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  • 1.
    Abrahamsson, K., Choo, K.-S., Pedersén, M., Johansson, G. and Snoeijs, P.
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Faculty of Science and Technology, Biology, Department of Evolutionary Biology. Department of Ecology and Evolution, Plant Ecology. PLANT ECOLGY.
    Effects of temperature on the production of hydrogen peroxide and volatile halocarbons by brackish-water algae2003In: Phytochemistry, Vol. 64, p. 725-734Article in journal (Refereed)
  • 2.
    Andersson, M., Van Nieuwerburgh, L. and Snoeijs, P.
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Faculty of Science and Technology, Biology, Department of Evolutionary Biology. Department of Ecology and Evolution, Plant Ecology. PLANT ECOLGY.
    Pigment transfer from phytoplankton to zooplankton with emphasis on astaxanthin production in the Baltic Sea food web2003In: Marine Ecology Progress Series, Vol. 254, p. 213-224Article in journal (Refereed)
  • 3.
    Andersson, Markus
    et al.
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Faculty of Science and Technology, Biology, Department of Ecology and Evolution. Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Faculty of Science and Technology, Biology, Department of Ecology and Evolution, Plant Ecology. Växtekologi.
    Schubert, H
    Pedersén, M
    Snoeijs, Pauli
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Faculty of Science and Technology, Biology, Department of Ecology and Evolution. Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Faculty of Science and Technology, Biology, Department of Ecology and Evolution, Plant Ecology. Växtekologi.
    Different patterns of carotenoid composition and photosynthesis acclimation in two tropical red algae2006In: Marine Biology, Vol. 14, p. 653-665Article in journal (Refereed)
  • 4.
    Backéus, Ingvar
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Evolution, Ecological Botany.
    "Aldrig i mina dagar har jag lefvat friskare än nu"2006In: Svensk Botanisk Tidskrift, ISSN 0039-646X, Vol. 100, no 1, p. 59-60Article, book review (Other (popular science, discussion, etc.))
  • 5.
    Backéus, Ingvar
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Evolution, Ecological Botany.
    Kartläggningen av nationallandskapet2004In: Svensk Botanisk Tidskrift, ISSN 0039-646X, Vol. 98, no 3-4, p. 207-212Article in journal (Other (popular science, discussion, etc.))
    Abstract [en]

    The late 19th and early 20th century was a time of intensive geological surveys, carried out in an atmosphere of national romanticism. This period has been described in a recent book by science historian Christer Nordlund, which is here presented and commentd on. Of special interest in Sweden was the issue of posglacial land upheaval and its consequencies for the development of the Baltic Sea. Special emphasis in the book is put on the importance of the geological results for plant geography and archaeology. The two botanists Gunnar Andersson and Rutger Sernander were active in this borderland between botany and geology. As scientists they represented very different mentalities and they soon became enemies. Andersson remained sceptical of the postglacial climate scheme developed by Blytt and Sernander, which he considered founded on too few data. A major scientific schism developed which culminated at the International Geological Congress in Stockholm in 1910. Nordlund is probably right in his view that the interdisciplinary work in the late 19th century relating to historical plant geography and geological development had an impoartant impact on early ecology and its formation as a science.

  • 6.
    Backéus, Ingvar
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Evolution, Ecological Botany.
    Landskapsblommor2005In: Människan och floran, Stockholm: Wahlström & Widstrand , 2005, p. 394-394Chapter in book (Other (popular science, discussion, etc.))
  • 7.
    Backéus, Ingvar
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Evolution, Ecological Botany.
    Swedish students discover cultural and natural wealth of Tanzania2005In: Dryland Biodiversity, Vol. 6, p. 24-25Article in journal (Refereed)
  • 8.
    Backéus, Ingvar
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Evolution, Ecological Botany. Växtekologi.
    The dynamics of Miombo woodlands in a Tanzanian village2005In: Sustainable biodiversity management for reduced community vulnerability to drought.: Proceedings of the 4th RPSUD Workshop held at Lake Bogoria, Kenya October 1st to 3rd, 2003., 2005, p. 105-116Conference paper (Refereed)
  • 9.
    Backéus, Ingvar
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Evolution, Ecological Botany.
    The international M.Sc. training in biodiversity in Uppsala2006In: Proc. 5th RPSUD Workshop, Nakuru, Kenya, 14-17 Nov. 2004, 2006Conference paper (Other academic)
  • 10.
    Backéus, Ingvar
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Evolution, Ecological Botany. Växtekologi.
    The research programme "Man-land interrelations in semi-arid Tanzania"2004In: Management of dryland biodiversity in eastern Africa: Proceedings of regional workshop, National Museum. Kenya, Nairobi, 30 July-1 Aug., 1997, 2004, p. 58-64Conference paper (Refereed)
  • 11.
    Backéus, Ingvar
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Evolution, Ecological Botany.
    Lindberg, Clas
    Uppsala University, Disciplinary Domain of Humanities and Social Sciences, Faculty of Social Sciences, Department of Social and Economic Geography.
    Strömquist, Lennart
    Uppsala University, Disciplinary Domain of Humanities and Social Sciences, Faculty of Social Sciences, Department of Social and Economic Geography.
    Past, present and  future: perspectives in landscape dynamics as seen from two case  studies in Tanzania2009In: Turning Science Into Action: biodiversity Conservation and Natural Resources Management in Africa, Trenton, NJ: Africa World Press, 2009Conference paper (Other academic)
    Abstract [en]

    Landscapes bear witness on past and present natural and societal processes on many different temporal and spatial scales. Major changes of the physical landscape are related to land-forming events, usually followed by continuous processes like weathering, soil formation and erosion. Observed, short-term changes in the physical environment might therefore be adjustments to past events, or the passing of thresholds, rather than reflecting present social and environmental processes.

    The different perspectives will be discussed with examples from two Tanzanian villages. In the first example we show how a combination of geological observations and later spatial information from maps and satellite data, field observations, information from villagers and archive studies has increased the observation period and made it possible to map, analyze and explain the natural and human influences on the distribution pattern of miombo woodland in Tanzania and to relate present landscapes to natural events and human decisions in the past, still making their footprints on the present day environment.

    This village forms a pocket of apparently sustainable landuse amidst a matrix of more or less degraded land. Another such pocket is found in the Mbulu highlands in northern Tanzania, where it has been explained as a result of intensification of agriculture. In our case we see rather a gradual expansion of the area under shifting cultivation in an area where land is not limiting.

    A historical explanation for this development is the fact that this village was little involved in the colonial economy and the villagization program during the 1970s (the “Operation”). Therefore, the population has remained comparatively homogenous and there is continuity in governance. As also population growth has been moderate, its population has been able to continue its traditional landuse in a sustainable way. Today, however, the situation is rapidly changing. Strong economic interests from outside tend to marginalize the influence the villagers have on their own forest resources. External forces are now more important than the internal resource use.

    With the concept “simple reproduction squeeze” Henry Bernstein pointed out declining terms of trade for agricultural products as one driving force of agricultural change, requiring constantly increasing production to maintain the income. In most of Africa there is now a negative spiral of land degradation and poverty, and it seems unlikely that industrialisation or the service sector will grow sufficiently to provide livelihoods for the rising numbers of people who no longer can find a livelihood in the traditional agricultural sector. Hence, rural economies must develop and diversify its use of local resources. Our second example is a village where local initiatives could possibly form a basis for an escape from Bernstein’s squeeze. It is important to study closely how such initiatives could develop within a framework of sustained environment and biodiversity. Although alien words like “sustainability”, “development” and “biodiversity” are unlikely to be well understood in the village, they are nevertheless likely to be discussed locally in people’s attempts to escape from the “squeeze”. Therefore, as scientists we need a better knowledge of people’s motives for acting the way they do and of their perceptions of development and sustainability, i.e. an understanding of the local development discourse.

  • 12.
    Backéus, Ingvar
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Evolution, Ecological Botany.
    Pettersson, Börge
    Strömquist, Lennart
    Uppsala University, Disciplinary Domain of Humanities and Social Sciences, Faculty of Social Sciences, Department of Social and Economic Geography.
    Ruffo, C
    Tree communities and structural dynamics in miombo (Brachystegia-Julbernardia) woodland, Tanzania2006In: Forest Ecology and Management, ISSN 0378-1127, E-ISSN 1872-7042, Vol. 230, no 1-3, p. 171-178Article in journal (Refereed)
    Abstract [en]

    Tree vegetation and size structure was sampled in a miombo woodland area in E Tanzania and related to environmental factors, particularly soil and disturbance history. A total of 86 tree species was found. Four plant communities were distinguished through multivariate classification. Community 1 was dominated by Brachystegia boehmii, Brachystegia bussei and Julbernardia globiflora, and community 2 by B. boehmii and Brachystegia spiciformis. Community 1 was found on grey, eroded soil and community 2 on red, residual soil, a fact that opens up possibilities to use soil signals of satellite data for vegetation mapping. Community 3 is heavily disturbed miombo woodland near villages and community 4 was found on more clayey soil where miombo woodland is not expected. At our 42 sampled sites, density ranged from 74 to 1041 individuals ha−1 and basal area from 3.9 to 16.7 m2 ha−1. Regeneration is generally good but large sized trees are less prominent in communities 3 and 4 due to harvesting. With reduced disturbance miombo species may rapidly resume dominance in community 3. A higher than expected representation by the size class 30–40 (−50) cm dbh in community 2 is probably related to disturbance history. Prevalence of certain species (Pseudolachnostylis maprouneifolia, Pterocarpus angolensis and Diplorhynchos condylocarpon) may be related to frequent fires. Selective logging will soon cause extinction of Dalbergia melanoxylon, whereas Pterocarpus angolensis still has good regeneration, possibly because individuals below logging size have a good seed set. A way to get an easy overview of size classes in all species in an area using PCA is discussed.

  • 13.
    Backéus, Ingvar
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Evolution, Ecological Botany.
    Spada, Francesco
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Evolution, Ecological Botany.
    Introduction2009In: The rural landscapes of Europe: how man has shaped European nature / [ed] Urban Emanuelsson, Formas , 2009, p. 7-8Chapter in book (Other (popular science, discussion, etc.))
  • 14.
    Bakker, J.P.
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Evolution, Ecological Botany.
    Rosén, Eje
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Evolution, Ecological Botany.
    Steg, K.
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Evolution, Ecological Botany.
    Re-establishment of alvar plant species in abandoned arable fields on Öland2007In: Acta Phytogeographica Suecica, ISSN 0084-5914, Vol. 88, p. 73-82Article in journal (Refereed)
    Abstract [en]

    In the past, arable fields were established locally on the alvar on Öland. Several persisted until the present time, but some of them were abandoned shorter or longer ago. We found a series of arable fields forming a chronosequence: still cultivated, ca. 20 years abandoned, ca. 50 years abandoned, and never cultivated. Species of man-influenced habitats gradually disappeared from the former arable fields, but a few persisted after 50 years. A group of alvar species had re-established after 20 years, but others did not re-establish even after 50 years of abandonment, although they are present in the local species pool. We found no evidence of dispersal as a constraint for re-establishment.

  • 15.
    Barros, M. P., Pedersén, M., Colepicolo, P. and Snoeijs, P.
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Faculty of Science and Technology, Biology, Department of Evolutionary Biology. Department of Ecology and Evolution, Plant Ecology. PLANT ECOLGY.
    Self-shading protects phytoplankton communities against H2O2-induced oxidative damage2003In: Aquatic Microbial Ecology, Vol. 30, p. 275-282Article in journal (Refereed)
  • 16. Berendse, F
    et al.
    van Breemen, N
    Rydin, Håkan
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Evolution, Ecological Botany.
    Buttler, A
    Heijmans, M
    Hoosbeek, MR
    Lee, JA
    Mitchell, E
    Saarinen, T
    Vasander, H
    Wallen, B
    Raised atmospheric CO2 levels and increased N deposition cause shifts in plant species composition and production in Sphagnum bogs2001In: Global Change Biology, ISSN 1354-1013, E-ISSN 1365-2486, Vol. 7, no 5, p. 591-598Article in journal (Refereed)
    Abstract [en]

    Part of the missing sink in the global CO2 budget has been attributed to the positive effects of CO2 fertilization and N deposition on carbon sequestration in Northern Hemisphere terrestrial ecosystems. The genus Sphagnum is one of the most important groups of plant species sequestrating carbon in temperate and northern bog ecosystems, because of the low decomposability of the dead material it produces. The effects of raised CO2 and increased atmospheric N deposition on growth of Sphagnum and other plants were studied in bogs at four sites across Western Europe. Contrary to expectations, elevated CO2 did not significantly affect Sphagnum biomass growth. Increased N deposition reduced Sphagnum mass growth, because it increased the cover of vascular plants and the tall moss Polytrichum strictum. Such changes in plant species composition may decrease carbon sequestration in Sphagnum-dominated bog ecosystems.

  • 17.
    Berg, H.
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Faculty of Science and Technology, Biology, Department of Evolutionary Biology. Department of Ecology and Evolution, Plant Ecology. PLANT ECOLGY.
    Factors influencing seed:ovule ratios and reproductive success in four cleistogamous species: a comparison between two flower types2003In: Plant Biology, Vol. 5, p. 194-202Article in journal (Refereed)
  • 18.
    Berg, Henrik
    et al.
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Faculty of Science and Technology, Biology, Department of Ecology and Evolution. Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Faculty of Science and Technology, Biology, Department of Ecology and Evolution, Plant Ecology.
    Becker, U
    Matthies, D
    Phenotypic plasticity in Carlina vulgaris: effects of geographical origin, population size, and population isolation2005In: Oecologia, Vol. 143, p. 220-231Article in journal (Refereed)
  • 19.
    Bergsten, Anna
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Evolution, Ecological Botany.
    Population Differentiation in Solidago virgaurea along Altitudinal Gradients2009Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Altitudinal gradients offer attractive opportunities for studies of population differentiation in response to environmental heterogeneity. In this thesis, I examined population differentiation along altitudinal gradients by combining common-garden experiments with field studies and experiments in alpine, subalpine and boreal populations of the perennial herb Solidago virgaurea. More specifically, I determined whether leaf physiology in terms of nitrogen concentration and resorption, flowering phenology, flower production and reproductive effort vary along altitudinal gradients.

    Nitrogen concentration in green leaves were higher in alpine than in subalpine and boreal populations. These differences persisted when plants were grown from seeds in a common-garden experiment at two sites, suggesting that the differences have a genetic component. There was mixed support for a trade-off between maximized carbon gain through the maintenance of high nitrogen concentration, and minimized nitrogen loss through high resorption.

    In their natural habitats alpine populations began flowering later than subalpine populations, but this difference was reversed when plants were grown in a common environment. This suggests that genetic differences among populations counteract environmental effects and reduce phenotypic variation in flowering time among populations. Flowering time thus shows countergradient genetic variation in S. virgaurea.

    In a common-garden experiment, boreal populations produced more flowers and had a higher reproductive effort than subalpine and alpine populations indicating habitat-specific genetic differences in reproductive allocation. In a field study, which included three populations, seed set was close to zero in the alpine population, intermediate in the subalpine population, and high in the boreal population. Experimental flower removal showed that seed production was associated with a considerable cost in terms of reduced flowering propensity the following year, but did not support the hypothesis that a large floral display is important for pollination success.

  • 20.
    Boberg, Elin
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Evolution, Ecological Botany.
    Evolution of Spur Length in a Moth-pollinated Orchid2010Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    There is considerable evidence that pollinator shifts can explain many differences in flower morphology between closely related plant species, but the extent to which pollinator shifts can explain the maintenance of among-population variation in floral traits within species is poorly known. In this thesis, I combined comparative and experimental approaches to examine the evolution of floral traits in the moth-pollinated orchid Platanthera bifolia. More specifically, I investigated (1) the relationship between flower and pollinator morphology, (2) phenotypic selection on morphology and phenology in populations in contrasting environments, (3) components of prezygotic reproductive isolation among divergent populations, and (4) the adaptive and functional significance of two correlated floral traits.

    A study of Scandinavian of P. bifolia populations revealed that spur length was positively correlated with proboscis length of local pollinators, which suggests that variation in spur length reflects adaptive evolution in response to geographically variable pollinator-mediated selection.

    A phenotypic selection study on Öland, SE Sweden, suggested that disruptive selection on spur length contributes to the maintenance of a bimodal distribution of spur length in mixed habitats, but provided very limited evidence of divergent selection on plant morphology and flowering phenology in grassland and woodland habitats.

    Field experiments revealed strong reproductive isolation between divergent populations on Öland, due to differences in spatial distribution, flowering phenology, and pollinators, and among-population incompatibility. The results suggest that prezygotic reproductive isolation contributes to the maintenance of population differentiation in floral traits in P. bifolia.

    A field manipulation experiment demonstrated that spur length but not perianth size affects pollination success and seed production. This suggests that among-population differentiation in perianth size may be the result of a genetic correlation with spur length.

    Taken together, the results of this thesis suggest that pollinator-mediated selection can shape the evolution of intraspecific floral variation.

    List of papers
    1. Pollinator shifts and the evolution of spur length in the moth-pollinated orchid Platanthera bifolia
    Open this publication in new window or tab >>Pollinator shifts and the evolution of spur length in the moth-pollinated orchid Platanthera bifolia
    Show others...
    2014 (English)In: Annals of Botany, ISSN 0305-7364, E-ISSN 1095-8290, Vol. 113, no 2, p. 267-275Article in journal (Refereed) Published
    Abstract [en]

    Plantpollinator interactions are thought to have shaped much of floral evolution. Yet the relative importance of pollinator shifts and coevolutionary interactions for among-population variation in floral traits in animal-pollinated species is poorly known. This study examined the adaptive significance of spur length in the moth-pollinated orchid Platanthera bifolia. Geographical variation in the length of the floral spur of P. bifolia was documented in relation to variation in the pollinator fauna across Scandinavia, and a reciprocal translocation experiment was conducted in south-east Sweden between a long-spurred woodland population and a short-spurred grassland population. Spur length and pollinator fauna varied among regions and habitats, and spur length was positively correlated with the proboscis length of local pollinators. In the reciprocal translocation experiment, long-spurred woodland plants had higher pollination success than short-spurred grassland plants at the woodland site, while no significant difference was observed at the grassland site. The results are consistent with the hypothesis that optimal floral phenotype varies with the morphology of the local pollinators, and that the evolution of spur length in P. bifolia has been largely driven by pollinator shifts.

    Keywords
    Pollinator shifts, floral traits, spur length, proboscis length, pollination success
    National Category
    Biological Sciences
    Identifiers
    urn:nbn:se:uu:diva-113080 (URN)10.1093/aob/mct217 (DOI)000330193100006 ()
    Available from: 2010-01-25 Created: 2010-01-25 Last updated: 2018-06-05Bibliographically approved
    2. Phenotypic selection on floral traits in divergent populations of the moth-pollinated orchid Platanthera bifolia
    Open this publication in new window or tab >>Phenotypic selection on floral traits in divergent populations of the moth-pollinated orchid Platanthera bifolia
    (English)Manuscript (preprint) (Other academic)
    Abstract [en]

    Among-population differences in flower morphology is commonly attributed to divergent natural selection mediated by pollinators, but comparisons of current selection in populations growing in contrasting environments are scarce. In the moth-pollinated orchid Platanthera bifolia, floral morphology and flowering phenology differ between grassland and woodland populations on the island Öland, SE Sweden. To examine whether among-population variation in floral morphology is consistent with differences in current selection, we documented phenotypic selection through female and male function on flowering phenology, plant height, flower production and spur length in three populations. One grassland and one woodland population were studied in three years, and one population bimodal for spur length and occurring in a mixed habitat was studied in one year. There was evidence of disruptive selection on spur length in the population in the mixed habitat. In one of three years, there was evidence of divergent selection on plant height between the grassland and woodland population.  In all three years selection favoured longer nectar spurs; selection gradients were statistically significant in the short-spurred grassland population, but not in the long-spurred woodland population. In both populations, there was directional selection for earlier flowering and more flowers through female function. Seed production was pollen limited in the grassland population. The results support the hypothesis that disruptive selection through female reproductive success contributes to the maintenance of a bimodal distribution of spur length in P. bifolia in mixed habitats, but provides very limited evidence of divergent selection on plant morphology and flowering phenology in grassland and woodland populations of P. bifolia. The results are discussed in relation to the evolution of floral traits and the challenges associated with detecting stabilizing selection in natural populations.

    Keywords
    Disruptive selection, divergent selection, flower morphology, flowering phenology, selection analysis, seed output, pollen removal
    National Category
    Biological Sciences
    Identifiers
    urn:nbn:se:uu:diva-113083 (URN)
    Available from: 2010-01-25 Created: 2010-01-25 Last updated: 2011-02-09Bibliographically approved
    3. Reproductive isolation among divergent populations of the moth-pollinated orchid Platanthera bifolia
    Open this publication in new window or tab >>Reproductive isolation among divergent populations of the moth-pollinated orchid Platanthera bifolia
    (English)Manuscript (preprint) (Other academic)
    Abstract [en]

    Differentiation in floral traits has been documented between populations in contrasting habitats in several species of flowering plants, but few studies have investigated whether barriers to reproduction contribute to the maintenance of this variation. We investigated components of prezygotic reproductive isolation between short-spurred and long-spurred populations of the moth-pollinated orchid Platanthera bifolia on the island of Öland, SE Sweden. Short-spurred and long-spurred populations were reproductively isolated due to spatial isolation, and differences in flowering time, pollinator morphology and behaviour. The index of reproductive isolation due to pollinators and flowering time was higher for the early-flowering long-spurred plants than it was for the late-flowering short-spurred plants. In addition, we documented a postpollination isolation mechanism manifested as reduced fruit formation in short-spurred plants when pollinated with pollen from long-spurred plants. The results indicate that strong reproductive isolation contribute to the maintenance of population differentiation in morphology and phenology between long-spurred and short-spurred populations of P. bifolia.

    Keywords
    Reproductive isolation, spur length, population differentiation, speciation
    National Category
    Biological Sciences
    Identifiers
    urn:nbn:se:uu:diva-113085 (URN)
    Available from: 2010-01-25 Created: 2010-01-25 Last updated: 2011-02-09Bibliographically approved
    4. Despite their apparent integration, spur length but not perianth size affects reproductive success in the moth-pollinated orchid Platanthera bifolia
    Open this publication in new window or tab >>Despite their apparent integration, spur length but not perianth size affects reproductive success in the moth-pollinated orchid Platanthera bifolia
    2009 (English)In: Functional Ecology, ISSN 0269-8463, E-ISSN 1365-2435, Vol. 23, no 5, p. 1022-1028Article in journal (Refereed) Published
    Abstract [en]

    The evolution of many floral traits is thought to have been shaped  by pollinator-mediated selection for increased attractiveness or an   improved mechanical fit of flowers to pollinators. Yet, few studies have examined experimentally the independent and interactive effects of   different aspects of flower morphology on plant reproductive success.   In the orchid Platanthera bifolia, perianth size and spur length are   positively correlated within and among populations. To test the hypothesis that pollination success and seed output increases with   increasing perianth size and spur length, we manipulated the two traits   in a factorial design in a long-spurred population of P. bifolia   pollinated by long-tongued hawkmoths. Additionally, to determine   whether differences in selfing rate can explain variation in fruit set   and fruit size, we performed controlled self- and cross-pollination.   Plants with long spurs had more flowers pollinated, more pollen removed   and produced more and larger fruits compared to plants with short   spurs. In contrast, perianth size did not affect the pollination   success or fruit production of P. bifolia.   Fruit production and fruit size did not differ among flowers pollinated   with self- and cross pollen, respectively. This indicates that reduced   pollen deposition rather than pollinator-mediated self-pollination   caused the reduction in fruit set and fruit volume observed after   shortening of the spur.   The results demonstrate that spur length, but not perianth size, is   critical for reproductive success in P. bifolia, and suggest that   among-population differentiation in perianth size may reflect a  correlated response to selection on spur length. The results are  consistent with the hypothesis that visual display is less important   than other cues for the reproductive success of P. bifolia, and   underscore the necessity to experimentally examine the functional   significance of putatively adaptive traits.

    Keywords
    pollination success, seed output, floral evolution, floral display, flower morphology, pollen removal
    National Category
    Biological Sciences
    Identifiers
    urn:nbn:se:uu:diva-108552 (URN)10.1111/j.1365-2435.2009.01595.x (DOI)000269976800020 ()
    Available from: 2009-09-22 Created: 2009-09-22 Last updated: 2017-12-13Bibliographically approved
  • 21.
    Boberg, Elin
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Evolution, Ecological Botany.
    Xu, Liu
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Evolution, Ecological Botany.
    Ågren, Jon
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Evolution, Ecological Botany.
    Phenotypic selection on floral traits in divergent populations of the moth-pollinated orchid Platanthera bifoliaManuscript (preprint) (Other academic)
    Abstract [en]

    Among-population differences in flower morphology is commonly attributed to divergent natural selection mediated by pollinators, but comparisons of current selection in populations growing in contrasting environments are scarce. In the moth-pollinated orchid Platanthera bifolia, floral morphology and flowering phenology differ between grassland and woodland populations on the island Öland, SE Sweden. To examine whether among-population variation in floral morphology is consistent with differences in current selection, we documented phenotypic selection through female and male function on flowering phenology, plant height, flower production and spur length in three populations. One grassland and one woodland population were studied in three years, and one population bimodal for spur length and occurring in a mixed habitat was studied in one year. There was evidence of disruptive selection on spur length in the population in the mixed habitat. In one of three years, there was evidence of divergent selection on plant height between the grassland and woodland population.  In all three years selection favoured longer nectar spurs; selection gradients were statistically significant in the short-spurred grassland population, but not in the long-spurred woodland population. In both populations, there was directional selection for earlier flowering and more flowers through female function. Seed production was pollen limited in the grassland population. The results support the hypothesis that disruptive selection through female reproductive success contributes to the maintenance of a bimodal distribution of spur length in P. bifolia in mixed habitats, but provides very limited evidence of divergent selection on plant morphology and flowering phenology in grassland and woodland populations of P. bifolia. The results are discussed in relation to the evolution of floral traits and the challenges associated with detecting stabilizing selection in natural populations.

  • 22.
    Boberg, Elin
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Evolution, Ecological Botany.
    Ågren, Jon
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Evolution, Ecological Botany.
    Despite their apparent integration, spur length but not perianth size affects reproductive success in the moth-pollinated orchid Platanthera bifolia2009In: Functional Ecology, ISSN 0269-8463, E-ISSN 1365-2435, Vol. 23, no 5, p. 1022-1028Article in journal (Refereed)
    Abstract [en]

    The evolution of many floral traits is thought to have been shaped  by pollinator-mediated selection for increased attractiveness or an   improved mechanical fit of flowers to pollinators. Yet, few studies have examined experimentally the independent and interactive effects of   different aspects of flower morphology on plant reproductive success.   In the orchid Platanthera bifolia, perianth size and spur length are   positively correlated within and among populations. To test the hypothesis that pollination success and seed output increases with   increasing perianth size and spur length, we manipulated the two traits   in a factorial design in a long-spurred population of P. bifolia   pollinated by long-tongued hawkmoths. Additionally, to determine   whether differences in selfing rate can explain variation in fruit set   and fruit size, we performed controlled self- and cross-pollination.   Plants with long spurs had more flowers pollinated, more pollen removed   and produced more and larger fruits compared to plants with short   spurs. In contrast, perianth size did not affect the pollination   success or fruit production of P. bifolia.   Fruit production and fruit size did not differ among flowers pollinated   with self- and cross pollen, respectively. This indicates that reduced   pollen deposition rather than pollinator-mediated self-pollination   caused the reduction in fruit set and fruit volume observed after   shortening of the spur.   The results demonstrate that spur length, but not perianth size, is   critical for reproductive success in P. bifolia, and suggest that   among-population differentiation in perianth size may reflect a  correlated response to selection on spur length. The results are  consistent with the hypothesis that visual display is less important   than other cues for the reproductive success of P. bifolia, and   underscore the necessity to experimentally examine the functional   significance of putatively adaptive traits.

  • 23.
    Boberg, Elin
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Evolution, Ecological Botany.
    Ågren, Jon
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Evolution, Ecological Botany.
    Reproductive isolation among divergent populations of the moth-pollinated orchid Platanthera bifoliaManuscript (preprint) (Other academic)
    Abstract [en]

    Differentiation in floral traits has been documented between populations in contrasting habitats in several species of flowering plants, but few studies have investigated whether barriers to reproduction contribute to the maintenance of this variation. We investigated components of prezygotic reproductive isolation between short-spurred and long-spurred populations of the moth-pollinated orchid Platanthera bifolia on the island of Öland, SE Sweden. Short-spurred and long-spurred populations were reproductively isolated due to spatial isolation, and differences in flowering time, pollinator morphology and behaviour. The index of reproductive isolation due to pollinators and flowering time was higher for the early-flowering long-spurred plants than it was for the late-flowering short-spurred plants. In addition, we documented a postpollination isolation mechanism manifested as reduced fruit formation in short-spurred plants when pollinated with pollen from long-spurred plants. The results indicate that strong reproductive isolation contribute to the maintenance of population differentiation in morphology and phenology between long-spurred and short-spurred populations of P. bifolia.

  • 24.
    Bolmgren, Kjell
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Evolution, Ecological Botany.
    Cowan, Peter D.
    Time – size tradeoffs: a phylogenetic comparative study of flowering time, plant height and seed mass in a north-temperate flora2008In: Oikos, ISSN 0030-1299, E-ISSN 1600-0706, Vol. 117, no 3, p. 424-429Article in journal (Refereed)
    Abstract [en]

    Parents face a timing problem as to when they should begin devoting resources from their own growth and survival to mating and offspring development. Seed mass and number, as well as maternal survival via plant size, are dependent on time for development. The time available in the favorable season will also affect the size of the developing juveniles and their survival through the unfavorable season. Flowering time may thus represent the outcome of such a time partitioning problem. We analyzed correlations between flowering onset time, seed mass, and plant height in a north-temperate flora, using both cross-species comparisons and phylogenetic comparative methods. Among perennial herbs, flowering onset time was negatively correlated with seed mass (i.e. plants with larger seeds started flowering earlier) while flowering onset time was positively correlated with plant height. Neither of these correlations was found among woody plants. Among annual plants, flowering onset time was positively correlated with seed mass. Cross-species and phylogenetically informed analyses largely agreed, except that flowering onset time was also positively correlated with plant height among annuals in the cross-species analysis. The different signs of the correlations between flowering onset time and seed mass (compar. gee regression coefficient=−7.8) and flowering onset time and plant height (compar. gee regression coefficient=+30.5) for perennial herbs, indicate that the duration of the growth season may underlie a tradeoff between maternal size and offspring size in perennial herbs, and we discuss how the partitioning of the season between parents and offspring may explain the association between early flowering and larger seed mass among these plants.

  • 25. Boresjö Bronge, L
    et al.
    Flodin, L.Å.
    Gunnarsson, Urban
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Faculty of Science and Technology, Biology, Department of Ecology and Evolution. Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Faculty of Science and Technology, Biology, Department of Ecology and Evolution, Plant Ecology. Växtekologi.
    Mycket högupplösande satellitdata för upptäckt av långsiktiga vegetationsförändringar på öppna mossar. Statusrapport 20062007Report (Other (popular scientific, debate etc.))
  • 26. Bragazza, L
    et al.
    Limpens, J
    Gerdol, R
    Grosvernier, P
    Hájek, M
    Hájek, T
    Hajkova, P
    Hansen, I
    Iacumin, P
    Kutnar, L
    Rydin, Håkan
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Faculty of Science and Technology, Biology, Department of Ecology and Evolution. Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Faculty of Science and Technology, Biology, Department of Ecology and Evolution, Plant Ecology.
    Tahvanainen, T
    Nitrogen concentration and delta(15)N signature of ombrotrophic Sphagnum mosses at different N deposition in Europe2005In: Global Change Biology, Vol. 11, p. 106-114Article in journal (Refereed)
  • 27. Bragazza, L
    et al.
    Rydin, Håkan
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Faculty of Science and Technology, Biology, Department of Ecology and Evolution. Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Faculty of Science and Technology, Biology, Department of Ecology and Evolution, Plant Ecology.
    Gerdol, R
    Multiple gradients in mire vegetation: a comparison of a Swedish and an Italian bog2005In: Plant Ecology, Vol. 177, p. 223-236Article in journal (Refereed)
  • 28. Bragazza, L
    et al.
    Tahvanainen, T
    Kutnar, L
    Rydin, Håkan
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Faculty of Science and Technology, Biology, Department of Evolutionary Biology. Department of Ecology and Evolution, Plant Ecology. Växtekologi.
    Limpens, J
    Nutritional constraints in ombrotrophic Sphagnum plants under increasing atmospheric nitrogen deposition in Europe2004In: New Phytologist, Vol. 163, p. 609-616Article in journal (Refereed)
  • 29. Bragazza, Luca
    et al.
    Freeman, Chris
    Jones, Timothy
    Rydin, Håkan
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Evolution, Ecological Botany.
    Limpens, Juul
    Fenner, Nathalie
    Ellis, Tim
    Gerdol, Renato
    Hajek, Michal
    Hajek, Tomas
    Lacumin, Paola
    Kutnar, Lado
    Tahvanainen, Teemu
    Toberman, Hannah
    Atmospheric nitrogen deposition promotes carbon loss from peat bogs2006In: Proceedings of the National Academy of Sciences of the United States of America, ISSN 0027-8424, E-ISSN 1091-6490, Vol. 103, no 51, p. 19386-19389Article in journal (Refereed)
    Abstract [en]

    Peat bogs have historically represented exceptional carbon (C) sinks because of their extremely low decomposition rates and consequent accumulation of plant remnants as peat. Among the factors favoring that peat accumulation, a major role is played by the chemical quality of plant litter itself, which is poor in nutrients and characterized by polyphenols with a strong inhibitory effect on microbial breakdown. Because bogs receive their nutrient supply solely from atmospheric deposition, the global increase of atmospheric nitrogen (N) inputs as a consequence of human activities could potentially alter the litter chemistry with important, but still unknown, effects on their C balance. Here we present data showing the decomposition rates of recently formed litter peat samples collected in nine European countries under a natural gradient of atmospheric N deposition from approximate to 0.2 to 2 g center dot m(-2)center dot yr(-1). We found that enhanced decomposition rates for material accumulated under higher atmospheric N supplies resulted in higher carbon dioxide (CO2) emissions and dissolved organic carbon release. The increased IN availability favored microbial decomposition (i) by removing N constraints on microbial metabolism and (ii) through a chemical amelioration of litter peat quality with a positive feedback on microbial enzymatic activity. Although some uncertainty remains about whether decay-resistant Sphagnum will continue to dominate litter peat, our data indicate that, even without such changes, increased N deposition poses a serious risk to our valuable peatland C sinks.

  • 30. Brooker, Rob W.
    et al.
    Carlsson, Bengt Å.
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Evolution, Ecological Botany.
    Callaghan, Terry V.
    Carex bigelowii Torrey ex Schweinitz (C. rigida Good., non Schrank; C. hyperborea Drejer)2001In: Journal of Ecology, ISSN 0022-0477, E-ISSN 1365-2745, Vol. 89, no 6, p. 1072-1095Article in journal (Refereed)
  • 31. Bu, Z
    et al.
    Yang, Y
    Rydin, Håkan
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Faculty of Science and Technology, Biology, Department of Ecology and Evolution. Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Faculty of Science and Technology, Biology, Department of Ecology and Evolution, Plant Ecology.
    Lang, H
    Age structures of modules of clonal peatland sedge Carex middendorffii2005In: Chinese Geographical Science, Vol. 15, p. 269-274Article in journal (Refereed)
  • 32.
    Busse, S. and Snoeijs, P.
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Faculty of Science and Technology, Biology, Department of Evolutionary Biology. Department of Ecology and Evolution, Plant Ecology. PLANT ECOLGY.
    Gradient responses of diatom communities in the Bothnian Sea (northern Baltic Sea), with emphasis on responses to water movement2003In: Phycologia, Vol. 42, p. 451-464Article in journal (Refereed)
  • 33.
    Carlsson, Bengt Å.
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Evolution, Ecological Botany.
    Karlsson, P. Staffan
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Evolution, Ecological Botany.
    Svensson, Brita M.
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Evolution, Ecological Botany.
    Alpine and subalpine vegetation1999In: Swedish plant geography / [ed] Rydin, Snoeijs & Diekmann, Uppsala: Svenska växtgeografiska sällskapet , 1999, p. 75-89Chapter in book (Refereed)
  • 34. Casella, L
    et al.
    Spada, Francesco
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Evolution, Ecological Botany.
    The Floating Island of Posta Fibreno: an example of relic mires in Central Italy2009In: Annali di botanica, ISSN 0365-0812, Vol. 9Article in journal (Refereed)
  • 35. Choo, K
    et al.
    Snoeijs, Pauli
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Faculty of Science and Technology, Biology, Department of Evolutionary Biology. Department of Ecology and Evolution, Plant Ecology.
    Pedersén, M
    Oxidative stress tolerance in the filamentous green algae Cladophora glomerata and Enteromorpha ahlneriana2004In: Journal of Experimental Marine Biology and Ecology, Vol. 298, p. 111-123Article in journal (Refereed)
  • 36. Choo, KS
    et al.
    Nilsson, J
    Pedersén, M
    Snoeijs, Pauli
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Faculty of Science and Technology, Biology, Department of Ecology and Evolution. Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Faculty of Science and Technology, Biology, Department of Ecology and Evolution, Plant Ecology.
    Photosynthesis, carbon uptake and antioxidant defence in two coexisting filamentous green algae under different stress conditions2005In: Marin Ecology Progress Series, Vol. 292, p. 127-138Article in journal (Refereed)
  • 37. Cronberg, Nils
    et al.
    Rydin, Håkan
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Faculty of Science and Technology, Biology, Department of Ecology and Evolution. Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Faculty of Science and Technology, Biology, Department of Ecology and Evolution, Plant Ecology. Växtekologi.
    Sphagnum borde heta torvmossa på svenska2006In: Svensk Botanisk Tidskrift, Vol. 100, p. 299-300Article in journal (Other (popular scientific, debate etc.))
  • 38. Cronberg, Nils
    et al.
    Rydin, Håkan
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Faculty of Science and Technology, Biology, Department of Ecology and Evolution. Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Faculty of Science and Technology, Biology, Department of Ecology and Evolution, Plant Ecology.
    Torvmossa - ett nygammalt svenskt namn för Sphagnum2005In: Svensk Botanisk Tidskrift, Vol. 99, p. 290-294Article in journal (Refereed)
  • 39. Dalin, Peter
    et al.
    Ågren, Jon
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Evolution, Ecological Botany.
    Björkman, Christer
    Huttunen, Piritta
    Kärkkäinen, Katri
    Leaf trichome formation and plant resistance to herbivory2008In: Induced plant resistance to herbivory, Springer , 2008, p. 89-105Chapter in book (Other academic)
  • 40.
    de Kroon, Hans
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Evolution, Ecological Botany.
    van Groenendael, Jan M.
    Ehrlén, Johan
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Evolution, Ecological Botany.
    Elasticities: a review of methods and model limitations2000In: Ecology, ISSN 0012-9658, E-ISSN 1939-9170, Vol. 81, no 3, p. 607-618Article in journal (Refereed)
    Abstract [en]

    Elasticity is a perturbation measure in matrix projection models that quantifiesthe proportional change in population growth rate as a function of a proportionalchange in a demographic transition (growth, survival, reproduction, etc.). Elasticities thusindicate the relative "importance" of life cycle transitions for population growth and maintenance.In this paper, we discuss the applications of elasticity analysis, and its extension,loop analysis, in life history studies and conservation. Elasticity can be interpreted as therelative contribution of a demographic parameter to population growth rate. Loop analysisreveals the underlying pathway structure of the life cycle graph. The different kinds ofresults of the two analyses in studies of life histories are emphasized. Because elasticitiesquantify the relative importance of life cycle transitions to population growth rate, it isgenerally inferred that management should focus on the transitions with the largest elasticities.Such predictions based on elasticities seem robust, but we do identify three situationswhere problems may arise. The mathematical properties and biological constraints thatunderlie these pitfalls are explained. Examples illustrate the additional information thatneeds to be taken into account for a sensible use of elasticities in population management.We conclude by indicating topics that are in need of research.

  • 41. Dengler, J
    et al.
    Löbel, Swantje
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Faculty of Science and Technology, Biology, Department of Ecology and Evolution. Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Faculty of Science and Technology, Biology, Department of Ecology and Evolution, Plant Ecology. Växtekologi.
    Dry grassland communities of shallow, skeletal soils (Sedo-Scleranthenea) in northern Europe2006In: Tuexenia, Vol. 26, p. 159-190Article in journal (Refereed)
  • 42. Dengler, J
    et al.
    Löbel, Swantje
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Faculty of Science and Technology, Biology, Department of Ecology and Evolution. Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Faculty of Science and Technology, Biology, Department of Ecology and Evolution, Plant Ecology. Växtekologi.
    The basiphilous dry grasslands of shallow, skeletal soils (Alysso-Sedetalia) on the island of Öland (Sweden), in the context of North and Central Europe2006In: Phytocoenologia, Vol. 36, p. 343-391Article in journal (Refereed)
  • 43. Dengler, Jürgen
    et al.
    Löbel, Swantje
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Evolution, Ecological Botany.
    Dolnik, Christian
    Species constancy depends on plot size - a problem for vegetation classification and how it can be solved2009In: Journal of Vegetation Science, ISSN 1100-9233, E-ISSN 1654-1103, Vol. 20, no 4, p. 754-766Article in journal (Refereed)
    Abstract [en]

    Question   While it is well known that species richness depends on plot size, it  is not generally recognised that the same must be true for constancy. Accordingly, many authors use varying plot sizes when classifying   vegetation based on the comparison of constancies between groups of plots. We ask whether the constancy-area relationship follows a general   rule, how strong the effect of plot sizes is on constancies, and if it  is possible to correct constancies for area. Location For empirical evaluation, we use data from plant communities in the   Czech Republic, Sweden and Russia.   Methods   To assess the potential influence of differences in plot size on   constancies, we develop a mathematical model. Then, we use series of   nested plot species richness data from a wide range of community types   (herbaceous and forest) to determine the parameters of the derived   function and to test how much the shape of the constancy-area   relationship depends on taxa or vegetation types.   Results   Generally, the constancy-area relationship can be described by C   (A)=1-(1-C-0)((A/A0)boolean AND d), with C being constancy, A area, C-0   known constancy on a specific area A(0), and d a damping parameter   accounting for spatial autocorrelation. As predicted by this function,   constancies in plant communities always varied from values near 0% to   near 100% if plot sizes were changed sufficiently. For the studied   vegetation types, a two- to fourfold increase in plot size resulted in   a change of conventional constancy classes, i.e. an increase of   constancy by 20% or more.   Conclusions   Vegetation classification, which largely relies on constancy values,   irrespective of whether traditional or modern fidelity definitions are   used, is strongly prone to distorting scale effects when releves of   different plot sizes are combined in studies. The constancy-area   functions presented allow an approximate transformation of constancies   to other plot sizes but are flawed by idiosyncrasies in taxa and   vegetation types. Thus, we conclude that the best solution for future   surveys is to apply uniform plot sizes within a few a priori delimited   formations and to determine diagnostic species only within these   formations. Finally, we suggest that more detailed analyses of constancy-area relationships can contribute to a better understanding of species-area relationships because the latter are the summation of the first for all species.

  • 44. Ehlers, B. K.
    et al.
    Olesen, J. M.
    Ågren, Jon
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Evolution, Ecological Botany.
    Floral morphology and reproductive success in the orchid Epipactis helleborine: regional and local across-habitat variation2002In: Plant Systematics and Evolution, ISSN 0378-2697, E-ISSN 1615-6110, Vol. 236, no 1-2, p. 19-32Article in journal (Refereed)
    Abstract [en]

    The terrestrial orchid Epipactis helleborine is a morphologically variable species with a wide distribution in Europe. It is pollinated by social wasps, and most populations show the morphological characteristics of outcrossing species. However, local predominantly selfing subspecies and varieties have been documented from drier habitats. To document geographic variation in floral morphology, ability to produce seeds through autogamy, and reproductive success in E. helleborine, we sampled 13 populations from three geographic regions along a latitudinal gradient of c. 1000 km from northern to southern Sweden. In the southernmost region, populations in dry and mesic habitats were compared. Supplemental hand-pollination was conducted to determine whether among-population variation in fruit set could be explained by differences in the natural level of pollination, and whether any relationship between floral morphology and fruit production could be explained by interactions with pollinators. Bagging experiments showed no evidence of autogamy in any of the study populations. Number of flowers, pollinia removal and fruit set varied significantly among populations but did not differ among regions. Pollinia removal was positively correlated with population size and both pollinia removal and fruit set were lower in dry than in mesic habitats. At the level of the individual plant, the number of pollinia removed increased more rapidly with flower number than did number of fruits produced. The hand-pollination experiment indicated that the positive relationship between number of flowers and fruit production was due to a higher degree of pollen limitation in plants with few flowers than in plants with many flowers. The experiment also showed that variation in the level of pollen limitation could only partly explain variation in fruit set among populations.

  • 45.
    Ehrlén, Johan
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Evolution, Ecological Botany.
    The dynamics of plant populations: does the history of individuals matter?2000In: Ecology, ISSN 0012-9658, E-ISSN 1939-9170, Vol. 81, no 6, p. 1675-1684Article in journal (Refereed)
    Abstract [en]

    Historical events have been used to explain a wide range of phenomenaincluding geographical distributions of species, community diversity, and population structure.At the level of individuals, historical effects in which past conditions influence futureperformance are particularly likely to occur in long-lived organisms that store resourcesbetween seasons and that form organs months or years before their elaboration. Such carryovermechanisms have been documented in several perennial plant species, but the implicationsfor population processes are poorly known. In this study, I examine how the historyof individuals influences their future performance, population dynamics, and life cycle,structure in the long-lived herb Lathyrus vernus. Overall effects of plant history on populationdynamics, in terms of growth rate, reproductive values, stable stage distribution,and elasticities, are examined by comparing an ordinary first-order matrix model with asecond-order matrix model. In the latter, not only the present state of individuals, but alsotheir past state is allowed to influence future fate.The results demonstrate that the history of individuals is sometimes important in modelsof population dynamics. Plant size change over a one-year period was negatively correlatedamong time intervals. Addition of the previous year's stage in population models shiftedthe growth rate from positive (X = 1.010) to negative (X = 0.986) and increased theproportion of small established individuals in the stable stage distribution. If historicaleffects are due to a capacity to buffer environmental variation and regain size or state, asin L. vernus, then recruitment contributes less and stasis more to population growth thansuggested by ahistorical models. The presence of historical effects at the level of individuals,in any form, may have important consequences for population development and should beincluded in any interpretation of the life-cycle structure.

  • 46.
    Ehrlén, Johan
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Evolution, Ecological Botany.
    Eriksson, O
    Dispersal limitation and patch occupancy in forest herbs2000In: Ecology, ISSN 0012-9658, E-ISSN 1939-9170, Vol. 81, p. 1667-1674Article in journal (Refereed)
    Abstract [en]

    The distribution of species depends on the availability of suitable habitats, the capacity to disperse to these habitats, and the capacity of populations to persist after establishment. Dispersal limitation implies that not all suitable habitat patches will be occupied by a species. However, the extent to which dispersal limits local distribution is poorly known. In this study, we transplanted seeds, bulbils, and juvenile plants to examine patterns of dispersal limitation and patch occupancy in seven temperate-forest herbs. Recruitment was recorded during four years in 48 patches. The investigated species varied considerably in their natural abundance in the patches. Patterns of seedling emergence and establishment among patches were not related to any of nine investigated abiotic factors. In contrast, the availability of seeds or bulbils was found to limit recruitment in six of the investigated species. Establishment was also successful in many patches where the species did not occur naturally. Estimated patch occupancy in the investigated species ranged from 17.2% to 94.6%. Seed size was positively correlated with the probability of successful establishment of seeds and negatively correlated with patch occupancy. The results suggest that dispersal limitation is an important structuring factor in temperate-forest herb communities. The distribution of species can be perceived as the result of processes operating both among and within patches. Seed size is a key trait in these processes.

  • 47.
    Ehrlén, Johan
    et al.
    Dept of Botany, Stockholm Univ..
    Käck, Sofia
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Evolution, Ecological Botany.
    Ågren, Jon
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Evolution, Ecological Botany.
    Pollen limitation, seed predation and scape length in Primula farinosa2002In: Oikos, ISSN 0030-1299, E-ISSN 1600-0706, Vol. 97, no 1, p. 45-51Article in journal (Refereed)
    Abstract [en]

    Floral display and reward production may affect the attractiveness of a plant to a range of interacting animals including pollinators, herbivores, and vectors of pathogenic fungi. The optimal floral phenotype should therefore depend on the relative importance of selection exerted by both mutualistic and antagonistic animals. The perennial, rosette herb Primula farinosa is polymorphic for scape length. Natural populations may include both plants with flowers displayed well above the ground (the long-scaped morph) and those with flowers positioned very close to the ground (the short-scaped morph). In this study, we conducted a field experiment to examine how the relative fitness of the two scape morphs is affected by interactions with pollinators and fruit predators in two different microhabitats (high and low vegetation). As predicted based on the difference in floral display, supplemental hand-pollination showed that fruit initiation was more strongly pollen-limited in the short-scaped than in the long-scaped morph, and that this difference was significantly larger in high than in low vegetation. Moreover, plants with a short scape experienced lower levels of fruit predation than plants with a long scape. Among open-pollinated controls, there was no significant difference in seed output between the two scape morphs. However, among plants receiving supplemental hand-pollination, short-scaped plants produced significantly more seeds than long-scaped plants. The results suggest that the positive and negative effects of a prominent floral display (increased pollination and seed predation, respectively) balance in the study population, but also that the short-scaped morph would have an advantage at higher pollination intensities. Spatial and temporal variation in pollinator activity and seed predation should result in associated variation in the relative fecundity of the two scape morphs.

  • 48. Ehrlén, Johan
    et al.
    Svensson, Brita M.Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Evolution, Ecological Botany.
    Plant interactions, dispersal and community structure.2000Conference proceedings (editor) (Refereed)
  • 49.
    Emanuelsson, Urban
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Swedish Biodiversity Centre.
    Backéus, Ingvar
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Evolution, Ecological Botany.
    Brukade våtmarker2009In: Europeiska kulturlandskap / [ed] Emanuelsson, Urban, Formas , 2009, p. 274-287Chapter in book (Other (popular science, discussion, etc.))
  • 50.
    Emanuelsson, Urban
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Swedish Biodiversity Centre.
    Backéus, Ingvar
    Uppsala University, Disciplinary Domain of Science and Technology, Biology, Department of Ecology and Evolution, Ecological Botany. Uppsala University, Disciplinary Domain of Science and Technology, Biology, Swedish Biodiversity Centre.
    Farmed wetlands2009In: The rural landscapes of Europe: how man has shaped European nature / [ed] Urban Emanuelsson, Stockholm: Formas , 2009, p. 277-289Chapter in book (Other (popular science, discussion, etc.))
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