Zanzibar in the western Indian Ocean. The data show that L. majuscula fixed nitrogen and synthesized nitrogenase in all cells during the dark phase of a diel cycle. During the light phase, nitrogenase was degraded to undetectable levels.

  • 438.
    Lyimo, Thomas J.
    et al.
    Department of Molecular Biology and Biotechnology, University of Dar es Salaam.
    de la Torre-Castro, Maricela
    Stockholm University, Faculty of Science, Department of Systems Ecology.
    Shaghude, Yohanna W.
    Institute of Marine Sciences, University of Dar es Salaam.
    Jiddawi S., Narriman
    Institute of Marine Sciences, University of Dar es Salaam.
    Björk, Mats
    Stockholm University, Faculty of Science, Department of Botany.
    Lindström, Lars
    Stockholm University, Faculty of Social Sciences, Department of Political Science.
    Synthesis: Towards an integrative research approach on coastal ecosystems – The example of Chwaka Bay2012In: People, Nature and Research in Chwaka Bay, Zanzibar, Tanzania / [ed] de la Torre-Castro Maricela and Lyimo Thomas J., Zanzibar Town: Western Indian Ocean Marine Science Association , 2012, p. 17-22Chapter in book (Other academic)
  • 439.
    Löfgren, Anders
    Stockholm University, Faculty of Science, Department of Botany.
    Colonisation and extinction of vascular plants on islands off the Swedish east coast2001Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Persistence of species is a function of colonisation and extinction among patches at a regional scale. A decrease in area and an increased isolation of suitable patches may result in a decreased colonisation rate and an increased extinction rate among species. A large number of species connected to semi-natural grasslands are today on the verge of extinction, due to ceased management of our semi-natural grasslands. This thesis describes patterns in colonisation, extinction and persistence among vascular plants during a century in the Blidö archipelago that have largely been transformed into forests due to the ceased management. I also examine whether species-specific traits may explain colonisation and extinction patterns both generally and more closely for Achillea millefolium and Silene viscosa.

    Extinction rate in the Blidö archipelago decreased with distance from mainland, which coincide with decreasing management intensity on the islands. Surprisingly we found that population size did not affect persistence among semi-natural grassland species. Locally abundant species were relatively more subjected to extinction than less abundant species, suggesting that former competitive species were more sensitive to the ongoing closing of the landscape. Effects of specific life-history traits on the processes of extinction and colonisation were examined, but could not in general explain why certain species connected to semi-natural grasslands had decreased or disappeared. Result from an analysis of physiological tolerance suggested that the observed closing of the open habitats have disfavoured species with a high light requirement.

    Empirical studies have shown that increased habitat fragmentation may affect plant-pollinator interactions with a reduced seed set as a result. I examined how fecundity were affected by isolation in the self-incompatibel A. millefolium, pollinated by a varity of pollinators, by doing a transplantation experiment to non-isolated and isolated islands in the Stockholm archipelago. No effects were found on pollen disposition and fecundity suggesting that species having a generalist fauna of pollinators are to a lesser extent affected by isolation than those dependent on a single pollinator or a more specialised guild of pollinators.

    Populations of S. viscosa were very persistent during a 40-year period and old records indicate a long-term persistence for some populations. Population size changes on islands were independent of each other even though closely situated. All this suggested that the distribution pattern approximates an Island-Mainland model, where a number of large populations are persistent and a number of smaller populations are more prone to extinctions due to catastrophes and environmental stochasticity. The patch occupancy was positively affected by isolation. This effect had disappeared 40 years later, which coincided with the appearance of the greylag goose (Anser anser), here shown to disperse seeds by occasionally eating seed capsules. This highlights the effect of dispersal on patch occupancy patterns.

  • 440.
    Löfstrand, Karin
    et al.
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK), Environmental Chemistry.
    Haglund, Peter
    Umeå universitet, Kemiska institutionen.
    Bergman, Åke
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK), Environmental Chemistry.
    Kautsky, Lena
    Stockholm University, Faculty of Science, Department of Botany.
    Asplund, Lillemor
    Stockholm University, Faculty of Science, Department of Materials and Environmental Chemistry (MMK), Environmental Chemistry.
    Hydroxylated and methoxylated polybrominated diphenyl ethers and polybrominated dibenzo-p-dioxins in algae and blue mussels from the Swedish coast line - patterns and correlationsManuscript (preprint) (Other academic)
  • 441.
    Lönnberg, Karin
    Stockholm University, Faculty of Science, Department of Botany.
    Effects of seed size and habitat on recruitment patterns in grassland and forest plants2012Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    A trade-off between seed size and seed number is central in seed ecology, and has been suggested to be related to a trade-off between competition and colonization, as well as to a trade-off between stress tolerance and fecundity. Large seeds endure hazards during establishment, such as shading, drought, litter coverage and competition from other plants, better than do small seeds, due to a larger amount of stored resources in the seed. Small seeds, however, are numerous and small-seeded species are therefore more fecund. Moreover, a pattern with small-seeded species being associated with open habitats and large-seeded species being associated with closed habitats has been reported in the literature. In this thesis I assess effects of seed size on recruitment, and how relationships between seed size and recruitment may relate to habitat conditions. Seed sowing experiments were performed in the field to assess inter- and intra-specific relationships between seed size and recruitment in open and closed habitats (Paper I and II). Seed removal experiments were performed in the field to assess what effects seed predation may have on a relationship between seed size and recruitment (Paper III). A garden experiment was performed based on contests between larger-seeded and smaller-seeded species, in order to examine different models on co-existence of multiple seed size strategies. The results showed that there was a weak positive relationship between seed size and recruitment in the field, and that this relationship was only weakly and inconclusively related to habitat (Paper I and II). Seed removal was negatively related to seed size in closed habitats and unrelated to seed size in open habitats (Paper III). This indicates that any positive relationship between seed size and recruitment may be an effect of higher seed removal in small-seeded species. However, when grown under controlled conditions in a garden experiment, there was a clear advantage of larger-seeded species over smaller-seeded species (Paper IV). This advantage was unaffected by seed density, indicating that there was no competitive advantage of the larger-seeded species. Instead, indirect evidence suggests that larger-seeded species exhibit higher tolerance to stress.

  • 442.
    Lönnberg, Karin
    Stockholm University, Faculty of Science, Department of Botany.
    Seed removal in relation to seed size in two contrasting habitatsManuscript (preprint) (Other academic)
  • 443.
    Lönnberg, Karin
    et al.
    Stockholm University, Faculty of Science, Department of Botany.
    Eriksson, Ove
    Stockholm University, Faculty of Science, Department of Botany.
    Relationships between intra-specific variation in seed size and recruitment in four species in two contrasting habitats2013In: Plant Biology, ISSN 1435-8603, E-ISSN 1438-8677, Vol. 15, no 3, p. 601-606Article in journal (Refereed)
    Abstract [en]

    Large seeds contain more stored resources, and seedlings germinating from large seeds generally cope better with environmental stresses such as shading, competition and thick litter layers, than seedlings germinating from small seeds. A pattern with small-seeded species being associated with open habitats and large-seeded species being associated with closed (shaded) habitats has been suggested and supported by comparative studies. However, few studies have assessed the intra-specific relationship between seed size and recruitment, comparing plant communities differing in canopy cover. Here, seeds from four plant species commonly occurring in ecotones between open and closed habitats (Convallaria majalis, Frangula alnus, Prunus padus and Prunus spinosa) were weighed and sown individually (3200 seeds per species) in open and closed-canopy sites, and seedling emergence and survival recorded over 3 years. Our results show a generally positive, albeit weak, relationship between seed size and recruitment. In only one of the species, C. majalis, was there an association between closed canopy habitat and a positive seed size effect on recruitment. We conclude that there is a weak selection gradient favouring larger seeds, but that this selection gradient is not clearly related to habitat.

  • 444.
    Lönnberg, Karin
    et al.
    Stockholm University, Faculty of Science, Department of Botany.
    Eriksson, Ove
    Stockholm University, Faculty of Science, Department of Botany.
    Rules of the seed size game: contests between large-seeded and small-seeded species2013In: Oikos, ISSN 0030-1299, E-ISSN 1600-0706, Vol. 122, no 7, p. 1080-1084Article in journal (Refereed)
    Abstract [en]

    The coexistence of multiple seed size strategies within plant communities have been considered puzzling, based on a theoretical expectation of the existence of an optimal seed size under each set of specific environmental conditions. A model aimed at explaining the coexistence of different seed sizes has been suggested, where a seed size – seed number trade-off is connected to a trade-off between competition and colonization, leading to a competitive advantage in larger-seeded species and a colonization advantage in smaller-seeded species. Recently an alternative model has been suggested, based on a trade-off between stress tolerance and fecundity, associated with the variation from large to small seeds. Here, we examine the role of seed size for recruitment in two-species contests subjected to various treatments. In a garden experiment seeds of 14 plant species were combined pair-wise into seven pairs, each with one larger-seeded species and one smaller-seeded species. Each species-pair was sown with sparse and dense seed densities and subjected to different treatments of shading and litter. Recruitment was recorded during two years. Our results showed a general advantage of larger-seeded species over smaller-seeded species. This seed size advantage increased in treatments with litter, whereas there were minor effects of shade, and no effect of seed density was found. We thus found little support for a density dependent seed size game as assumed in models of a competition-colonization trade-off, whereas our results fit well with a model based on a trade-off between stress tolerance and fecundity. Our experiment provides novel empirical data to theoretical models on co-existence between multiple seed size strategies.

  • 445.
    Lönnberg, Karin
    et al.
    Stockholm University, Faculty of Science, Department of Botany.
    Eriksson, Ove
    Stockholm University, Faculty of Science, Department of Botany.
    Seed size and recruitment patterns in a gradient from grassland to forest2012In: Ecoscience, ISSN 1195-6860, Vol. 19, no 2, p. 140-147Article in journal (Refereed)
    Abstract [en]

    Seedlings germinating from large seeds are known to endure hazards such as shading, competition, and litter coverage better than seedlings germinating from small seeds. However, few studies have assessed the relationships between seed size and recruitment comparing plant communities with different structures in order to establish the conditions under which a seed-size advantage prevails. Here, seeds from 20 species varying in seed size from 0.05 to 17.8 mg were sown in 6 different vegetation types, representing a gradient from open grassland to closed canopy coniferous forest. We hypothesized that the effect of seed size on recruitment is generally positive, but that there is a stronger positive effect of seed size in closed than in open communities. Our results provided only limited support for this hypothesis. Firstly, the results varied between years, suggesting that any seed size advantage may depend on factors varying on an annual basis. Secondly, although there were trends of significantly positive relationships between seed size and seedling emergence, seedling survival, and recruitment success, particularly in relatively more closed vegetation types, the strongest positive effects of seed size were found in intermediate (semi-open) habitats along the gradient. We conclude that the filtering of species into the investigated communities is only weakly related to seed size, and that several factors other than canopy probably influence the link between seed size and recruitment.

  • 446.
    Lönnell, Niklas
    et al.
    Stockholm University, Faculty of Science, Department of Botany.
    Hylander, Kristoffer
    Stockholm University, Faculty of Science, Department of Botany.
    Jonsson, Bengt Gunnar
    Sundberg, Sebastian
    The fate of the missing spores patterns of realized dispersal beyond the closest vicinity of a sporulating moss2012In: PLoS ONE, ISSN 1932-6203, E-ISSN 1932-6203, Vol. 7, no 7, p. e41987-Article in journal (Refereed)
    Abstract [en]

    It is well-known that many species with small diaspores can disperse far during extended temporal scales (many years). However, studies on short temporal scales usually only cover short distances (in, e.g., bryophytes up to 15 m). By using a novel experimental design, studying the realized dispersal, we extend this range by almost two orders of magnitude. We recorded establishment of the fast-growing moss Discelium nudum on introduced suitable substrates, placed around a translocated, sporulating mother colony. Around 2,000 pots with acidic clay were placed at different distances between 5 m and 600 m, in four directions, on a raised bog, with increased pot numbers with distance. The experiment was set up in April-May and the realized dispersal (number of colonized pots) was recorded in September. Close to the mother colony (up to 10 m), the mean colonization rates (ratio of colonized pots) exceeded 50%. At distances between 10 and 50 m colonization dropped sharply, but beyond 50 m the mean colonization rates stabilized and hardly changed (1-3%). The estimated density of spores causing establishments at the further distances (2-6 spores/m(2)) was realistic when compared to the estimated spore output from the central colonies. Our study supports calculations from earlier studies, limited to short distances, that a majority of the spores disperse beyond the nearest vicinity of a source. The even colonization pattern at further distances raises interesting questions about under what conditions spores are transported and deposited. However, it is clear that regular establishment is likely at the km-scale for this and many other species with similar spore output and dispersal mechanism.

  • 447.
    Malmvärn, Anna
    et al.
    Stockholm University, Faculty of Science, Department of Environmental Chemistry.
    Zebühr, Yngve
    Stockholm University, Faculty of Science, Department of Applied Environmental Science (ITM).
    Kautsky, Lena
    Stockholm University, Faculty of Science, Department of Botany.
    Bergman, Åke
    Stockholm University, Faculty of Science, Department of Environmental Chemistry.
    Asplund, Lillemor
    Stockholm University, Faculty of Science, Department of Applied Environmental Science (ITM).
    Hydroxylated and methoxylated polybrominated diphenyl ethers and polybrominated dibenzo-p-dioxins in red alga and cyanobacteria living in the Baltic Sea2008In: Chemosphere, ISSN 0045-6535, E-ISSN 1879-1298, Vol. 72, no 6, p. 910-916Article in journal (Refereed)
    Abstract [en]

    Hydroxylated polybrominated diphenyl ethers (OH-PBDEs) and methoxylated polybrominated diphenyl ethers (MeO-PBDEs) are present in the ecosystem of the Baltic Sea. OH-PBDEs are known to be both natural products from marine environments and metabolites of the anthropogenic polybrominated diphenyl ethers (PBDEs), whereas, MeO-PBDEs appear to be solely natural in origin. Polybrominated dibenzo-p-dioxins (PBDDs) are by-products formed in connection with the combustion of brominated flame retardants (BFRs), but are also indicated as natural products in a red alga (Ceramium tenuicorne) and blue mussels living in the Baltic Sea. The aims of the present investigation were to quantify the OH-PBDEs and MeO-PBDEs present in C. tenuicorne; to verify the identities of PBDDs detected previously in this species of red alga and to investigate whether cyanobacteria living in this same region of the Baltic Sea contain OH-PBDEs, MeO-PBDEs and/or PBDDs. The red alga was confirmed to contain tribromodibenzo-p-dioxins (triBDDs), by accurate mass determination and additional PBDD congeners were also detected in this sample. This is the first time that PBDDs have been identified in a red alga. The SigmaOH-PBDEs and SigmaMeO-PBDEs concentrations, present in C. tenuicorne were 150 and 4.6ngg(-1) dry weight, respectively. In the cyanobacteria 6 OH-PBDEs, 6 MeO-PBDEs and 4 PBDDs were detected by mass spectrometry (electron capture negative ionization (ECNI)). The PBDDs and OH-PBDEs and MeO-PBDEs detected in the red alga and cyanobacteria are most likely of natural origin.

  • 448.
    Mamboya, F.A
    et al.
    Stockholm University, Faculty of Science, Department of Botany.
    Lyimo, T.J.
    University of Dar es Salaam.
    Landberg, Tommy
    Stockholm University, Faculty of Science, Department of Botany.
    Björk, Mats
    Stockholm University, Faculty of Science, Department of Botany.
    Influence of combined changes in salinity and copper modulation on growth and copper uptake in the tropical green macroalga Ulva reticulata.2009In: Estuarine, Coastal and Shelf Science, ISSN 0272-7714, E-ISSN 1096-0015, Vol. 84, no 3, p. 326-330Article in journal (Refereed)
    Abstract [en]

    The influence of salinity on growth and Cu uptake in the green macroalga Ulva reticulata collected from the intertidal area in the Western Indian Ocean was studied under controlled laboratory conditions. Exposure concentrations ranged from 5 to 500 μg Cu l−1 at five salinities (ranging 20–40). The accumulation of Cu increased with decreasing salinity, so that the uptake at 500 μg Cu l−1 was approximately 2.7, 2.4 and 2.0 times higher at salinities of 20, 25, and 30 respectively, than uptake at salinity of 35, and with uptake being lowest at salinity of 40. Ulva maintained a positive growth rate over the whole salinity range (20–40), with highest rates at salinity of 35. When exposing to Cu at low salinities (20 and 25), the growth rate of Ulva was strongly inhibited suggesting an increase in toxicity of Cu with decreasing salinity. EC50 and NOEC increased with increase in salinity, implying a reduced Cu toxicity at high salinities. It was concluded that salinity needs to be considered when using macroalgae, such as U. reticulata, as a bioindicator of heavy metals in areas with heavy rainfall, underground fresh water intrusion or in estuaries, as they might accumulate more metals and be more negatively affected.

  • 449.
    Mamboya, Florence Alex
    Stockholm University, Faculty of Science, Department of Botany.
    Heavy metal contamination and toxicity: Studies of Macroalgae from the Tanzanian Coast2007Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Concentrations of various metals are elevated above background levels in several intertidal areas along the Tanzanian coasts. However, there is little available information concerning the toxicity of these metals and how the uptake of these metals by bioindicators are influenced by external factors, such as heavy rains and increased coastal eutrophication, which tend to fluctuate.

    The present study focused on the uptake and toxicity of Cu and Zn in two common macroalgal species, Padina gymnospora (Phaeophyta) and Ulva reticulata (Chlorophyta). Laboratory studies were performed where metal content, growth (DGR), maximal quantum yields (Fv/Fm) and protein expression patterns (in Ulva) were measured as a response to exposure to Cu and Zn. The levels of metals accumulated in algal tissues correlated well to exposure concentrations and the longer the exposure time, the greater the uptake. However, an increased nutrient load (tested on Padina) or dilution of the seawater (tested on Ulva) affected both uptake of metals and their toxic effects. Here, DGR was more affected than Fv/Fm, suggesting DGR to be the more sensitive indicator of Cu and Zn toxicity. As shown by 2-D gel electrophoresis, more than ten proteins were up-regulated in U. reticulata after being exposed to Cu (1μg/L), while at higher concentrations (10 and 100 μg/L) of Cu numerous proteins were down-regulated.

    P. gymnospora was also used as a bioindicator to monitor long-term (1994–2005) and seasonal in-year variations in heavy metal concentrations in the Zanzibar Channel. No clear overall trends were revealed, but analysis of the combined dataset clearly pinpointed the most contaminated sites. It was concluded that seasonal and long-term variations, as well as environmental conditions need to be taken into consideration when using macroalgae as bioindicators.

  • 450.
    Mamboya, Florence
    et al.
    Stockholm University, Faculty of Science, Department of Botany.
    Lyimo, Thomas
    Björk, Mats
    Copper affects protein expression pattern and maximum quantum yield in the green macroalga Ulva reticulataManuscript (Other academic)
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