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  • 151.
    Diez, Beatriz
    et al.
    Stockholm University, Faculty of Science, Department of Botany.
    Bergman, Birgitta
    Stockholm University, Faculty of Science, Department of Botany.
    Pedros-Alio, Carlos
    Anto, Meritxell
    Snoeijs, Pauline
    Stockholm University, Faculty of Science, Department of Systems Ecology.
    High cyanobacterial nifh gene diversity in arctic seawater and sea ice brine2012In: Environmental Microbiology Reports, ISSN 1758-2229, E-ISSN 1758-2229, Vol. 4, no 3, p. 360-366Article in journal (Refereed)
    Abstract [en]

    Although cyanobacterial diazotrophs are common in Arctic terrestrial and freshwater habitats, they have been assumed to be absent from Arctic marine habitats. We report here a high diversity of cyanobacterial nifH genes in Fram Strait and the Greenland Sea. The nifH gene encodes the iron protein of the nitrogenase enzyme complex, which is essential for biological N2 fixation. Using primers specific for nifH genes we uncovered communities of autotrophic and heterotrophic bacteria in sea ice brine and seawater between latitudes 65 and 81 degrees N. Cyanobacteria (Oscillatoriales and Chroococcales) with known marine planktonic and benthic distributions were distinguished, alongside a mix of metabolically versatile eubacteria (nifH Clusters I and III). Using primers selective for cyanobacterial nifH genes we identified filamentous non-heterocystous Trichodesmium-like and LPP (Leptolyngbya, Phormidium and Plectonema)-like Oscillatoriales, as well as Cyanothece-like Chroococcales in a brine sample from 81 degrees N. The occurrence of Trichodesmium-like cyanobacteria was further confirmed by sequences of the hetR gene of Trichodesmium. Microscopic examinations confirmed the presence of viable filamentous and unicellular cyanobacteria. Our results reveal the potential for microbial N2 fixation in the Arctic seas. However, it is still left to determine if these genes are also metabolically active before any biogeochemical importance of diazotrophy in the polar oceans can be assessed.

  • 152. Dominguez-Escobar, Julia
    et al.
    Beltran, Yislem
    Bergman, Birgitta
    Stockholm University, Faculty of Science, Department of Botany.
    Diez, Beatriz
    Stockholm University, Faculty of Science, Department of Botany.
    Ininbergs, Karolina
    Stockholm University, Faculty of Science, Department of Botany.
    Souza, Valeria
    Falcon, Luisa I.
    Phylogenetic and molecular clock inferences of cyanobacterial strains within Rivulariaceae from distant environments2011In: FEMS Microbiology Letters, ISSN 0378-1097, E-ISSN 1574-6968, Vol. 316, no 2, p. 90-99Article in journal (Refereed)
    Abstract [en]

    Heterocyst-forming cyanobacteria are important players at both evolutionary and ecological scales, but to date it has been difficult to establish their phylogenetic affiliations. We present data from a phylogenetic and molecular clock analysis of heterocystous cyanobacteria within the family Rivulariaceae, including the genera Calothrix, Rivularia, Gloeotrichia and Tolypothrix. The strains were isolated from distant geographic regions including fresh and brackish water bodies, microbial mats from beach rock, microbialites, pebble beaches, plus PCC strains 7103 and 7504. Phylogenetic inferences (distance, likelihood and Bayesian) suggested the monophyly of genera Calothrix and Rivularia. Molecular clock estimates indicate that Calothrix and Rivularia originated similar to 1500 million years ago (MYA) ago and species date back to 400-300 MYA while Tolypothrix and Gloeotrichia are younger genera (600-400 MYA).

  • 153.
    D'Onofrio, Cladio
    et al.
    University of Pisa, Italy.
    Lindberg, Sylvia
    Stockholm University, Faculty of Science, Department of Botany.
    Sodium induces simultaneous changes in cytosolic calcium and pH in salt-tolerant quince protoplasts2009In: Journal of plant physiology (Print), ISSN 0176-1617, E-ISSN 1618-1328, Vol. 166, p. 1755-1763Article in journal (Refereed)
    Abstract [en]

    Previousexperimentswithsalt-resistantquinceBA29(Cydonia oblonga cv.Mill.) have shownthatthiscultivartakesupsodiumtransientlyintothecytosolofshoot protoplasts onlyintheabsenceofcalciumchloride,orat o1mMcalciumchloride. Addition ofNaClZ100mMtosingleprotoplastsfrom in vitro-cultivated quinceinthe presence of1.0mMcalciuminducedinstantchangesinthecytosolicconcentrations of calciumandprotons.Thesechangeswereinvestigatedbyuseoftetra [acetoxymethyl] estersofthefluorescentstilbenechromophoresFura2andbis- carboxyethyl-carboxyfluorescein (BCECF),respectively.ThecytosolicCa2+ dynamics in theprotoplastsweredependentontheconcentrationofNaCladded.Thechanges in calciumdifferedinamplitudeandfinalconcentrationandwerecorrelatedintime mainly withchangesinpH.Additionof100–400mMNaCltotheprotoplastscausedan oscillating increaseinthecytosoliclevelofcalcium,andthenadecrease.Addition of mannitol,ofequiosmolarconcentrationtoNaCl,didnotincreasethecytosolic calcium concentration.Moreover,therewasnoincreaseincytosoliccalciumwhen NaCl wasaddedinthepresenceofcalciumbindingethyleneglycol-bis(beta- aminoethylether)-N,N,N0,N0-tetra aceticacid(EGTA),orlantanorverapamil,two inhibitors ofplasmamembranecalciumchannels.Therefore,weconcludethat,in salt-resistant quince,sodiuminducesaninfluxofcalciumintothecytosolbyplasma membrane calciumchannels,andasimultaneousincreaseincytosolicpH.Because these changeswereobtainedinthepresenceof1mMcalciuminthemedium,they were notduetosodiumuptakeintothecytosol.

  • 154. Dostal, Petr
    et al.
    Havlickova, V
    Jorritsma-Wienk, L
    Eriksson, Ove
    Stockholm University, Faculty of Science, Department of Botany.
    Herben, T
    Interspecific competition changes reproductive output but does not increase reproductive costs in a grassland perennial.2009In: Basic and Applied Ecology, ISSN 1439-1791, E-ISSN 1618-0089, Vol. 10, p. 525-534-Article in journal (Refereed)
  • 155. Dynesius, M.
    et al.
    Hylander, K.
    Stockholm University, Faculty of Science, Department of Botany.
    Resilience of bryophyte communities to clear-cutting of boreal stream-site forests2007In: Biological Conservation, Vol. 135, p. 423-434Article in journal (Refereed)
  • 156.
    Dynesius, Mats
    et al.
    Umeå University.
    Hylander, Kristoffer
    Stockholm University, Faculty of Science, Department of Botany.
    Nilsson, Christer
    Umeå University.
    High resilience in stream-side bryophyte assemblages in boreal forests2009In: Ecology, ISSN 0012-9658, E-ISSN 1939-9170, Vol. 90, p. 1042-1054Article in journal (Refereed)
  • 157. Díez, Beatriz
    et al.
    Bauer, Karolina
    Stockholm University, Faculty of Science, Department of Botany.
    Bergman, Birgitta
    Epilithic cyanobacterial communities of a marine tropical beach rock (Heron Island, Great Barrier Reef); diversity and diazotrophyManuscript (Other academic)
  • 158.
    Díez, Beatriz
    et al.
    Stockholm University, Faculty of Science, Department of Botany.
    Bauer, Karolina
    Stockholm University, Faculty of Science, Department of Botany.
    Bergman, Birgitta
    Stockholm University, Faculty of Science, Department of Botany.
    Epilithic cyanobacterial communities of a marine tropical beach rock (Heron Island, Great Barrier Reef): diversity and diazotrophy.2007In: Appl Environ Microbiol, ISSN 0099-2240, Vol. 73, no 11, p. 3656-68Article in journal (Refereed)
  • 159.
    Ehrlén, Johan
    et al.
    Stockholm University, Faculty of Science, Department of Botany.
    Borg-Karlson, Anna-Karin
    Kolb, Annette
    Selection on plant optical traits and floral scent: Effects via seed development and antagonistic interactions2012In: Basic and Applied Ecology, ISSN 1439-1791, E-ISSN 1618-0089, Vol. 13, no 6, p. 509-515Article in journal (Refereed)
    Abstract [en]

    Evolutionary explanations of plant reproductive traits have usually emphasized optical characteristics of plants and selection mediated by pollinators. In recent years, studies have been broadened by incorporating also interactions with antagonists and by studying plant fragrant cues. Here, we examined if optical and fragrance traits of the perennial herb Primula veris correlated with reproductive success, in terms of fruit and seed set, and with avoidance of seed predators. Selection path analysis showed that both optical and fragrance traits influenced total seed production, and effects occurred both via fruit and seed set and via predator avoidance. In one case the same trait, inflorescence height, influenced total seed production both positively and negatively through effects on different components of fitness. Our results lend support to the notion that selection by mutualists and antagonists simultaneously acts on optical and fragrance traits.

  • 160.
    Ehrlén, Johan
    et al.
    Stockholm University, Faculty of Science, Department of Botany.
    Münzbergova, Zuzana
    Timing of flowering - opposed selection on different fitness components and trait covariation2009In: American Naturalist, ISSN 0003-0147, E-ISSN 1537-5323, Vol. 173, p. 819-830Article in journal (Refereed)
  • 161.
    Ekengren, Sophia
    Stockholm University, Faculty of Science, Department of Botany. Stockholm University, Faculty of Science, Department of Botany. Växtfysiologi.
    Cutting the gordian knot: taking a stab at corky root rot of tomato2008In: Plant Biotechnology, ISSN 1342-4580, Vol. 25, no 3, p. 265-269Article in journal (Refereed)
  • 162.
    Eklöf, J.S.
    et al.
    Stockholm University, Faculty of Science, Department of Systems Ecology.
    Gullström, Martin
    Department of Zoology. Ekologi.
    Björk, Mats
    Department of Botany.
    Asplund, M.E.
    Hammar, L.
    Dahlgren, A.
    Öhman, Marcus
    Department of Zoology. Ekologi.
    The importance of grazing intensity and frequency for physiological responses of the tropical seagrass Thalassia hemprichii2008In: Aquatic botany, Vol. 89, p. 337-340Article in journal (Refereed)
    Abstract [en]

    Seagrass grazing is an intrinsic disturbance in primarily tropical and subtropical areas. While there is a general parabolic response in seagrass growth to grazing intensity, there is less knowledge on the role of grazing frequency, as well as potential interactions between grazing intensity and frequency. This study experimentally investigated physiological responses in Thalassia hemprichii to simulated (leaf cutting) grazing regimes with different intensities (25% vs. 75%) and frequencies (I times vs. 3 times) over 35 days in Chwaka Bay (Zanzibar, Tanzania). The results showed that the two high-intensity treatments (75% removal) had 37-41% lower growth rate than the low-intensity/low-frequency treatment, and rhizome sugar and starch content were both affected in a similar way. A 36% lower starch content in the simulated low-intensity/high-frequency regime (25% x 3) compared to the one of low-intensity/low-frequency (25% x I) also shows an interaction between grazing intensity and frequency. This suggests that high-intensity (and to some extent frequency) grazing regimes, in comparison to low-intensity regimes, could negatively affect T. hemprichii growth, energy reserves, and thereby the ability to deal with additional stress like light limitation or grazing.

  • 163.
    Ekman, Martin
    Stockholm University, Faculty of Science, Department of Botany.
    Cyanobacteria in symbiosis with plants: Protein patterns and regulatory mechanisms2005Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Cyanobacteria belonging to the heterocystous genus Nostoc, capable of oxygenic photosynthesis and nitrogen fixation via the enzyme nitrogenase, may form symbiotic associations with plants. In these associations most of the N2 fixed by the symbiotic cyanobacteria (cyanobiont) is transferred to the host, which in turn supplies the cyanobiont with fixed carbon. By using a proteomic approach adapted for investigating unsequenced organisms, adaptations of the cyanobiont to symbiotic conditions within the angiosperm Gunnera, for which each generation needs to be newly infected, and the water fern Azolla, which is in permanent association with its cyanobiont, were investigated.

    Despite morphological and physiological modifications of the cyanobionts, many basic functions appear to be intact in symbiosis compared to when free-living, as indicated by similar protein levels. Some differences were identified however, and in the view of parallel studies on photoautotrophic and heterotrophic growth of free-living cyanobacteria, these indicated that cellular functions were focused on N2 fixation and the associated heterocyst specific metabolism, and also reflected a mainly heterotrophic growth. Stress responses were induced in both cyanobionts, while surface adaptations mainly in that of Gunnera, possibly a reflection of its intracellular location in combination with the microaerobic and dark conditions inside the Gunnera glands. The heterocyst envelope was reduced, which may be involved in ammonia release. The level of nitrogenase was considerably higher in the Azolla cyanobiont, potentially reflecting a co-evolution with its host plant. The results also indicate that the Azolla cyanobiont may be classified as a new genus. Probably induced by oxygen, some nitrogenase in the Azolla cyanobiont carried a post-translational modification, located within a specific peptide corresponding to the part of nitrogenase that is ADP-ribosylated in certain other N2-fixing bacteria. However, the modification, with a mass of 300-400 Da, was not identified.

    The regulation behind heterocyst differentiation, N2-fixation and N-assimilation in symbiosis was also investigated. The mechanisms involving the regulatory proteins NtcA and HetR appear to be intact in symbiosis but distinctly upregulated, generating the higher heterocyst frequencies observed. This upregulation may be induced by a high C:N ratio in symbiosis or a plant effector molecule. These results also indicate that glutamine synthetase levels are reduced in symbiosis by a separate, but unknown mechanism. A sugar uptake regulator located near the hrm hormogonium repressing operon may be involved in carbohydrate uptake in the Gunnera symbiosis. Expression of isoenzymes of glyceraldehyde-3-phosphate dehydrogenase and fructose-1,6-bisphosphatase and a possible redox regulation of certain enzymes may be involved in regulation of metabolic pathways in symbiotic as well as in free-living cyanobacteria. Potential host-induced mechanisms responsible for cyanobiont adaptations, other than the environment offered in symbiosis, remain to be identified.

  • 164.
    Ekman, Martin
    et al.
    Stockholm University, Faculty of Science, Department of Botany.
    Tollbäck, Petter
    Bergman, Birgitta
    Mass spectrometric analysis of the nitrogen-fixing cyanobacterium of the Azolla symbiosis: adaptation and NifH modificationManuscript (Other academic)
  • 165. Ekman, Martin
    et al.
    Tollbäck, Petter
    Bergman, Birgitta
    Stockholm University, Faculty of Science, Department of Botany.
    Proteomic analysis of the cyanobacterium of the Azolla symbiosis: identity, adaptation, and NifH modification.2008In: J Exp Bot, ISSN 1460-2431, Vol. 59, no 5, p. 1023-34Article in journal (Refereed)
  • 166.
    Ekman, Martin
    et al.
    Stockholm University, Faculty of Science, Department of Botany.
    Tollbäck, Petter
    Department of Analytical Chemistry.
    Bergman, Birgitta
    Stockholm University, Faculty of Science, Department of Botany.
    Proteomic analysis of the cyanobacterium of the Azolla symbiosis: identity, adaptation, and NifH modification.2007In: J Exp Bot, ISSN 0022-0957Article in journal (Refereed)
  • 167.
    Ekman, Martin
    et al.
    Stockholm University, Faculty of Science, Department of Botany.
    Tollbäck, Petter
    Stockholm University, Faculty of Science, Department of Analytical Chemistry.
    Klint, Johan
    Stockholm University, Faculty of Science, Department of Botany.
    Bergman, Birgitta
    Stockholm University, Faculty of Science, Department of Botany.
    Protein expression profiles in an endosymbiotic cyanobacterium revealed by a proteomic approach2006In: Molecular Plant-Microbe Interactions, ISSN 0894-0282, E-ISSN 1943-7706, Vol. 19, no 11, p. 1251-1261Article in journal (Refereed)
    Abstract [en]

    Molecular mechanisms behind adaptations in the cyano-bacterium (Nostoc sp.) to a life in endosymbiosis with plants are still not clarified, nor are the interactions between the partners. To get further insights, the proteome of a Nostoc strain, freshly isolated from the symbiotic gland tissue of the angiosperm Gunnera manicata Linden, was analyzed and compared with the proteome of the same strain when free-living. Extracted proteins were separated by two-dimensional gel electrophoresis and were identified by matrix-assisted laser desorption/ionization-time of flight mass spectrometry combined with tandem mass spectrometry. Even when the higher percentage of differentiated cells (heterocysts) in symbiosis was compensated for, the majority of the proteins detected in the symbiotic cyanobacteria were present in the free-living counterpart, indicating that most cellular processes were common for both stages. However, differential expression profiling revealed a significant number of proteins to be down-regulated or missing in the symbiotic stage, while others were more abundant or only expressed in symbiosis. The differential protein expression was primarily connected to i) cell envelope-associated processes, including proteins involved in exopolysaccharide synthesis and surface and membrane associated proteins, ii) to changes in growth and metabolic activities (C and N), including upregulation of nitrogenase and proteins involved in the oxidative pentose phosphate pathway and downregu-lation of Calvin cycle enzymes, and iii) to the dark, micro-aerobic conditions offered inside the Gunnera gland cells, including changes in relative phycobiliprotein concentrations. This is the first comprehensive analysis of proteins in the symbiotic state.

  • 168.
    Eldenäs, Pia
    Stockholm University, Faculty of Science, Department of Botany.
    Phylogenetic studies in the Inuleae s. lat. (Asteraceae)1997Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    This thesis concerns phylogenetic problems in the tribe Inuleae s. lat. (Asteraceae). The genus Perralderia is revised. Fontquera is found to be taxonomically synonymous and is consequently included in Perralderia. Three species are recognised in this genus and their biogeography is briefly discussed. The result of a cladistic analysis of Perralderia and its presumed sister group Iphiona is presented. A cladistic analysis of the basal interrelationships of the Inuleae s. str. focussing on the morphological variation of the genus Anisopappus is presented. Anisopappus is found to be monophyletic and placed as the sister group to the rest of the tribe. A discussion of some floral characters is provided. The first molecular phylogeny of the Inuleae s. str. is presented, based on nrDNA ITS sequences. The result of the analysis is discussed and compared with analyses of morphological data. A strict consensus tree of the cladistic analysis is shown and serves as a base for the discussion of interpretations of the character evolution of e. g. receptacular paleae and pappus scales. The previously suggested subdivision of the tribe into an epaleate clade and a paleate grade is not supported. The systematic position of Cylindrocline and Rosenia is determined in a cladistic analysis of cpDNA ndhF data. The obtained sequences for the two genera are combined with additional GenBank data for 89 taxa of the Asteraceae as well as five outgroups, and analysed by parsimony jackknifing. The result is presented in a consensus tree. Cylindrocline is placed in the tribe Plucheeae and Rosenia is found to belong to Gnaphalieae. Tribal interrelationships of subfamily Asteroideae are discussed with emphasis on the affinities of the tribes Inuleae s. str., Plucheeae and Gnaphalieae.

  • 169. Elvebakk, Arve
    et al.
    Papaefthimiou, Dimitra
    Stockholm University, Faculty of Science, Department of Botany.
    Robertsen, Eli Helene
    Liaimer, Anton
    Phylogenetic patterns among Nostoc cyanobionts within Bi- and tripartite lichens of the genus Pannaria2008In: Journal of Phycology, ISSN 0022-3646, E-ISSN 1529-8817, Vol. 44, no 4, p. 1049-1059Article in journal (Refereed)
    Abstract [en]

    Phylogenetic relationships between Nostoc cyanobionts in the lichen genus Pannaria were studied to evaluate their correlation to geography, habitat ecology, and other patterns previously reported. The 16S rRNA gene sequences of a total of 37 samples of 21 Pannaria species from seven countries from the Northern and Southern hemispheres were analyzed and compared with 69 free-living and symbiotic cyanobacterial strains. The sequences from Pannaria were distributed throughout a branch of Nostoc sequences previously called ""the Nephroma guild,"" and within two subgroups from another branch, referred to as the ""Peltigera guild,"" although there was a gradual transition between the two major groups. There is a more diverse pattern of relationships between Nostoc sequences from bipartite versus tripartite lichen species in Pannaria, compared with other well-studied genera, such as Nephroma and Peltigera. Cyanobionts from several tripartite Pannaria species from the Southern Hemisphere and corticolous bipartite species from both hemispheres were grouped together. Four sequences of Pannaria and Pseudocyphellaria cyanobionts from rocks in the Chilean Juan Fernandez Islands were nested within corticolous cyanobionts, whereas the terricolous ""Pannaria sphinctrina clade"" was placed with other terricolous strains. The cluster patterns derived from phylogenetic analysis were partly reflecting lichen taxonomy, in two groups of lichen species, possibly indicating coevolution. The phylogram partly also reflected lichen ecology. Three Pannaria species have very different cyanobiont strains when they grow in different habitats.

  • 170. Emmanuelsson, Erik
    et al.
    Razafimandimbison, Sylvain
    Stockholm University, Faculty of Science, Bergianska botaniska trädgården (tills m Kungl. Vet. Ak.). Department of Botany. Plant Systematics.
    A new species of Gyrostipula (Rubiaceae, Naucleeae) from Madagascar2007In: Novon, ISSN 1055-3177, Vol. 17, no 4, p. 421-423Article in journal (Refereed)
  • 171.
    Engelen, Dries
    Stockholm University, Faculty of Science, Department of Botany.
    Comparing avifauna communities and bird functional diversity of forest and farmland in southwest Ethiopia2012Independent thesis Advanced level (degree of Master (Two Years)), 30 credits / 45 HE creditsStudent thesis
    Abstract [en]

    Worldwide degradation and conversion of tropical forests affects many species and their provided ecosystem services. Among them are birds, responsible for pollination, seed dispersal, pest control and scavenging. This study, conducted in southwest Ethiopia, compares species composition and bird functional diversity between forest and homegardens close to and far from forest, both in terms of species numbers and bird abundances. Point counts and mist netting were used to obtain data. While the former method detected more species, abundance data from the latter revealed patterns not observed by just comparing species numbers.

    I found that species diversity was lower in forest compared to gardens and that the species composition of both communities was significantly distinct. Whereas forest had more forest specialists, gardens held more forest visitors and species of open country. Close and far gardens did not differ in any aspect, except that abundances of forest generalist birds were somewhat higher close to forest. Regarding bird feeding guilds, I found that granivores and nectarivores were more numerous in gardens, while frugivores were more common in forest. Carnivores and omnivores showed no effect. Insectivore proportions were the same for forest and farmland, but their numbers (including those of all sub-guilds) were higher in gardens.

    The Ethiopian forest avifauna is poor in comparison with other Afromontane regions, lacking several, mostly insectivorous genera. This could be the result of an extinction after which its geographic isolation made recolonization difficult, especially for dispersal-limited understory species. Nonetheless, and despite their impoverished state, the results suggest that forest remnants are important for forest-dependent species, being a stronghold for forest specialists and supporting higher numbers of forest generalists in nearby gardens. However, future forest regrowth might be at stake with ongoing agricultural encroachment, because gardens hold fewer frugivores, especially forest specialists, which might affect seed dispersal.

  • 172. Englund, Göran
    et al.
    Hambäck, Peter A
    Stockholm University, Faculty of Science, Department of Botany. Växtekologi.
    Scale dependence of immigration rates: models, metrics and data.2007In: J Anim Ecol, ISSN 0021-8790, Vol. 76, no 1, p. 30-5Article in journal (Refereed)
    Abstract [en]

    1. We examine the relationship between immigration rate and patch area for different types of movement behaviours and detection modes. Theoretical models suggest that the scale dependence of the immigration rate per unit area (I/A) can be described by a power model I/A = i*Areaζ, where ζ describes the strength of the scale dependence.

    2. Three types of scaling were identified. Area scaling (ζ=0) is expected for passively dispersed organisms that have the same probability of landing anywhere in the patch. Perimeter scaling (−0·30>ζ>−0·45) is expected when patches are detected from a very short distance and immigrants arrive over the patch boundary, whereas diameter scaling (ζ=−0·5) is expected if patches are detected from a long distance or if search is approximately linear.

    3. A meta-analysis of published empirical studies of the scale dependence of immigration rates in terrestrial insects suggests that butterflies show diameter scaling, aphids show area scaling, and the scaling of beetle immigration is highly variable. We conclude that the scaling of immigration rates in many cases can be predicted from search behaviour and the mode of patch detection.

  • 173.
    Englund, Markus
    Stockholm University, Faculty of Science, Department of Botany.
    Clade size is not always an appropriate measure of diversification2011In: Proceedings of the National Academy of Sciences of the United States of America, ISSN 0027-8424, E-ISSN 1091-6490, Vol. 108, no 17, p. E84-E84Article in journal (Refereed)
  • 174.
    Englund, Markus
    et al.
    Stockholm University, Faculty of Science, Department of Botany.
    Pornpongrungrueng, Pimwadee
    Systematic Botany, Institute of Biological Sciences, University of Aarhus.
    Gustafsson, Mats H. G.
    Systematic Botany, Institute of Biological Sciences, University of Aarhus.
    Anderberg, Arne A.
    Stockholm University, Faculty of Science, Department of Botany.
    Phylogenetic relationships and generic delimitation in Inuleae subtribe Inulinae (Asteraceae) based on ITS and cpDNA sequence data2009In: Cladistics, ISSN 0748-3007, E-ISSN 1096-0031, Vol. 25, no 4, p. 319-352Article in journal (Refereed)
    Abstract [en]

    Phylogenetic relationships in Inuleae subtribe Inulinae (Asteraceae) were investigated. DNA sequence data from three chloroplast regions (ndhF,trnL–F and psbA–trnH) and the nuclear ribosomal internal transcribed spacer (ITS) region were analysed separately and in combination using parsimony and Bayesian inference. A total of 163 ingroup taxa were included, of which 60 were sampled for all four markers. Conflicts between chloroplast and nuclear data were assessed using partitioned Bremer support (PBS). Rather than averaging PBS over several trees from constrained searches, individual trees were considered by evaluating PBS ranges. Criteria to be used in the detection of a significant conflict between data partitions are proposed. Three nodes in the total data tree were found to encompass significant conflict that could result from ancient hybridization. Neither of the large, heterogeneous and widespread genera Inula and Pulicaria is monophyletic. A monophyletic group ("the Inula complex") that comprises all species of Inula include also Telekia, Carpesium, Chrysophthalmum, Rhanteriopsis, Amblyocarpum, and Pentanema sensu stricto. Two species of Pentanema were found to be closer to Blumea (including Blumeopsis and Merrittia) and Caesulia. The monophyletic "Pulicaria complex" includes all taxa with heteromorphic pappus. Within this group, Francoeuria is distinct from Pulicaria and merits recognition as a separate genus.

  • 175.
    Eriksson, Britas Klemens
    et al.
    Stockholm University, Faculty of Science, Department of Systems Ecology.
    Ljunggren, Lars
    Swedish Board Fisheries.
    Sandström, Alfred
    Swedish Board Fisheries.
    Johansson, Gustav
    Fdn Uppland.
    Mattila, Johanna
    Åbo Akad Univ.
    Rubach, Anja
    Univ Cologne.
    Råberg, Sonja
    Stockholm University, Faculty of Science, Department of Botany.
    Snickars, Martin
    Åbo Akad Univ.
    Declines in predatory fish promote bloom-forming macroalgae.2009In: Ecological Applications, ISSN 1051-0761, E-ISSN 1939-5582, Vol. 19, no 8, p. 1975-1988Article in journal (Refereed)
    Abstract [en]

    In the Baltic Sea, increased dominance of ephemeral and bloom-forming algae is presently attributed to increased nutrient loads. Simultaneously, coastal predatory fish are in strong decline. Using field data from nine areas covering a 700-km coastline, we examined whether formation of macroalgal blooms could be linked to the composition of the fish community. We then tested whether predator or nutrient availability could explain the field patterns in two small-scale field experiments, by comparing joint effects on algal net production from nutrient enrichment with agricultural fertilizer and exclusion of larger predatory fish with cages. We also manipulated the presence of invertebrate grazers.

    The abundance of piscivorous fish had a strong negative correlation with the large-scale distribution of bloom-forming macroalgae. Areas with depleted top-predator communities displayed massive increases in their prey, small-bodied fish, and high covers of ephemeral algae. Combining the results from the two experiments showed that excluding larger piscivorous fish: (1) increased the abundance of small-bodied predatory fish; (2) changed the size distribution of the dominating grazers, decreasing the smaller gastropod scrapers; and (3) increased the net production of ephemeral macroalgae. Effects of removing top predators and nutrient enrichment were similar and additive, together increasing the abundance of ephemeral algae many times. Predator effects depended on invertebrate grazers; in the absence of invertebrates there were no significant effects of predator exclusion on algal production. Our results provide strong support for regional declines of larger predatory fish in the Baltic Sea promoting algal production by decreasing invertebrate grazer control. This highlights the importance of trophic interactions for ecosystem responses to eutrophication. The view emerges that to achieve management goals for water quality we need to consider the interplay between top-down and bottom-up processes in future ecosystem management of marine resources.

  • 176. Eriksson, Britas Klemens
    et al.
    van Sluis, Christiaan
    Sieben, Karin
    Kautsky, Lena
    Stockholm University, Faculty of Science, Department of Botany.
    Råberg, Sonja
    Stockholm University, Faculty of Science, Department of Botany.
    Omnivory and grazer functional composition moderate cascading trophic effects in experimental Fucus vesiculosus habitats2011In: Marine Biology, ISSN 0025-3162, E-ISSN 1432-1793, Vol. 158, no 4, p. 747-756Article in journal (Refereed)
    Abstract [en]

    We tested the relative strength of direct versus indirect effects of an aquatic omnivore depending on the functional composition of grazers by manipulating the presence of gastropod and amphipod grazers and omnivorous shrimp in outdoor mesocosms. By selectively preying upon amphipods and reducing their abundance by 70-80%, omnivorous shrimp favoured the dominance of gastropods. While gastropods were the main microalgal grazers, amphipods controlled macroalgal biomass in the experiment. However, strong predation on the amphipod by the shrimp had no significant indirect effects on macroalgal biomass, indicating that when amphipod abundances declined, complementary feeding by the omnivore on macroalgae may have suppressed a trophic cascade. Accordingly, in the absence of amphipods, the shrimp grazed significantly on green algae and thereby suppressed the diversity of the macroalgal community. Our experiment demonstrates direct consumer effects by an omnivore on both the grazer and producer trophic levels in an aquatic food web, regulated by prey availability.

  • 177.
    Eriksson, Johan
    Stockholm University, Faculty of Science, Department of Botany.
    Protein concentration versus derivatization efficiency2007In: 4th Symposium “BMAA - occurrence and potential threat to human health”, Stockholm 2007, 2007Conference paper (Other (popular science, discussion, etc.))
  • 178.
    Eriksson, Johan
    et al.
    Stockholm University, Faculty of Science, Department of Botany.
    Jonasson, Sara
    Stockholm University, Faculty of Science, Department of Botany.
    Papaefthimiou, Dimitra
    Rasmussen, Ulla
    Bergman, Birgitta
    Improving derivatization efficiency of BMAA utilizing AccQ-Tag ia a complex cyanobacterial matrix2009In: Amino Acids, ISSN 0939-4451, E-ISSN 1438-2199, no 36, p. 43-48Article in journal (Refereed)
    Abstract [en]

    Two different assays have been developed and used in order to investigate the optimal conditions for derivatization and detection of acid β-N-methyl-amino-l-alanine (BMAA) in a cyanobacterial sample. BMAA was extracted from cyanobacterial cultures both from the cytosolic (“free”) fraction and in the precipitated (“protein”) fraction using a newly developed extraction scheme and the sample matrix was standardized according to protein concentration to ensure the highest possible derivative yield. A rapid and sensitive HPLC method for fluorescence detection of the non-protein amino acid BMAA in cyanobacteria, utilizing the Waters AccQ-Tag® chemistry and Chromolith® Performance RP-18e columns was developed. Using this new method and utilizing a different buffer system and column than that recommended by Waters, we decreased the time between injections by 75%. The limit of quantification was determined to be 12 nmol and limit of detection as 120 fmol. The linear range was in the range of 8.5 nmol–84 pmol. Accuracy and precision were well within FDA guidelines for bioanalysis.

  • 179.
    Eriksson, Ove
    Stockholm University, Faculty of Science, Department of Botany.
    A closer look at the species behind abundance-occupancy relationships2013In: Journal of Vegetation Science, ISSN 1100-9233, E-ISSN 1654-1103, Vol. 24, no 4, p. 589-590Article in journal (Refereed)
    Abstract [en]

    Guedo & Lamb (), in this issue of the Journal of Vegetation Science, used a 35-yr data series from two prairie communities to show that abundance-occupancy relationships change over time. Scrutinizing the details behind this finding, they show that species groups follow different trajectories during succession after disturbance. These results will inspire further species-level studies unraveling mechanisms behind abundance-occupancy relationships.

  • 180.
    Eriksson, Ove
    Stockholm University, Faculty of Science, Department of Botany. Växtekologi.
    Evolution of seed size and biotic seed dispersal in angiosperms: paleoecological and neoecological evidence2008In: International Journal of Plant Sciences, Vol. 169, p. 863-870Article in journal (Refereed)
  • 181.
    Eriksson, Ove
    Stockholm University, Faculty of Science, Department of Botany. Växtekologi.
    Naturbetesmarkernas växter: Ekologi, artrikedom och bevarandebiologi2007Report (Other (popular science, discussion, etc.))
  • 182.
    Eriksson, Ove
    Stockholm University, Faculty of Science, Department of Botany.
    Niche shifts and seed limitation as mechanisms determining seedling recruitment in clonal plants2011In: Preslia (Praha), ISSN 0032-7786, Vol. 83, no 3, p. 301-314Article in journal (Refereed)
    Abstract [en]

    This is a review of the evidence on seedling recruitment patterns in clonal forest plants, based on a previously used typology in which the occurrence of seedling recruitment is related to the performance of adult genets: repeated seedling recruitment (RSR), initial seedling recruitment (ISR), recruitment at windows of opportunity (RWO) and systematic spatial variation in seedling dynamics among local populations (RSR/ISR). Generally, seedling recruitment in clonal populations is common and the majority of species have the capacity to recruit within established adult populations. All four recruitment patterns are documented in studies, which include both genetic and demographic evidence that support the existence of a range of variation in seedling recruitment among clonal plants. However, it is suggested that this four-category typology should be replaced by a framework based on two continuously varying factors: the degree of niche overlap between juvenile and adult life cycle stages (uncoupling of juvenile and adult niches implies niche shifts) and of seed limitation during recruitment. This creates a hypothetical continuous space within which all recruitment patterns are placed and stimulates research to focus on identifying mechanisms determining the variation in the recruitment of clonal plants. Some further implications of this framework are briefly discussed.

  • 183.
    Eriksson, Ove
    Stockholm University, Faculty of Science, Department of Botany.
    Species pools in cultural landscapes - niche construction, ecological opportunity and niche shifts2013In: Ecography, ISSN 0906-7590, E-ISSN 1600-0587, Vol. 36, no 4, p. 403-413Article, review/survey (Refereed)
    Abstract [en]

    This paper discusses the ecology of species that were favoured by the development of the cultural landscape in central and NW Europe beginning in the Neolithic and the Bronze Age, with a focus on mechanisms behind species responses to this landscape transformation. A fraction of species may have maintained their realized niches from the pre- agricultural landscape and utilized similar niches created by the landscape transformation. However, I suggest that many species responded by altering their niche relationships, and a conceptual model is proposed for this response, based on niche construction, ecological opportunity and niche shifts. Human-mediated niche construction, associated with clearing of forests and creation of pastures and fields promoted niche shifts towards open habitats, and species exploited the ecological opportunity provided by these created environments. This process was initially purely ecological, i.e. the new habitats must have been included in the original fundamental niche of the species. Two other features of human-mediated niche construction, increased interconnectivity and increased spatial stability of open habitats, resulted in species accumulating in the habitats of the constructed landscape. As a consequence, selection processes were initiated favouring traits promoting fitness in the constructed landscape. This process implied a feed-back to niche shifts, but now also including evolutionary changes in fundamental niches. I briefly discuss whether this model can be applied also to present-day anthropogenic impact on landscapes. A general conclusion is that ecological and evolutionary changes in species niches should be more explicitly considered in modeling and predictions of species response to present-day landscape and land-use changes.

  • 184.
    Eriksson, Ove
    et al.
    Stockholm University, Faculty of Science, Department of Botany.
    Cousins, Sara A. O.
    Stockholm University, Faculty of Science, Department of Physical Geography and Quaternary Geology.
    Bruun, Hans Henrik
    Stockholm University, Faculty of Science, Department of Botany.
    Land-use history and fragmentation of traditionally managed grasslands in Scandinavia2002In: Journal of Vegetation Science, ISSN 1100-9233, E-ISSN 1654-1103, Vol. 13, no 5, p. 743-748Article in journal (Refereed)
    Abstract [en]

    Plants associated with traditional agricultural landscapes in northern Europe and Scandinavia are subjected to drastic habitat fragmentation. In this paper we discuss species response to fragmentation, against a background of vegetation and land-use history. Recent evidence suggests that grassland-forest mosaics have been prevalent long before the onset of human agriculture. We suggest that the creation of infield meadows and outland grazing (during the Iron Age) increased the amount and spatial predictability of grasslands, resulting in plant communities with exceptionally high species densities. Thus, distribution of plant species in the present-day landscape reflects historical land-use. This holds also when traditional management has ceased, due to a slow response by many species to abandonment and fragmentation. The distribution patterns are thus not in equilibrium with the present habitat distribution. Fragmentation influences remaining semi-natural grasslands such that species density is likely to decline as a result of local extinctions and invasion by habitat generalists. However, species that for a long time have been subjected to changing mosaic landscapes may be more resistant to fragmentation than is usually believed. Conservation should focus not only on 'hot-spots' with high species richness, but also consider species dynamics in a landscape context.

  • 185.
    Eriksson, Ove
    et al.
    Stockholm University, Faculty of Science, Department of Botany. Växtekologi.
    Ehrlén, Johan
    Stockholm University, Faculty of Science, Department of Botany. Växtekologi.
    Seedling recruitment and population ecology2008In: Seedling Ecology and Evolution, Cambridge University Press, Cambridge , 2008, p. 239-254Chapter in book (Refereed)
  • 186.
    Eriksson, Ove
    et al.
    Stockholm University, Faculty of Science, Department of Botany.
    Kainulainen, Kent
    Stockholm University, Faculty of Science, Department of Botany.
    The evolutionary ecology of dust seeds2011In: Perspectives in plant ecology, evolution and systematics, ISSN 1433-8319, E-ISSN 1618-0437, Vol. 13, no 2, p. 73-87Article, review/survey (Refereed)
    Abstract [en]

    Dust seeds are the smallest existing seeds in angiosperms. This paper summarizes taxonomic distribution, phylogeny, ontogeny, morphology, and recruitment behavior of dust seeds, concluding with a general hypothesis on the evolution of dust seeds. Plants with dust seeds depend on external sources of organic carbon for seedling development and are thus parasitic during recruitment. Species with dust seeds are either mycoheterotrophic (fully or partially) or parasitic on plants. Dust seeds are a derived feature which has evolved independently in at least 12 families (Burmanniaceae, Corsiaceae, Orchidaceae, Triuridaceae, Petrosaviaceae, Ericaceae, Gentianaceae, Polygalaceae, Orobanchaceae, Rubiaceae, Buddlejaceae and Gesneriaceae). For the three latter families parasitic behavior during recruitment has not yet been described, and should be considered as a hypothesis. Many, but not all, dust seeds possess features that are likely to have been selected for increasing buoyancy in air or water. Selection for maximal fecundity at the expense of reducing maternal resources per seed is the probable driver of dust seed evolution. As endosperm was reduced, undifferentiated embryo evolved as a by-product due to endosperm mediated control of embryo development. Ultimately, seed size reduction passed a threshold where resource acquisition became dependent on external hosts. In order to embark on an evolutionary trajectory towards host dependence, facultative parasitism must have been established in ancestral lineages. Mycoheterotrophic and mixotrophic plants probably evolved along with the rise of angiosperm dominated tropical forests beginning in the Late Cretaceous. It is suggested that selection for increasing seed size associated with the expansion of modern type tropical forests spurred a competition/colonization trade-off initiating a reversed evolutionary trajectory towards smaller seeds. A different process is suggested for true parasites with dust seeds (Orobanchaceae), where the driver may have been the Mid-Tertiary expansion of grasslands, creating opportunities to exploit grasses and herbs. It is suggested that inequality and asymmetry in resource monopolization in ecosystems promote evolution of subordinate life strategies, and possession of dust seeds is considered as a subordinate strategy in plant communities dominated by other plant strategies. This escape route for ecological losers eventually promoted evolution of one of the most diverse groups of plants, the orchids.

  • 187.
    Eriksson, Ove
    et al.
    Stockholm University, Faculty of Science, Department of Botany.
    Persson, Lennart
    Umeå university.
    A spatial dimension of ecology: Ilkka Hanski Crafoord Laureate2011In: Ambio, ISSN 0044-7447, E-ISSN 1654-7209, ISSN 0044-7447, Vol. 40, no 3, p. 247-247Article in journal (Refereed)
  • 188.
    Eriksson, Torsten
    Stockholm University, Faculty of Science, Department of Botany.
    Systematics and phylogenetics of the Blepharispermum group (Asteraceae - Heliantheae)1993Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    This thesis treats the Blepharispermum group which comprises the three genera Athroisma DC., Blepharispermum Wight ex DC., and Leucoblepharis Arnott. The systematic position of the group within the Asteraceae is discussed, and a transfer is proposed from the tribe Inuleae, where it was placed earlier, to the Heliantheae. The subtribal position within the Heliantheae is also discussed. A dadisric analysis of all species shows that the genera are monophyletic. The genus Leucoblepharis is reinstated for the sister species of Blepharispermum. Each genus is treated in more detail and nomenclature, taxonomy, morphology, distribution maps, and phylogenetic analyses are presented. In Blepharispermum, 15 species are accepted of which two are new, and in Athroisma 12 species are accepted of which four are new. In Athroisma, where intermediate collections abound, the correlation of character patterns with geographical distributions is investigated. Introgressive hybridisation is hypothesised to account for the presence of four intermediate ”groups” of specimens. The relationships, taxonomic status, and origin of those groups are discussed.

  • 189. Eriksson, Torsten
    et al.
    Lundberg, Magnus
    Stockholm University, Faculty of Science, Department of Botany.
    Topel, Mats
    Östensson, Pia
    Stockholm University, Faculty of Science, Department of Botany.
    Smedmark, Jenny E. E.
    Sibbaldia: a molecular phylogenetic study of a remarkably polyphyletic genus in Rosaceae2015In: Plant Systematics and Evolution, ISSN 0378-2697, E-ISSN 1615-6110, Vol. 301, no 1, p. 171-184Article in journal (Refereed)
    Abstract [en]

    Using DNA sequence data from nuclear ribosomal ITS in combination with plastid trnLF spacer and trnL intron data, we show that Sibbaldia is a polyphyletic assemblage. It falls into five separate clades of Potentilleae, three within Fragariinae and two within Potentilla (Potentillinae sensu Sojak). To a large extent, our results are congruent with Sojak's findings based on morphological characters such as anther structure. Four of the Sibbaldia species included in this study remain in Sibbaldia, while S. adpressa is classified in Sibbaldianthe, S. perpusilloides is considered to represent a new genus in Fragariinae, Chamaecallis Smedmark, S. micropetala is nested within the Potentilla anserina clade, and four species belong to a basal clade of Potentilla. The phylogenetic affinity of Sibbaldiopsis is still unsettled, but one of the three species that have been classified in the genus is found to belong inside Sibbaldia, and it should be named Sibbaldia retusa (O.F. Muller) T. Erikss. Further study will show whether the remaining two species, Potentilla cuneifolia and P. miyabei, are more closely related to Sibbaldia, Sibbaldianthe, or if they make up a distinct lineage separate from either of these.

  • 190. Eriksson, Torsten
    et al.
    Lundberg, Magnus
    Stockholm University, Faculty of Science, Department of Botany.
    Östensson, Pia
    Töpel, Mats
    Sibbaldia – a molecular phylogenetic study of a polyphyletic genus in RosaceaeManuscript (preprint) (Other academic)
    Abstract [en]

    Using DNA sequence data from nuclear ribosomal ITS in combination with plastid trnLF spacer and trnL intron data we show that Sibbaldia is a polyphyletic assemblage. It falls into five separate clades of Potentilleae, three within Fragariinae, and two within Potentilla (Potentillinae sensu Soják). In the main, our phylogenetic results agree with the findings by Soják (2008) which were based on anther structure. Four of our sampled Sibbaldia species remain in Sibbaldia, one [adpressa] is classified in Sibbaldianthe, one species [perpusilloides] is considered to represent an undescribed genus in Fragariinae, one [micropetala] is nested within the Potentilla anserina clade, and four species belong in a basal clade of Potentilla. Sibbaldiopsis is very close to Sibbaldia, and its single species should be named Sibbaldiopsis retusa (O.F. Müller) T. Erikss. and M. Lundberg.

  • 191. Falcon, Luisa I
    et al.
    Lindwall, Susanne
    Stockholm University, Faculty of Science, Department of Botany. Växtfysiologi.
    Bauer, Karolina
    Stockholm University, Faculty of Science, Department of Botany. Växtfysiologi.
    Bergman, Birgitta
    Stockholm University, Faculty of Science, Department of Botany. Växtfysiologi.
    Carpenter, Edward C
    Ultrastructure of unicellular N-2 fixing cyanobacteria from the tropical North Atlantic and subtropical North Pacific Oceans2004In: Journal of Phycology, Vol. 40, no 6, p. 1074-1078Article in journal (Refereed)
    Abstract [en]

    Abstract: Nitrogen fixing unicellular marine cyanobacteria may have a major role in the global biogeochemistry of N; nevertheless, little is known about their phylogeny and morphology. We isolated N-2 fixing unicellular cyanobacteria from the tropical North Atlantic and subtropical North Pacific Oceans and examined ultrastructural dynamics during dark:light cycles when grown in incubators. The isolate from the subtropical North Pacific was larger and showed a size variation from 3 to 7 mum but had similar morphology and cell division-plane characteristics as the isolate from the North Atlantic (2.5 mum). Nitrogen fixation only occurred during the dark phase, and ultrastructural analysis demonstrated changes in the appearance and quantity of large carbohydrate-like granules present in the cells. To verify the composition of these carbohydrate-like granules, staining with periodic acid, thioacetic acid, and silver was carried out, and a positive reaction was obvious in all cells. The cells from the Atlantic seemed to empty their polysaccharide granules during the night, whereas those from the Pacific showed a decrease in the number of their granules. Our work suggests that phylogenetically related strains of unicellular N-2 fixing cyanobacteria from different oceans showed similar carbohydrate-like granules that could be used to fuel N-2 fixation during darkness.

  • 192. Faltmarsch, Rasmus
    et al.
    Osterholm, Peter
    Greger, Maria
    Stockholm University, Faculty of Science, Department of Botany.
    Astrom, Mats
    Metal concentrations in oats (Avena sativa L.) grown on acid sulphate soils2009In: Agricultural and Food Science, ISSN 1459-6067, E-ISSN 1795-1895, Vol. 18, no 1, p. 45-56Article in journal (Refereed)
    Abstract [en]

    The aim of the study was to investigate the impact of soil chemistry on the concentrations of Co, Ni, Zn, Mn, Cu and Fe in oats (Avena saliva L. cv. Fiia) grown on Finnish acid sulphate (AS) soils with varying geochemical characteristics. Twenty two soil profiles, which were sampled to a depth of 1 m (five 20 cm section splits), and 26 composite oat grain samples were collected on a total of five fields. The concentrations of Co, Ni, Zn and Mn in the grains were correlated with the NH4Ac-EDTA-extractable concentrations in the soils. However, as these four chalcophilic metals are in general easily lost to drains and not retained as a large pool in the soil in easily-extractable form, also the concentrations in the oats were not in general elevated as compared with average values on other soils. On one of the fields, however, the Co and Ni concentrations in the soil, and thus also in the oats, were clearly elevated. Copper and Fe displayed no correlation between the soil and oat concentrations, indicating that the plant-uptake mechanisms are much more important than variations in geochemistry. It was suggested that the NH4Ac-EDTA solution was not efficient in extracting Fe and Cu, which shows that these metals are bound in relatively immobile oxyhydroxides.

  • 193.
    Ferm, Julia
    et al.
    Stockholm University, Faculty of Science, Department of Botany. Uppsala University, Sweden.
    Karehed, Jesper
    Bremer, Birgitta
    Stockholm University, Faculty of Science, Department of Botany. Royal Swedish Academy of Sciences, Sweden.
    Razafimandimbison, Sylvain G.
    Paracarphalea, a new genus of the coffee family segregated from the Malagasy endemic genus Carphalea (Rubiaceae, Rubioideae, Knoxieae)2016In: Phytotaxa, ISSN 1179-3155, E-ISSN 1179-3163, Vol. 263, no 2, p. 98-112Article in journal (Refereed)
    Abstract [en]

    The Malagasy genus Carphalea (Rubiaceae) consists of six species (C. angulata, C. cloiselii, C. kirondron, C. linearifolia, C. madagascariensis, C. pervilleana) of shrubs or small trees and is recognizable by a distinctly lobed calyx, 2(-4)-locular ovaries, each locule with several ovules on a rod-like stalk arising from the base of the locule, and indehiscent fruits. Carphalea linearifolia, rediscovered in 2010, has not previously been included in any Rubiaceae molecular phylogenetic studies. We re-investigated the monophyly of Carphalea using sequence data from chloroplast (rps16 and trnT-F) and nuclear (ITS and ETS) markers analysed with parsimony and Bayesian methods. Carphalea linearifolia forms a clade with C. cloiselii and the type species C. madagascariensis. This clade is sister to a clade consisting of the rest of the Carphalea species plus the genus Triainolepis. According to these results, the new genus Paracarphalea is here described to accommodate Carphalea angulata, C. kirondron, and C. pervilleana. The conservation status of Carphalea linearifolia is assessed as critically endangered according to IUCN criteria.

  • 194. Fior, Simone
    et al.
    Karis, Per Ola
    Stockholm University, Faculty of Science, Department of Botany.
    Phylogeny, evolution and systematics of Moehringia (Caryophyllaceae) as inferred from molecular and morphological data: a case of homology re-assessment2007In: Cladistics, Vol. 23, no 1, p. 1-11Article in journal (Refereed)
  • 195. Flores, Olivier
    et al.
    Garnier, Eric
    Wright, Ian J.
    Reich, Peter B.
    Pierce, Simon
    Diaz, Sandra
    Pakeman, Robin J.
    Rusch, Graciela M.
    Bernard-Verdier, Maud
    Testi, Baptiste
    Bakker, Jan P.
    Bekker, Renee M.
    Cerabolini, Bruno E. L.
    Ceriani, Roberta M.
    Cornu, Guillaume
    Cruz, Pablo
    Delcamp, Matthieu
    Dolezal, Jiri
    Eriksson, Ove
    Stockholm University, Faculty of Science, Department of Botany.
    Fayolle, Adeline
    Freitas, Helena
    Golodets, Carly
    Gourlet-Fleury, Sylvie
    Hodgson, John G.
    Brusa, Guido
    Kleyer, Michael
    Kunzmann, Dieter
    Lavorel, Sandra
    Papanastasis, Vasilios P.
    Perez-Harguindeguy, Natalia
    Vendramini, Fernanda
    Weiher, Evan
    An evolutionary perspective on leaf economics: phylogenetics of leaf mass per area in vascular plants2014In: Ecology and Evolution, ISSN 2045-7758, E-ISSN 2045-7758, Vol. 4, no 14, p. 2799-2811Article in journal (Refereed)
    Abstract [en]

    In plant leaves, resource use follows a trade-off between rapid resource capture and conservative storage. This worldwide leaf economics spectrum consists of a suite of intercorrelated leaf traits, among which leaf mass per area, LMA, is one of the most fundamental as it indicates the cost of leaf construction and light-interception borne by plants. We conducted a broad-scale analysis of the evolutionary history of LMA across a large dataset of 5401 vascular plant species. The phylogenetic signal in LMA displayed low but significant conservatism, that is, leaf economics tended to be more similar among close relatives than expected by chance alone. Models of trait evolution indicated that LMA evolved under weak stabilizing selection. Moreover, results suggest that different optimal phenotypes evolved among large clades within which extremes tended to be selected against. Conservatism in LMA was strongly related to growth form, as were selection intensity and phenotypic evolutionary rates: woody plants showed higher conservatism in relation to stronger stabilizing selection and lower evolutionary rates compared to herbaceous taxa. The evolutionary history of LMA thus paints different evolutionary trajectories of vascular plant species across clades, revealing the coordination of leaf trait evolution with growth forms in response to varying selection regimes.

  • 196.
    Fors, Lisa
    Stockholm University, Faculty of Science, Department of Botany.
    Interactions and Coevolution in Tritrophic systems2012Report (Other academic)
    Abstract [en]

    Ecological systems are usually complex, with a number of interacting species. These species interactions are commonly divided into two major groups: mutualistic and antagonistic. If the interactions are mutualistic, they are beneficial for all species involved, as in specialized relationships between certain plants and their pollinators. Antagonistic interactions, on the other hand, can be either competitive or trophic. Trophically interacting species are for example plants and their associated herbivores, predators and their prey or parasites and their hosts. In many of these interactions, some species are depending on others in order to survive. If one species changes, other species associated to it may have to adapt to the changes. This may lead to a process of reciprocal evolution between the interacting species, called coevolution. In this paper I start with a brief background on coevolution and local adaptation, and then describe some interactions in tritrophic systems. The tritrophic systems I focus on consist of plants, herbivore insects and parasitoids. I discuss some processes and mechanisms in these systems, such as host search, plant defense and the immune response in insects. In the end of the paper, a short description of my PhD-project is included.

  • 197. Forsberg, Lovisa
    et al.
    Kleja, Dan
    Greger, Maria
    Stockholm University, Faculty of Science, Department of Botany.
    Ledin, Stig
    Effects of sewage sludge on solution chemistry and plant uptake of Cu in sulphide mine tailings at different weathering stages2009In: Applied Geochemistry, ISSN 0883-2927, E-ISSN 1872-9134, Vol. 24, no 3, p. 475-482Article in journal (Refereed)
    Abstract [en]

    This climate chamber experiment examines the effects of sewage sludge (SS) on sulphide mine tailings from the Aitik Cu mine in northern Sweden. The effects of SS were determined from Cu in solution and Cu uptake and growth of plants on tailings showing 3 different degrees of weathering. Possible relationships between Cu content in plants and Cu in solution measured in tailings (total dissolved Cu and free Cu) were also evaluated. Red fescue (Festuca rubra) was grown for 6 weeks in pots of the different tailings treated with SS or NPK fertiliser. Soil solution was sampled with Rhizon tension lysimeters and analysed for pH, dissolved organic C (DOC), free Cu, total dissolved Cu and SO42-. The effects of SS on Cu in solution and plants depended on the degree of weathering. In tailings with a low degree of sulphide oxidation, SS application resulted in increased solubility and shoot accumulation of Cu compared with NPK-treated tailings, probably due to DOC forming soluble complexes with Cu. Sewage sludge also seemed to promote translocation of Cu to shoots in those tailings. In highly weathered tailings, lower contents of total dissolved Cu and free Cu in solution and lower Cu levels in shoots were found in SS-treated samples than in NPK-treated. In the moderately weathered tailings, Cu concentrations in solutions were generally similar between treatments, but lower contents of Cu were found in shoots and roots of the fescue grown in the SS-treatment. Irrespective of degree of weathering and treatment, both free Cu and total dissolved Cu concentration in tailings correlated strongly with Cu levels found in fescue shoots.

  • 198.
    Forslund, Helena
    Stockholm University, Faculty of Science, Department of Botany.
    Grazing and the geographical range of seaweeds: The introduced Fucus evanescens and the newly described Fucus radicans2009Licentiate thesis, monograph (Other academic)
    Abstract [en]

    Along the coast of temperate oceans brown algae of the genus Fucus form dense stands on rocky shores and are keystone species of the coastal ecosystem. These large seaweeds are perennial and function as substrate for many sessile marine organisms, provide shelter for fauna and juvenile fish, and are food source. A number of abiotic (e.g. wave-exposure, salinity and substrate) and biotic (e.g. herbivory and competition) factors structures these communities and determines the abundance and composition of fucoids at each specific site. Earlier studies have shown that herbivores may reduce growth of fucoids, thus affecting their distribution, and at high densities eliminate the species from previously occupied sites. In my thesis I focused on investigating herbivore-seaweed interactions and whether such interactions could influence the geographical range limits of Fucus species. A set of laboratory bioassays and a field survey were conducted (1) to investigate the resistance to grazing by a generalist gastropod between introduced (to Sweden) and native (Iceland) Fucus evanescens (Paper I),  (2) to study the distribution pattern of F. radicans and F. vesiculosus along the Swedish coast and specifically the southern limit of F. radicans, (3) to examine the abundance of herbivores in these two species, and (4) to test the hypothesis that Idotea baltica may contribute to restrict F. radicans to the Bothnian Sea (objective 2-4; Paper II). Fucus evanescens, a species that was introduced to the Swedish coast about 100 years ago, was found to be more resistant to grazing by L. littorea compared to F. evanescens from the native Icelandic populations.  It was also shown to contain a higher amount of phlorotannins; a putative chemical defence to herbivory. This indicates that development of resistance to herbivory could be important for a successful introduction and survival in a new range. No gradual change in the proportion, measured as % cover of either F. radicans or F. vesiculosus was found inside the range of F. radicans and its southernmost limit was abrupt without any corresponding abrupt change in any abiotic factor, e.g. salinity. Herbivores, i.e. Idotea spp., Gammarus spp. and Theodoxus fluviatils were found to be more abundant in F. radicans than in F. vesiculosus thalli indicating a habitat preference for F. radicans.  Further, Idotea baltica, whose range only overlaps with that of F. radicans in the south, was shown to prefer F. radicans over F. vesiculosus, possibly due to its lower content of phlorotannins. Based on these findings I propose that Idotea species may contribute in restricting the southern range of F. radicans, although further experiments, especially regarding competition with the larger F. vesiculosus need to be performed. In conclusion, biotic interactions e.g. the ability of to resist herbivore grazing by e.g. high phlorotannin content or having a structure less attractive as habitat to herbivores may be of importance in determining the geographic range of fucoids.

  • 199.
    Forslund, Helena
    Stockholm University, Faculty of Science, Department of Botany.
    Herbivory, phenotypic variation, and reproductive barriers in fucoids2012Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Along the shores of the Northern hemisphere Fucus (Phaeophyceae) species are a prominent presence, providing substrate, shelter, and food for many species. Fucus evanescens, a non-indigenous species (NIS) in Sweden, and F. radicans, a recently described species that so far has only been found inside the species poor Baltic Sea, are the focus of this thesis.

    Interactions with enemies (e.g. predators, herbivores, parasites) have been shown to play a role in the success of NIS. The low consumption of Fucus evanescens by the generalist gastropod Littorina littorea in Sweden was found to depend on high levels of chemical defense in the introduced population, not the failure of the herbivore to recognize F. evanescens as suitable food.

    A survey of the relative abundance of F. radicans and F. vesiculosus and the most common associated fauna along the Swedish Bothnian Sea coast showed that F. radicans and F. vesiculosus are equally abundant throughout the range of F. radicans. The most common associated fauna were found to be more abundant on F. radicans compared to F. vesiculosus.  In Sweden, where F. radicans had lower levels of defense chemicals than F. vesiculosus, F. radicans was grazed more than F. vesiculosus in bioassays. This could, together with other factors, influence the range of F. radicans.

    Fucus radicans and F. vesiculosus are closely related, recently separated, and growing sympatrically, therefore, possible reproductive barriers between F. radicans and F. vesiculosus were studied. In Estonia F. radicans and F. vesiculosus reproduces at different times of the year. No such clear reproductive barrier was found between the two species in Sweden where they reproduce at the same time and fertilization success and germling survival were the same for hybrids as for F. vesiculosus.

    Since the high clonality of F. radicans means that the gentic diversity in F. radicans populations is low I investigated how genetic diversity translates to phenotypic diversity in nine traits. Phlorotannin levels, recovery after desiccation, and recovery after freezing showed inherited variation, while the other six traits showed no variation related to genetic diversity. Phenotypic variation in populations of F. radicans will be higher in populations with higher genetic diversity and this might be beneficial to the community.

  • 200.
    Forslund, Helena
    et al.
    Stockholm University, Faculty of Science, Department of Botany.
    Eriksson, Ove
    Stockholm University, Faculty of Science, Department of Botany.
    Kautsky, Lena
    Stockholm University, Faculty of Science, Department of Botany.
    Grazing and geographic range of the Baltic seaweed Fucus radicans (Phaeophyceae)2012In: Marine Biology Research, ISSN 1745-1000, E-ISSN 1745-1019, Vol. 8, no 4, p. 322-330Article in journal (Refereed)
    Abstract [en]

    The range of the recently described seaweed Fucus radicans is limited to the Bothnian Sea and the northern Baltic Sea while the range of the sympatric Fucus vesiculosus extends outside the Baltic Sea. Here we present results from a survey of the distribution and relative abundance of F. radicans and F. vesiculosus and abundance of associated herbivores along the range of F. radicans in Sweden. Both Fucus species were equally common. Herbivores were found in significantly higher numbers on F. radicans. The range of the herbivore Idotea balthica overlaps the southern range of F. radicans and is known to decrease the abundance of fucoids through grazing. We therefore hypothesized that if I. balthica has a preference for F. radicans it could affect the range of F. radicans. To test the preference of I. balthica we performed a bioassay where it had a choice between F. radicans and F. vesiculosus. Another bioassay was performed with the most common herbivore in our survey, Gammarus spp. Both herbivores consumed significantly more F. radicans than F. vesiculosus. Our results indicate that grazing may be an important factor in limiting the southern range of F. radicans along the Swedish coast.

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