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  • 1.
    Banks, H. T.
    et al.
    Center for Research in Scientific Computation North Carolina State University Raleigh, NC, USA.
    Banks, J. E.
    Undergraduate Research Opportunities Center (UROC) California State University, Monterey Bay Seaside, CA, USA.
    Bommarco, Riccardo
    Department of Ecology Swedish University of Agricultural Sciences Uppsala, Sweden.
    Curtsdotter, Alva
    Department of Ecology Swedish University of Agricultural Sciences Uppsala, Sweden.
    Jonsson, Tomas
    University of Skövde, School of Bioscience. University of Skövde, The Systems Biology Research Centre. Department of Ecology Swedish University of Agricultural Sciences Uppsala, Sweden.
    Laubmeier, A. N.
    Center for Research in Scientific Computation North Carolina State University Raleigh, NC, USA.
    Parameter estimation for an allometric food web model2017In: International journal of pure and applied mathematics, ISSN 1311-8080, E-ISSN 1314-3395, Vol. 114, no 1, p. 143-160Article in journal (Refereed)
    Abstract [en]

    The application of mechanistic models to natural systems is of interest to ecological researchers. We use the mechanistic Allometric Trophic Network (ATN) model, whichis well-studied for controlled and theoretical systems, to describe the dynamics of the aphidRhopalosiphum padi in an agricultural field. We diagnose problems that arise in a first attemptat a least squares parameter estimation on this system, including formulation of the modelfor the inverse problem and information content present in the data. We seek to establishwhether the field data, as it is currently collected, can support parameter estimation for theATN model.

  • 2.
    Berg, Sofia
    et al.
    University of Skövde, School of Life Sciences. University of Skövde, The Systems Biology Research Centre. IFM Theory and Modelling, Div. of Theoretical Biology, Linköping Univ., Linköping, Sweden.
    Christianou, Maria
    IFM Theory and Modelling, Div. of Theoretical Biology, Linköping Univ., Linköping, Sweden.
    Jonsson, Tomas
    University of Skövde, School of Life Sciences. University of Skövde, The Systems Biology Research Centre.
    Ebenman, Bo
    IFM Theory and Modelling, Div. of Theoretical Biology, Linköping Univ., Linköping, Sweden.
    Using sensitivity analysis to identify keystone species and keystone links in size-based food webs2011In: Oikos, ISSN 0030-1299, E-ISSN 1600-0706, Vol. 120, no 4, p. 510-519Article in journal (Refereed)
    Abstract [en]

    Human-induced alterations in the birth and mortality rates of species and in the strength of interactions within and between species can lead to changes in the structure and resilience of ecological communities. Recent research points to the importance of considering the distribution of body sizes of species when exploring the response of communities to such perturbations. Here, we present a new size-based approach for assessing the sensitivity and elasticity of community structure (species equilibrium abundances) and resilience (rate of return to equilibrium) to changes in the intrinsic growth rate of species and in the strengths of species interactions. We apply this approach on two natural systems, the pelagic communities of the Baltic Sea and Lake Vättern, to illustrate how it can be used to identify potential keystone species and keystone links. We find that the keystone status of a species is closely linked to its body size. The analysis also suggests that communities are structurally and dynamically more sensitive to changes in the effects of prey on their consumers than in the effects of consumers on their prey. Moreover, we discuss how community sensitivity analysis can be used to study and compare the fragility of communities with different body size distributions by measuring the mean sensitivity or elasticity over all species or all interaction links in a community. We believe that the community sensitivity analysis developed here holds some promise for identifying species and links that are critical for the structural and dynamic robustness of ecological communities.

  • 3.
    Berg, Sofia
    et al.
    University of Skövde, School of Bioscience. University of Skövde, The Systems Biology Research Centre. Dept of Physics, Chemistry and Biology, Div. of Theoretical Biology, Linköping Univ., Linköping, Sweden.
    Pimenov, Aexander
    Weierstrass Inst., Berlin, Germany / Environmental Research Inst., Univ. College Cork, Cork, Ireland.
    Palmer, Catherine
    Weierstrass Inst., Berlin, Germany.
    Emmerson, Mark
    School of Biological Sciences, Queen's Univ. Belfast, Belfast, United Kingdom.
    Jonsson, Tomas
    University of Skövde, School of Bioscience. University of Skövde, The Systems Biology Research Centre. Dept of Ecology, Swedish Univ. of Agricultural Sciences, Uppsala, Sweden.
    Ecological communities are vulnerable to realistic extinction sequences2015In: Oikos, ISSN 0030-1299, E-ISSN 1600-0706, Vol. 124, no 4, p. 486-496Article in journal (Refereed)
  • 4.
    Borrvall, Charlotta
    et al.
    Linköping University.
    Ebenman, Bo
    Linköping University.
    Jonsson, Tomas
    Linköping University.
    Biodiversity lessens the risk of cascading extinction in model food webs2000In: Ecology Letters, ISSN 1461-023X, E-ISSN 1461-0248, Vol. 3, p. 131-136Article in journal (Refereed)
  • 5.
    Brose, Ulrich
    et al.
    Department of Biology, Technical University of Darmstadt, Darmstadt, Germany.
    Cushing, Lara
    Berlow, Eric L.
    Jonsson, Tomas
    University of Skövde, School of Life Sciences.
    Banasek-Richter, Carolin
    Bersier, Louis-Felix
    Blanchard, Julia L.
    Brey, Thomas
    Carpenter, Stephen R.
    Blandenier, Marie-France
    Cohen, Joel E.
    Dawah, Hassan Ali
    Dell, Tony
    Edwards, Francois
    Harper-Smith, Sarah
    Jacob, Ute
    Knapp, Roland A.
    Ledger, Mark E.
    Memmott, Jane
    Mintenbeck, Katja
    Pinnegar, John K.
    Rall, Björn C.
    Rayner, Tom
    Ruess, Liliane
    Ulrich, Werner
    Warren, Philip
    Williams, Rich J.
    Woodward, Guy
    Yodzis, Peter
    Martinez, Neo D.
    Body sizes of consumers and their resources2005In: Ecology, ISSN 0012-9658, E-ISSN 1939-9170, Vol. 86, no 9, p. 2545-2545Article in journal (Refereed)
    Abstract [en]

    Trophic information—who eats whom—and species’ body sizes are two of the most basic descriptions necessary to understand community structure as well as ecological and evolutionary dynamics. Consumer–resource body size ratios between predators and their prey, and parasitoids and their hosts, have recently gained increasing attention due to their important implications for species’ interaction strengths and dynamical population stability. This data set documents body sizes of consumers and their resources. We gathered body size data for the food webs of Skipwith Pond, a parasitoid community of grass-feeding chalcid wasps in British grasslands; the pelagic community of the Benguela system, a source web based on broom in the United Kingdom; Broadstone Stream, UK; the Grand Caric¸aie marsh at Lake Neuchaˆtel, Switzerland; Tuesday Lake, USA; alpine lakes in the Sierra Nevada of California; Mill Stream, UK; and the eastern Weddell Sea Shelf, Antarctica. Further consumer–resource body size data are included for planktonic predators, predatory nematodes, parasitoids, marine fish predators, freshwater invertebrates, Australian terrestrial consumers, and aphid parasitoids. Containing 16 807 records, this is the largest data set ever compiled for body sizes of consumers and their resources. In addition to body sizes, the data set includes information on consumer and resource taxonomy, the geographic location of the study, the habitat studied, the type of the feeding interaction (e.g., predacious, parasitic) and the metabolic categories of the species (e.g., invertebrate, ectotherm vertebrate). The present data set was gathered with the intent to stimulate research on effects of consumer–resource body size patterns on food-web structure, interaction-strength distributions, population dynamics, and community stability. The use of a common data set may facilitate cross-study comparisons and understanding of the relationships between different scientific approaches and models.

  • 6.
    Brose, Ulrich
    et al.
    Department of Biology, Darmstadt University of Technology, Darmstadt, Germany / Pacific Ecoinformatics and Computational Ecology Lab., Berkeley, CA 94703, United States.
    Jonsson, Tomas
    University of Skövde, School of Life Sciences.
    Berlow, Eric L.
    Department of Biology, Darmstadt University of Technology, Darmstadt, Germany / Pacific Ecoinformatics and Computational Ecology Lab., Berkeley, CA 94703, United States / University of California, Merced, Sierra Nevada Research Institute, Yosemite National Park, CA 95389, United States.
    Warren, Philip
    Department of Animal and Plant Sciences, University of Sheffield, Sheffield, United Kingdom.
    Banasek-Richter, Carolin
    Department of Biology, Darmstadt University of Technology, Darmstadt, Germany.
    Bersier, Louis-Felix
    Department of Biology, Unit of Ecology and Evolution, Fribourg, Switzerland.
    Blanchard, Julia L.
    Centre for Environment, Fisheries and Aquaculture Science (CEFAS), Suffolk, United Kingdom.
    Brey, Thomas
    Alfred Wegener Institute for Polar and Marine Research, Bremerhaven, Germany.
    Carpenter, Stephen R.
    Center for Limnology, University of Wisconsin, Madison, WI 53706, United States.
    et al.,
    Consumer-resource body-size relationships in natural food webs2006In: Ecology, ISSN 0012-9658, E-ISSN 1939-9170, Vol. 87, no 10, p. 2411-2417Article in journal (Refereed)
    Abstract [en]

    It has been suggested that differences in body size between consumer and resource species may have important implications for interaction strengths, population dynamics, and eventually food web structure, function, and evolution. Still, the general distribution of consumer-'resource body-size ratios in real ecosystems, and whether they vary systematically among habitats or broad taxonomic groups, is poorly understood. Using a unique global database on consumer and resource body sizes, we show that the mean body-size ratios of aquatic herbivorous and detritivorous consumers are several orders of magnitude larger than those of carnivorous predators. Carnivorous predator-prey body-size ratios vary across different habitats and predator and prey types (invertebrates, ectotherm, and endotherm vertebrates). Predator-prey body-size ratios are on average significantly higher (1) in freshwater habitats than in marine or terrestrial habitats, (2) for vertebrate than for invertebrate predators, and (3) for invertebrate than for ectotherm vertebrate prey. If recent studies that relate body-size ratios to interaction strengths are general, our results suggest that mean consumer-resource interaction strengths may vary systematically across different habitat categories and consumer types.

  • 7.
    Cohen, Joel E.
    et al.
    Laboratory of Populations, Rockefeller Univ. and Columbia Univ., Box 20, 1230 York Avenue, New York, NY 10021, United States.
    Jonsson, Tomas
    University of Skövde, School of Life Sciences.
    Müller, Christine B.
    Centre for Population Biology, Department of Biology, Imperial College at Silwood Park, Ascot, Berks SL5 7PY, United Kingdom / Institute of Environmental Sciences, University of Zürich, Winterthurerstrasse 190, CH-8057 Zürich, Switzerland.
    Godfray, H. C. J.
    Centre for Population Biology, Department of Biology, Imperial College at Silwood Park, Ascot, Berks SL5 7PY, United Kingdom.
    Van Savage, M.
    Bauer Center for Genomics Research, Harvard University, Sherman, Bauer Laboratory, 7 Divinity Avenue, Cambridge, MA 02138, United States.
    Body sizes of hosts and parasitoids in individual feeding relationships2005In: Proceedings of the National Academy of Sciences of the United States of America, ISSN 0027-8424, E-ISSN 1091-6490, Vol. 102, no 3, p. 684-689Article in journal (Refereed)
    Abstract [en]

    In a natural community of 49 species (12 species of aphids and 37 species of their parasitoids), body lengths of 2,151 parasitoid individuals were, to an excellent approximation, related to the body lengths of their individual aphid hosts by a power law with an exponent close to 3/4. Two alternative models predict this exponent. One is based on surface area to volume relationships. The other is based on recent developments in metabolic ecology. Both models require a changing ratio (in both host and parasitoid) of length to diameter with increasing body length. These changing ratios are manifested differently in the two models and result in testably different predictions for the scaling of body form with increasing size. The estimated exponent of 3/4 for the relationship between individual host body size and individual parasitoid body size degrades to an exponent of nearly 1/2, and the scatter in the relationship between aphid and parasitoid body length is substantially increased, if the average length of a parasitoid species is examined as a function of the average length of its aphid host species instead of using measurements of individuals.

    allometry | aphids | development | metabolism | weight–length relations

    Explaining the size of organisms is an enduring challenge to ecologists and evolutionary biologists (1, 2) to cellular and developmental biologists (3). Ecological studies of the relationship between consumer and resource body sizes (4–8) usually assume that the average body size of a species is an adequate approximation to the size of the individuals taking part in a particular trophic interaction. However, individuals of different size within one resource species may be selectively consumed by different consumer species or individuals of different size within a given consumer species. Vice versa, individuals of different size within one consumer species may selectively consume resource species of different average size or individuals of different size within a given resource species. To understand the relationship between consumer and resource body sizes, it is important that the data correctly represent the body sizes of the consumers and resources involved in the trophic interactions. What are the consequences of focusing on body sizes of consumer and resource individuals vs. average sizes of taxonomic species for understanding feeding relations in natural communities? To answer this question, here we report quantitative field data on body sizes in individual events of parasitism.

    Animal consumers are often considerably larger than their prey (4), whereas parasites and pathogens are generally much smaller than their resources (5). Solitary insect parasitoids that complete their larval development on or in the body of other living insects, and require just a single host to complete development, lie between these extremes: they are often similar in size to their insect hosts. Parasitoid and host body sizes are well suited to shed light on the role of individual differences in consumer-resource body size relations because the variations in both parasitoid and host body sizes are likely to be of comparable magnitude.

    Parasitoids are important components of all terrestrial ecological communities. Probably 1–2 million species are parasitoids (9), and they are thus a significant fraction of all species on this planet. As potentially important regulators of their host populations, parasitoids are intensively used in biological control (10). Most prior studies of the body sizes of hosts and parasitoids consider only a single species of host. The few studies (11–14) that consider host–parasitoid size relationships of multiple species have only one data point per species.

    We studied quantitatively the relationship between final individual aphid host and parasitoid body length in a natural aphid-parasitoid community with multiple species of hosts and parasitoids. The objectives of the study were to (i) describe the relationship between final aphid host and parasitoid body size, (ii) analyze the consequences of focusing on body sizes of consumer and resource individuals vs. average sizes of taxonomic species for the apparent relationship between final aphid host and parasitoid body size, and (iii) offer two alternative explanations for the relationship between final aphid host and parasitoid body size. We hope that future studies will discriminate between these alternative explanations.

  • 8.
    Cohen, Joel
    et al.
    The Rockefeller University and Columbia University, New York, USA.
    Jonsson, Tomas
    The Rockefeller University, New York, USA.
    Carpenter, Stephen R.
    Center for Limnology, University of Wisconsin, Madison, USA.
    Ecological community description using the food web, species abundance, and body size2003In: Proceedings of the National Academy of Sciences of the United States of America, ISSN 0027-8424, E-ISSN 1091-6490, Vol. 100, no 4, p. 1781-1786Article in journal (Refereed)
  • 9.
    Curtsdotter, Alva
    et al.
    University of Skövde, School of Bioscience. Department of Ecology, Swedish University of Agricultural Sciences, Uppsala, Sweden / Department of Environmental Sciences, Emory University, Atlanta, GA, Georgia, United States.
    Banks, H. Thomas
    Center for Research in Scientific Computation, North Carolina State University, Raleigh, NC, United States.
    Banks, John E.
    Undergraduate Research Opportunities Center (UROC), California State University, Monterey Bay, Seaside, CA, United States.
    Jonsson, Mattias
    Department of Ecology, Swedish University of Agricultural Sciences, Uppsala, Sweden.
    Jonsson, Tomas
    University of Skövde, School of Bioscience. University of Skövde, The Systems Biology Research Centre. Department of Ecology, Swedish University of Agricultural Sciences, Uppsala, Sweden .
    Laubmeier, Amanda N.
    Center for Research in Scientific Computation, North Carolina State University, Raleigh, NC, United States.
    Traugott, Michael
    Mountain Agriculture Research Unit, Institute of Ecology, University of Innsbruck, Innsbruck, Austria.
    Bommarco, Riccardo
    Department of Ecology, Swedish University of Agricultural Sciences, Uppsala, Sweden.
    Ecosystem function in predator-prey food webs: confronting dynamic models with empirical data2019In: Journal of Animal Ecology, ISSN 0021-8790, E-ISSN 1365-2656, Vol. 88, no 2, p. 196-210Article in journal (Refereed)
    Abstract [en]

    Most ecosystem functions and related services involve species interactions across trophic levels, for example, pollination and biological pest control. Despite this, our understanding of ecosystem function in multitrophic communities is poor, and research has been limited to either manipulation in small communities or statistical descriptions in larger ones. Recent advances in food web ecology may allow us to overcome the trade-off between mechanistic insight and ecological realism. Molecular tools now simplify the detection of feeding interactions, and trait-based approaches allow the application of dynamic food web models to real ecosystems. We performed the first test of an allometric food web model's ability to replicate temporally nonaggregated abundance data from the field and to provide mechanistic insight into the function of predation. We aimed to reproduce and explore the drivers of the population dynamics of the aphid herbivore Rhopalosiphum padi observed in ten Swedish barley fields. We used a dynamic food web model, taking observed interactions and abundances of predators and alternative prey as input data, allowing us to examine the role of predation in aphid population control. The inverse problem methods were used for simultaneous model fit optimization and model parameterization. The model captured >70% of the variation in aphid abundance in five of ten fields, supporting the model-embodied hypothesis that body size can be an important determinant of predation in the arthropod community. We further demonstrate how in-depth model analysis can disentangle the likely drivers of function, such as the community's abundance and trait composition. Analysing the variability in model performance revealed knowledge gaps, such as the source of episodic aphid mortality, and general method development needs that, if addressed, would further increase model success and enable stronger inference about ecosystem function. The results demonstrate that confronting dynamic food web models with abundance data from the field is a viable approach to evaluate ecological theory and to aid our understanding of function in real ecosystems. However, to realize the full potential of food web models, in ecosystem function research and beyond, trait-based parameterization must be refined and extended to include more traits than body size. © 2018 The Authors. Journal of Animal Ecology © 2018 British Ecological Society

  • 10.
    Ebenman, Bo
    et al.
    Department of Biology, Linköping University, Linköping, Sweden.
    Johansson, Annie
    Department of Biology, Linköping University, Linköping, Sweden.
    Jonsson, Tomas
    Department of Biology, Linköping University, Linköping, Sweden.
    Wennergren, Uno
    Department of Biology, Linköping University, Linköping, Sweden.
    Evolution of stable population dynamics through natural selection1996In: Proceedings of the Royal Society of London. Biological Sciences, ISSN 0962-8452, E-ISSN 1471-2954, Vol. 263, no 1374, p. 1145-1151Article in journal (Refereed)
  • 11.
    Ebenman, Bo
    et al.
    Department of Biology, IFM, Linköping University, SE-58183 Linköping, Sweden.
    Jonsson, Tomas
    University of Skövde, School of Life Sciences.
    Using community viability analysis to identify fragile systems and keystone species2005In: Trends in Ecology & Evolution, ISSN 0169-5347, E-ISSN 1872-8383, Vol. 20, no 10, p. 568-575Article in journal (Refereed)
    Abstract [en]

    Owing to interdependences among species in ecological communities, the loss of one species can trigger a cascade of secondary extinctions with potentially dramatic effects on the functioning and stability of the community. It is, therefore, important to assess the risk and likely extent of secondary extinctions. Community viability analysis is a new technique that can be used to accomplish this goal. The analysis can also be used to identify fragile community structures and keystone species and, hence, to provide guidelines for conservation priorities. Here, we describe the principles underlying community viability analysis and review its contributions to our understanding of the response of ecological communities to species loss.

  • 12.
    Gagic, Vesna
    et al.
    Department of Ecology, Swedish University of Agricultural Sciences, Uppsala, Sweden.
    Bartomeus, Ignasio
    Department of Ecology, Swedish University of Agricultural Sciences, Uppsala, Sweden / Departamento de Ecología Integrativa, Estación Biológica de Doñana (EBD-CSIC), Sevilla, Spain.
    Jonsson, Tomas
    Department of Ecology, Swedish University of Agricultural Sciences, Uppsala, Sweden.
    Taylor, Astrid
    Department of Ecology, Swedish University of Agricultural Sciences, Uppsala, Sweden.
    Winqvist, Camilla
    Department of Ecology, Swedish University of Agricultural Sciences, Uppsala, Sweden.
    Fischer, Christina
    Department of Ecology and Ecosystem Management, Technische Universität München, Restoration Ecology, Germany.
    Slade, Eleanor M.
    Department of Zoology, University of Oxford, Oxford, UK.
    Steffan-Dewenter, Ingolf
    Department of Animal Ecology and Tropical Biology, Biocentre, University of Würzburg, Würzburg, Germany.
    Emmerson, Mark
    School of Biological Sciences, Queen's University Belfast, Medical Biology Centre, Belfast, UK.
    Potts, Simon G.
    School of Agriculture, Policy and Development, Reading University, Reading, UK.
    Tscharntke, Teja
    Department of Agroecology, University of Göttingen, Göttingen, Germany.
    Weisser, Wolfgang
    Terrestrial Ecology Research Group, Department of Ecology and Ecosystem Management, Center for Food and Life Sciences Weihenstephan, Technische Universität München, Freising, Germany.
    Bommarco, Riccardo
    Department of Ecology, Swedish University of Agricultural Sciences, Uppsala, Sweden.
    Functional identity and diversity of animals predict ecosystem functioning better than species-based indices2015In: Proceedings of the Royal Society of London. Biological Sciences, ISSN 0962-8452, E-ISSN 1471-2954, Vol. 282, no 1801, article id UNSP 20142620Article in journal (Refereed)
  • 13.
    Jacob, Ute
    et al.
    Institute for Hydrobiology and Fisheries Science, University of Hamburg, Hamburg, Germany.
    Jonsson, Tomas
    Population Ecology Unit, Institute for Ecology, Uppsala, Sweden.
    Berg, Sofia
    EnviroPlanning AB, Göteborg, Sweden.
    Brey, Thomas
    Alfred Wegener Institute for Polar and Marine Research, Bremerhaven, Germany.
    Eklöf, Anna
    Department of Physics, Chemistry and Biology (IFM), Linköping University, Linköping, Sweden.
    Mintenbeck, Katja
    Alfred Wegener Institute for Polar and Marine Research, Bremerhaven, Germany.
    Möllmann, Christian
    Institute for Hydrobiology and Fisheries Science, University of Hamburg, Hamburg, Germany.
    Morissette, Lyne
    M-Expertise Marine, Sainte-Luce, Canada.
    Rau, Andrea
    Johann Heinrich von Thünen Institute for Baltic Sea Fisheries, Rostock, Germany.
    Petchey, Owen
    Institute of Evolutionary Biology and Environmental Studies, University of Zurich, Zurich, Switzerland.
    Valuing biodiversity and ecosystem services in a complex marine ecosystem2015In: Aquatic Functional Biodiversity: An Ecological and Evolutionary Perspective / [ed] Andrea Belgrano, Guy Woodward & Ute Jacob, London: Academic Press, 2015, p. 189-207Chapter in book (Refereed)
  • 14.
    Jacob, Ute
    et al.
    University of Hamburg, Inst Hydrobiol & Fisheries Sci, Hamburg, Germany.
    Thierry, Aaron
    University of Sheffield, Dept Anim & Plant Sci, Western Bank, Sheffield S10 2TN, S Yorkshire, England / Microsoft Res, Cambridge, England.
    Brose, Ulrich
    Georg-August University Göttingen JF Blumenbach Inst Zool & Anthropol, Syst Conservat Biol Grp, Göttingen, Germany.
    Arntz, Wofe E.
    Alfred Wegener Inst Polar & Marine Res, Bremerhaven, Germany.
    Berg, Sofia
    University of Skövde, School of Life Sciences. University of Skövde, The Systems Biology Research Centre.
    Brey, Thomas
    Alfred Wegener Institute for Polar and Marine Research.
    Fetzer, Ingo
    UFZ Helmholtz Ctr Environm Res, Dept Environm Microbiol, Leipzig, Germany.
    Jonsson, Tomas
    University of Skövde, School of Life Sciences. University of Skövde, The Systems Biology Research Centre.
    Mintenbeck, Katja
    Alfred Wegener Inst Polar & Marine Res, Bremerhaven, Germany.
    Möllmann, Christian
    Univ Hamburg, Inst Hydrobiol & Fisheries Sci, Hamburg, Germany.
    Petchey, Owen
    Univ Zurich, Inst Evolutionary Biol & Environm Studies, Zurich, Switzerland.
    Riede, Jens O.
    Univ Gottingen, JF Blumenbach Inst Zool & Anthropol, Syst Conservat Biol Grp, Gottingen, Germany.
    Dunne, Jennifer A.
    Santa Fe Inst, Santa Fe, NM 87501 USA / Pacific Ecoinformat & Computat Ecol Lab, Berkeley, CA USA.
    The Role of Body Size in Complex Food Webs: A Cold Case2011In: Advances in Ecological Research, ISSN 0065-2504, E-ISSN 2163-582X, Vol. 45, p. 181-223Article in journal (Refereed)
    Abstract [en]

    Human-induced habitat destruction, overexploitation, introduction of alien species and climate change are causing species to go extinct at unprecedented rates, from local to global scales. There are growing concerns that these kinds of disturbances alter important functions of ecosystems. Our current understanding is that key parameters of a community (e.g. its functional diversity, species composition, and presence/absence of vulnerable species) reflect an ecological network’s ability to resist or rebound from change in response to pressures and disturbances, such as species loss. If the food web structure is relatively simple, we can analyse the roles of different species interactions in determining how environmental impacts translate into species loss. However, when ecosystems harbour species-rich communities, as is the case in most natural systems, then the complex network of ecological interactions makes it a far more challenging task to perceive how species’ functional roles influence the consequences of species loss. One approach to deal with such complexity is to focus on the functional traits of species in order to identify their respective roles: for instance, large species seem to be more susceptible to extinction than smaller species. Here, we introduce and analyse the marine food web from the high Antarctic Weddell Sea Shelf to illustrate the role of species traits in relation to network robustness of this complex food web. Our approach was threefold: firstly, we applied a new classification system to all species, grouping them by traits other than body size; secondly, we tested the relationship between body size and food web parameters within and across these groups and finally, we calculated food web robustness. We addressed questions regarding (i) patterns of species functional/trophic roles, (ii) relationships between species functional roles and body size and (iii) the role of species body size in terms of network robustness. Our results show that when analyzing relationships between trophic structure, body size and network structure, the diversity of predatory species types needs to be considered in future studies.

  • 15.
    Jonsson, Annie
    et al.
    University of Skövde, School of Bioscience. University of Skövde, The Systems Biology Research Centre.
    Jonsson, Tomas
    University of Skövde, School of Bioscience. University of Skövde, The Systems Biology Research Centre.
    Toräng, Per
    University of Skövde, School of Bioscience. University of Skövde, The Systems Biology Research Centre.
    Utvärdering av Hornborgasjöns restaurering: måluppfyllelse och effekter på biologisk mångfald med fokus på vegetation och fågelfauna2017Report (Other academic)
    Abstract [sv]

    Hornborgasjön räknas idag som en av Sveriges rikaste fågelsjöar och är internationellt utpekad som en av Sveriges värdefullaste våtmarker. Sjön har stor betydelse som både rast- och häckplats för en mängd fågelarter. Området är också av stort intresse för friluftslivet och som ett levande kulturlandskap. Under de senaste 150 åren har Hornborgasjön genomgått stora förändringar. En serie av sjösänkningar under 1800 och 1900-talen ledde till kraftig igenväxning och följdes av ett storskaligt restaureringsprojekt i senare tid. Syftet med Hornborgasjöns restaurering var att säkerställa Hornborgasjöns framtid som fågelsjö. Restaureringen är ett av Sveriges största naturvårdsprojekt. I denna rapport har vi utvärderat hur Hornborgasjöns restaurering påverkat vegetation och fågelfauna. Syftet var att analysera om och till vilken grad de biologiska målen med restaureringen uppnåtts.För att utvärdera måluppfyllelsen har vi i första hand jämfört olika naturtypers utbredning mellan åren 1905 och 2010 samt förändringar i fågelfaunan under flera tidsperioder. Analyser av vegetationskartor visar att vass- och buskområden kraftigt reducerats och att en stor öppen vattenspegel och omgivande mader återskapats. Våtmarksfåglarnas numerär har generellt sett återhämtat sig från igenväxningsperioden och är för vissa arter till och med större än vid förra sekelskiftet. För vissa naturtyper och fågelarter, som till exempel vassområden och häckande vadare, är dagens situation dock inte i linje med målen. Det står ändå klart att det övergripande målet och många av de mer specifika delmålen har uppfyllts så att Hornborgasjön idag är en levande våtmark med stort antal häckande och rastande fågelarter.I analyser av fågeldata från senare tid finns indikationer på negativa trender som man behöver vara observant på för att för framtiden säkra en biologiskt rik Hornborgasjö. En utmaning för denna utvärdering har dock varit bristen på högkvalitativa och jämförbara data att basera analyserna på. Vi belyser därför vikten av att ha ett fungerande övervakningssystem som kontinuerligt följer upp statusen i ekosystemet.

  • 16.
    Jonsson, Tomas
    University of Skövde, School of Bioscience. University of Skövde, The Systems Biology Research Centre. Department of Ecology, Swedish University of Agricultural Sciences, Uppsala, Sweden.
    Conditions for Eltonian Pyramids in Lotka-Volterra Food Chains2017In: Scientific Reports, ISSN 2045-2322, E-ISSN 2045-2322, Vol. 7, article id 10912Article in journal (Refereed)
    Abstract [en]

    In ecological communities consumers (excluding parasites and parasitoids) are in general larger and less numerous than their resource. This results in a well-known observation known as 'Eltonian pyramids' or the ` pyramid of numbers', and metabolic arguments suggest that this pattern is independent of the number of trophic levels in a system. At the same time, Lotka-Volterra (LV) consumer-resource models are a frequently used tool to study many questions in community ecology, but their capacity to produce Eltonian pyramids has not been formally analysed. Here, I address this knowledge gap by investigating if and when LV food chain models give rise to Eltonian pyramids. I show that Eltonian pyramids are difficult to reproduce without density-dependent mortality in the consumers, unless biologically plausible relationships between mortality rate and interaction strength are taken into account.

  • 17.
    Jonsson, Tomas
    University of Skövde, School of Bioscience. University of Skövde, The Systems Biology Research Centre. Department of Ecology, Swedish University of Agricultural Sciences, Uppsala, Sweden.
    Metabolic theory predicts animal self-thinning2017In: Journal of Animal Ecology, ISSN 0021-8790, E-ISSN 1365-2656, Vol. 86, no 3, p. 645-653Article in journal (Refereed)
    Abstract [en]
    1. The metabolic theory of ecology (MTE) predicts observed patterns in ecology based on metabolic rates of individuals. The theory is influential but also criticized for a lack of firm empirical evidence confirming MTE's quantitative predictions of processes, e.g. outcome of competition, at population or community level.
    2. Self-thinning is a well-known population level phenomenon among plants, but a much less studied phenomenon in animal populations and no consensus exists on what a universal thinning slope for animal populations might be, or if it exists.
    3. The goal of this study was to use animal self-thinning as a tool to test population-level predictions from MTE, by analysing (i) if self-thinning can be induced in populations of house crickets (Acheta domesticus) and (ii) if the resulting thinning trajectories can be predicted from metabolic theory, using estimates of the species-specific metabolic rate of A. domesticus.
    4. I performed a laboratory study where the growth of A. domesticus was followed, from hatching until emergence as adults, in 71 cohorts of five different starting densities.
    5. Ninety-six per cent of all cohorts in the three highest starting densities showed evidence of self-thinning, with estimated thinning slopes in general being remarkably close to that expected under metabolic constraints: A cross-sectional analysis of all data showing evidence of self-thinning produced an ordinary least square (OLS) slope of −1·11, exactly that predicted from specific metabolic allometry of A. domesticus. This result is furthermore supported by longitudinal analyses, allowing for independent responses within cohorts, producing a mean OLS slope across cohorts of −1·13 and a fixed effect linear mixed effects models slope of −1·09. Sensitivity analysis showed that these results are robust to how the criterion for on-going self-thinning was defined. Finally, also as predicted by metabolic theory, temperature had a negative effect on the thinning intercept, producing an estimate of the activation energy identical to that suggested by MTE.
    6. This study demonstrates a direct link between the metabolic rate of individuals and a population-level ecological process and as such provides strong support for research that aims to integrate body mass, via its effect on metabolism, consumption and competition, into models of populations and communities.
  • 18.
    Jonsson, Tomas
    Swedish University of Agricultural Sciences.
    Trophic links and the relationship between predator and prey body sizes in food webs2014In: Community Ecology, ISSN 1585-8553, Vol. 15, p. 54-64Article in journal (Refereed)
  • 19.
    Jonsson, Tomas
    et al.
    University of Skövde, School of Bioscience. University of Skövde, The Systems Biology Research Centre. Department of Ecology, Swedish University of Agricultural Sciences, Uppsala, Sweden.
    Berg, Sofia
    University of Skövde, School of Bioscience. University of Skövde, The Systems Biology Research Centre. Department of Physics, Chemistry and Biology, Division of Theoretical Biology, Linköping University, Linköping, Sweden.
    Emmerson, Mark
    School of Biological Sciences, Queen's University Belfast, Belfast, UK.
    Pimenov, Alexander
    Environmental Research Institute, University College Cork, Lee Road, Cork, Ireland / Weierstrass Institute, Berlin, Germany.
    The context dependency of species keystone status during food web disassembly2015In: Food Webs, ISSN 2352-2496, Vol. 5, p. 1-10Article in journal (Refereed)
  • 20.
    Jonsson, Tomas
    et al.
    University of Skövde, School of Bioscience. University of Skövde, The Systems Biology Research Centre. Dept of Ecology, Swedish Univ. of Agricultural Sciences, Uppsala, Sweden.
    Berg, Sofia
    University of Skövde, School of Bioscience. University of Skövde, The Systems Biology Research Centre. Dept of Physics, Chemistry and Biology, Div. of Theoretical Biology, Linköping Univ., Linköping, Sweden.
    Pimenov, Alexander
    Environmental Res. Inst., Univ. College Cork, Cork, Ireland / Weierstrass Inst., Berlin, Germany.
    Palmer, Catherine
    Environmental Res. Inst., Univ. College Cork, Cork, Ireland.
    Emmerson, Mark
    School of Biological Sciences, Queen's Univ. Belfast, Belfast, United Kingdom.
    The reliability of R50 as a measure of vulnerability of food webs to sequential species deletions2015In: Oikos, ISSN 0030-1299, E-ISSN 1600-0706, Vol. 124, no 4, p. 446-457Article in journal (Refereed)
  • 21.
    Jonsson, Tomas
    et al.
    University of Skövde, School of Life Sciences.
    Cohen, Joel E.
    Carpenter, Stephen R.
    Food webs, body size, and species abundance in ecological community description2005In: Advances in Ecological Research, ISSN 0065-2504, E-ISSN 2163-582X, Vol. 36, p. 1-83Article in journal (Refereed)
  • 22.
    Jonsson, Tomas
    et al.
    Department of Biology, Linköping University, Linköping, Sweden.
    Ebenman, Bo
    Department of Biology, Linköping University, Linköping, Sweden.
    Effects of predator-prey body size ratios on the stability of food chains1998In: Journal of Theoretical Biology, ISSN 0022-5193, E-ISSN 1095-8541, Vol. 193, no 3, p. 407-417Article in journal (Refereed)
  • 23.
    Jonsson, Tomas
    et al.
    University of Skövde, School of Bioscience. University of Skövde, The Systems Biology Research Centre. Department of Ecology, Swedish University of Agricultural Sciences, Uppsala, Sweden.
    Kaartinen, Riikka
    Department of Ecology, Swedish University of Agricultural Sciences, Uppsala, Sweden.
    Jonsson, Mattias
    Department of Ecology, Swedish University of Agricultural Sciences, Uppsala, Sweden.
    Bommarco, Riccardo
    Department of Ecology, Swedish University of Agricultural Sciences, Uppsala, Sweden.
    Predictive power of food web models based on body size decreases with trophic complexity2018In: Ecology Letters, ISSN 1461-023X, E-ISSN 1461-0248, Vol. 21, no 5, p. 702-712Article in journal (Refereed)
    Abstract [en]

    Food web models parameterised using body size show promise to predict trophic interaction strengths (IS) and abundance dynamics. However, this remains to be rigorously tested in food webs beyond simple trophic modules, where indirect and intraguild interactions could be important and driven by traits other than body size. We systematically varied predator body size, guild composition and richness in microcosm insect webs and compared experimental outcomes with predictions of IS from models with allometrically scaled parameters. Body size was a strong predictor of IS in simple modules (r(2)=0.92), but with increasing complexity the predictive power decreased, with model IS being consistently overestimated. We quantify the strength of observed trophic interaction modifications, partition this into density-mediated vs. behaviour-mediated indirect effects and show that model shortcomings in predicting IS is related to the size of behaviour-mediated effects. Our findings encourage development of dynamical food web models explicitly including and exploring indirect mechanisms.

  • 24.
    Jonsson, Tomas
    et al.
    University of Skövde, School of Life Sciences. University of Skövde, The Systems Biology Research Centre.
    Karlsson, Patrik
    University of Skövde, School of Life Sciences. University of Skövde, The Systems Biology Research Centre.
    Jonsson, Annie
    University of Skövde, School of Life Sciences. University of Skövde, The Systems Biology Research Centre.
    Food web structure affects the extinction risk of species in ecological communities2006In: Ecological Modelling, ISSN 0304-3800, E-ISSN 1872-7026, Vol. 199, no 1, p. 93-106Article in journal (Refereed)
    Abstract [en]

    This paper studies the effect of food web structure on the extinction risk of species. We examine 793 different six-species food web structures with different number, position and strength of trophic links and expose them to stochasticity in a model with Lotka–Volterra predator–prey dynamics. The characteristics of species (intrinsic rates of increase as well as intraspecific density dependence) are held constant, but the interactions with other species and characteristics of the food web are varied.

    Extinctions of producer species occurred but were rare. Species at all trophic levels went extinct in communities with strong interactions as compared to communities with no strong interactions where only the secondary consumer went extinct. Extinction of a species directly involved in a strong interaction was more frequent than extinctions of species not directly involved in strong interactions (here termed direct and indirect extinctions, respectively). In model webs where both direct and indirect extinctions occurred, roughly 20% were indirect extinctions. The probability of indirect extinctions decreased with number of links. It is concluded that not just the presence of strong interactions but also their position and direction can have profound effects on extinction risk of species.

    Three principal components, based on 11 different food web metrics, explained 76.6% of the variation in trophic structure among food webs that differed in the number and position, but not strength, of trophic links. The extinction risk of consumer species was closely correlated to at least two of the three principal components, indicating that extinction risk of consumer species were affected by food web structure. The existence of a relationship between food web structure and extinction risk of a species was confirmed by a regression tree analysis and a complementary log-linear analysis. These analyses showed that extinction of consumer species were affected by the position of strong interactions and a varying number of other food web metrics, different for intermediate and top species. Furthermore, the degree to which the equilibrium abundance of a species is affected by a press perturbation is an indication of the risk of extinction that this species faces when exposed to environmental stochasticity. It is concluded that extinction risk of a species is determined in a complicated way by an interaction among species characteristics, food web structure and the type of disturbance.

  • 25.
    Jonsson, Tomas
    et al.
    University of Skövde, The Systems Biology Research Centre. University of Skövde, School of Life Sciences.
    Karlsson, Patrik
    University of Skövde, The Systems Biology Research Centre.
    Jonsson, Annie
    University of Skövde, The Systems Biology Research Centre. University of Skövde, School of Life Sciences.
    Trophic interactions affect the population dynamics and risk of extinction of basal species in food webs2010In: Ecological Complexity: An International Journal on Biocomplexity in the Environment and Theoretical Ecology, ISSN 1476-945X, E-ISSN 1476-9840, Vol. 7, no 1, p. 60-68Article in journal (Refereed)
    Abstract [en]

    This paper addresses effects of trophic complexity on basal species, in a Lotka–Volterra model with stochasticity. We use simple food web modules, with three trophic levels, and expose every species to random environmental stochasticity and analyze (1) the effect of the position of strong trophic interactions on temporal fluctuations in basal species’ abundances and (2) the relationship between fluctuation patterns and extinction risk. First, the numerical simulations showed that basal species do not simply track the environment, i.e. species dynamics do not simply mirror the characteristics of the applied environmental stochasticity. Second, the extinction risk of species was related to the fluctuation patterns of the species.

    More specifically, we show (i) that despite being forced by random stochasticity without temporal autocorrelation (i.e. white noise), there is significant temporal autocorrelation in the time series of all basal species’ abundances (i.e. the spectra of basal species are red-shifted), (ii) the degree of temporal autocorrelation in basal species time series is affected by food web structure and (iii) the degree of temporal autocorrelation tend to be correlated to the extinction risks of basal species.

    Our results emphasize the role of food web structure and species interactions in modifying the response of species to environmental variability. To shed some light on the mechanisms we compare the observed pattern in abundances of basal species with analytically predicted patterns and show that the change in the predicted pattern due to the addition of strong trophic interactions is correlated to the extinction risk of the basal species. We conclude that much remain to be understood about the mechanisms behind the interaction among environmental variability, species interactions, population dynamics and vulnerability before we quantitatively can predict, for example, effects of climate change on species and ecological communities. Here, however, we point out a new possible approach for identifying species that are vulnerable to environmental stochasticity by checking the degree of temporal autocorrelation in the time series of species. Increased autocorrelation in population fluctuations can be an indication of increased extinction risk.

  • 26.
    Jonsson, Tomas
    et al.
    University of Skövde, School of Bioscience. University of Skövde, The Systems Biology Research Centre. Department of Ecology, Swedish University of Agricultural Sciences, Uppsala, Sweden.
    Setzer, Malin
    University of Skövde, School of Bioscience. University of Skövde, The Systems Biology Research Centre.
    A freshwater predator hit twice by effects of warming across trophic levels2015In: Nature Communications, ISSN 2041-1723, E-ISSN 2041-1723, Vol. 6, article id 5992Article in journal (Refereed)
  • 27.
    Jonsson, Tomas
    et al.
    University of Skövde, School of Life Sciences. University of Skövde, The Systems Biology Research Centre. Swedish University of Agricultural Sciences, Sweden.
    Setzer, Malin
    University of Skövde, School of Life Sciences. University of Skövde, The Systems Biology Research Centre.
    Pope, John G.
    Technical University of Denmark, Denmark..
    Sandstrom, Alfred
    Swedish University of Agricultural Sciences, Sweden.
    Addressing catch mechanisms in gillnets improves modeling of selectivity and estimates of mortality rates: a case study using survey data on an endangered stock of Arctic char2013In: Canadian Journal of Fisheries and Aquatic Sciences, ISSN 0706-652X, E-ISSN 1205-7533, Vol. 70, no 10, p. 1477-1487Article in journal (Refereed)
    Abstract [en]

    Estimation of fish stock size distributions from survey data requires knowledge about gear selectivity. However, selectivity models rest on assumptions that seldom are analyzed. Departures from these can lead to misinterpretations and biased management recommendations. Here, we use survey data on great Arctic char (Salvelinus umbla) to analyze how correcting for entanglement of fish and nonisometric growth might improve estimates of selectivity curves, and subsequently estimates of size distribution and age-specific mortality. Initial selectivity curves, using the entire data set, were wide and asymmetric, with poor model fits. Removing potentially nonmeshed fish had the greatest positive effect on model fit, resulting in much narrower and less asymmetric selection curves, while attempting to take nonisometric growth into account, by using girth rather than length, improved model fit but not as much. Using simulations we show that correcting for both entanglement and size selectivity produces accurate estimates of mortality rates, while correcting for size selectivity only does not. Our study demonstrates an approach that increases the accuracy of estimates of fish size distributions and mortality rates from survey data.

  • 28.
    Kaneryd, Linda
    et al.
    Division of Theoretical Biology, Department of Physics, Chemistry and Biology, Linköping University, Linköping, Sweden.
    Borrvall, Charlotte
    Division of Theoretical Biology, Department of Physics, Chemistry and Biology, Linköping University, Linköping, Sweden.
    Berg, Sofia
    University of Skövde, School of Life Sciences. University of Skövde, The Systems Biology Research Centre. Division of Theoretical Biology, Department of Physics, Chemistry and Biology, Linköping University, Linköping, Sweden.
    Curtsdotter, Alva
    Division of Theoretical Biology, Department of Physics, Chemistry and Biology, Linköping University, Linköping, Sweden.
    Eklöf, Anna
    Division of Theoretical Biology, Department of Physics, Chemistry and Biology, Linköping University, Linköping, Sweden.
    Hauzy, Céline
    Division of Theoretical Biology, Department of Physics, Chemistry and Biology, Linköping University, Linköping, Sweden / Laboratoire Ecologie et Evolution, Université Pierre et Marie Curie, Paris, France.
    Jonsson, Tomas
    University of Skövde, School of Life Sciences. University of Skövde, The Systems Biology Research Centre.
    Münger, Peter
    Division of Theoretical Biology, Department of Physics, Chemistry and Biology, Linköping University, Linköping, Sweden.
    Setzer, Malin
    University of Skövde, School of Life Sciences. University of Skövde, The Systems Biology Research Centre. Division of Theoretical Biology, Department of Physics, Chemistry and Biology, Linköping University, Linköping, Sweden.
    Säterberg, Torbjörn
    Division of Theoretical Biology, Department of Physics, Chemistry and Biology, Linköping University, Linköping, Sweden.
    Ebenman, Bo
    Division of Theoretical Biology, Department of Physics, Chemistry and Biology, Linköping University, Linköping, Sweden.
    Species-rich ecosystems are vulnerable to cascading extinctions in an increasingly variable world2012In: Ecology and Evolution, ISSN 2045-7758, E-ISSN 2045-7758, Vol. 2, no 4, p. 858-874Article in journal (Refereed)
    Abstract [en]

    Global warming leads to increased intensity and frequency of weather extremes. Such increased environmental variability might in turn result in increased variation in the demographic rates of interacting species with potentially important consequences for the dynamics of food webs. Using a theoretical approach, we here explore the response of food webs to a highly variable environment.We investigate how species richness and correlation in the responses of species to environmental fluctuations affect the risk of extinction cascades. We find that the risk of extinction cascades increases with increasing species richness, especially when correlation among species is low. Initial extinctions of primary producer species unleash bottom-up extinction cascades, especially in webs with specialist consumers. In this sense, species-rich ecosystems are less robust to increasing levels of environmental variability than species-poor ones. Our study thus suggests that highly speciesrich ecosystems such as coral reefs and tropical rainforests might be particularly vulnerable to increased climate variability.

  • 29.
    Karlsson, Patrik
    et al.
    University of Skövde, School of Life Sciences. University of Skövde, The Systems Biology Research Centre.
    Jonsson, Tomas
    University of Skövde, School of Life Sciences. University of Skövde, The Systems Biology Research Centre.
    Jonsson, Annie
    University of Skövde, School of Life Sciences. University of Skövde, The Systems Biology Research Centre.
    Food web structure and interaction strength pave the way for vulnerability to extinction2007In: Journal of Theoretical Biology, ISSN 0022-5193, E-ISSN 1095-8541, Vol. 249, no 1, p. 77-92Article in journal (Refereed)
    Abstract [en]

    This paper focuses on how food web structure and interactions among species affects the vulnerability, due to environmental variability, to extinction of species at different positions in model food webs. Vulnerability is here not measured by a traditional extinction threshold but is instead inspired by the IUCN criteria for endangered species: an observed rapid decline in population abundance. Using model webs influenced by stochasticity with zero autocorrelation, we investigate the ecological determinants of species vulnerability, i.e. the trophic interactions between species and food web structure and how these interact with the risk of sudden drops in abundance of species. We find that (i) producers fulfil the criterion of vulnerable species more frequently than other species, (ii) food web structure is related to vulnerability, and (iii) the vulnerability of species is greater when involved in a strong trophic interaction than when not. We note that our result on the relationship between extinction risk and trophic position of species contradict previous suggestions and argue that the main reason for the discrepancy probably is due to the fact that we study the vulnerability to environmental stochasticity and not extinction risk due to overexploitation, habitat destruction or interactions with introduced species. Thus, we suggest that the vulnerability of species to environmental stochasticity may be differently related to trophic position than the vulnerability of species to other factors.

    Earlier research on species extinctions has looked for intrinsic traits of species that correlate with increased vulnerability to extinction. However, to fully understand the extinction process we must also consider that species interactions may affect vulnerability and that not all extinctions are the result of long, gradual reductions in species abundances. Under environmental stochasticity (which importance frequently is assumed to increase as a result of climate change) and direct and indirect interactions with other species some extinctions may occur rapidly and apparently unexpectedly. To identify the first declines of population abundances that may escalate and lead to extinctions as early as possible, we need to recognize which species are at greatest risk of entering such dangerous routes and under what circumstances. This new perspective may contribute to our understanding of the processes leading to extinction of populations and eventually species. This is especially urgent in the light of the current biodiversity crisis where a large fraction of the world's biodiversity is threatened.

  • 30.
    Kollberg, Ida
    et al.
    Swedish University of Agricultural Sciences, Department of Ecology, Uppsala, Sweden.
    Bylund, H.
    Swedish University of Agricultural Sciences, Department of Ecology, Uppsala, Sweden.
    Jonsson, Tomas
    Swedish University of Agricultural Sciences, Department of Ecology, Uppsala, Sweden.
    Schmidt, A.
    Max Planck Institute for Chemical Ecology, Department of Biochemistry, Jena, Germany.
    Gershenzon, J.
    Max Planck Institute for Chemical Ecology, Department of Biochemistry, Jena, Germany.
    Björkman, C.
    Swedish University of Agricultural Sciences, Department of Ecology, Uppsala, Sweden.
    Temperature affects insect outbreak risk through tritrophic interactions mediated by plant secondary compounds2015In: Ecosphere, ISSN 2150-8925, E-ISSN 2150-8925, Vol. 6, no 6, article id 102Article in journal (Refereed)
  • 31. McLaughlin, Órla B.
    et al.
    Jonsson, Tomas
    University of Skövde, The Systems Biology Research Centre. University of Skövde, School of Life Sciences.
    Emmerson, Mark C.
    Temporal Variability in Predator - Prey Relationships of a Forest Floor Food Web2010In: Advances in Ecological Research, ISSN 0065-2504, E-ISSN 2163-582X, Vol. 42, p. 171-264Article in journal (Refereed)
    Abstract [en]

    Connectance webs represent the standard data description in food web ecology, but their usefulness is often limited in understanding the patterns and processes within ecosystems. Increasingly, efforts have been made to incorporate additional, biologically meaningful, data into food web descriptions, including the construction of food webs using data describing the body size and abundance of each species. Here, data from a terrestrial forest floor food web, sampled seasonally over a 1-year period, were analysed to investigate (i) how stable the body size–abundance and predator–prey relationships of an ecosystem are through time and (ii) whether there are system-specific differences in body size–abundance and predator–prey relationships between ecosystem types.

  • 32.
    Neubert, Michael G.
    et al.
    Biology Department, Woods Hole Oceanographic Institution, Woods Hole, MA, United States.
    Blumenshine, Steven C.
    Department of Biological Sciences, Arkansas State University, State University, United States.
    Duplisea, Daniel E.
    CEFAS Lowestoft Laboratory, Lowestoft, Suffolk, United Kingdom.
    Jonsson, Tomas
    Department of Biology, Linköping University, Linköping, Sweden / Rockefeller University, New York, NY, United States.
    Rashleigh, Brenda
    EPA Ecosystems Assessment Branch, Athens, GA, United States.
    Body size and food web structure: testing the equiprobability assumption of the cascade model2000In: Oecologia, ISSN 0029-8549, E-ISSN 1432-1939, Vol. 123, no 2, p. 241-251Article in journal (Refereed)
  • 33.
    Nyberg, Per
    et al.
    Fiskeriverkets Sötvattenslaboratorium (nuvarande Institutionen för akvatiska resurser, SLU).
    Degerman, Erik
    Fiskeriverkets Sötvattenslaboratorium (nuvarande Institutionen för akvatiska resurser, SLU).
    Setzer, Malin
    University of Skövde, School of Life Sciences. University of Skövde, The Systems Biology Research Centre.
    Norrgård, Johnny
    Vätternvårdsförbundet.
    Jonsson, Tomas
    University of Skövde, School of Life Sciences. University of Skövde, The Systems Biology Research Centre. School of Bioscience, University of Skövde.
    Predation av fisk och signalkräfta på rödingrom - resultat från en fältstudie i Vättern2012Report (Other academic)
    Abstract [sv]

    Vätterns unika bestånd av storröding har minskat kraftigt de senaste decennierna och orsakerna till minskningen diskuteras livligt. Bland föreslagna orsaker nämns exvis konkurrens från inplanterad lax, överexploatering och klimatförändringar. Därutöver befaras även signalkräftan, via predation på rödingrom kunna ha en negativ inverkan på rödingens reproduktion. För att undersöka predationen på rödingrom från såväl fisk som signalkräfta utfördes 2009 ett fältförsök vid en känd lekplats i norra Vättern. I de använda försöksburarna var den uppskattade mortaliteten av ägg till följd av kräftpredation 5 gånger högre än den till följd av fiskpredation. Resultaten indikerar därmed att predationen på rödingrom från signalkräfta kan vara kraftigt underskattad och att den kan ha påverkat rödingbeståndets återhämtning i Vättern negativt.

  • 34.
    O'Gorman, Eoin J.
    et al.
    University College Cork.
    Jacob, Ute
    University College Cork.
    Jonsson, Tomas
    University of Skövde, The Systems Biology Research Centre. University of Skövde, School of Life Sciences.
    Emmerson, Mark C.
    University College Cork.
    Interaction strength, food web topology and the relative importance of species in food webs.2010In: Journal of Animal Ecology, ISSN 0021-8790, E-ISSN 1365-2656, Vol. 79, no 3, p. 682-692Article in journal (Refereed)
    Abstract [en]

    1. We established complex marine communities, consisting of over 100 species, in large subtidal experimental mesocosms. We measured the strength of direct interactions and the net strength of direct and indirect interactions between the species in those communities, using a combination of theoretical and empirical approaches.

    2. Theoretical predictions of interaction strength were derived from the interaction coefficient matrix, which was parameterised using allometric predator–prey relationships. Empirical estimates of interaction strength were quantified using the ln-ratio, which measures the change in biomass density of species A in the presence and absence of species B.

    3. We observed that highly connected species tend to have weak direct effects and net effects in our experimental food webs, whether we calculate interaction strength theoretically or empirically.

    4. We found a significant correlation between our theoretical predictions and empirical estimates of direct effects and net effects. The net effects correlation was much stronger, indicating that our experimental communities were dominated by a mixture of direct and indirect effects.

    5. Re-calculation of the theoretical predictions of net effects after randomising predator and prey body masses did not affect the negative relationship with connectance.

    6. These results suggest that food web topology, which in this system is constrained by body mass, is overwhelmingly important for the magnitude of direct and indirect interactions and hence species importance in the face of biodiversity declines.

  • 35.
    Riede, Jens O.
    et al.
    J.F. Blumenbach Institute of Zoology and Anthropology, Systemic Conservation Biology Group, Georg-August University Goettingen, 37073 Goettingen, Germany.
    Brose, Ulrich
    J.F. Blumenbach Institute of Zoology and Anthropology, Systemic Conservation Biology Group, Georg-August University Goettingen, 37073 Goettingen, Germany.
    Ebenman, Bo
    IFM Theory and Modelling, Division of Theoretical Biology, Linköping University, S-581 83 Linköping, Sweden.
    Jacob, Ute
    Institute for Hydrobiology and Fisheries Science, University Hamburg, 22767 Hamburg, Germany.
    Thompson, Ross
    School of Biological Sciences, Monash University, Bld 18, Vic. 3800, Australia.
    Townsend, Colin R.
    Department of Zoology, University of Otago, Dunedin 9054, New Zealand.
    Jonsson, Tomas
    University of Skövde, School of Life Sciences. University of Skövde, The Systems Biology Research Centre.
    Stepping in Elton's footprints: a general scaling model for body masses and trophic levels across ecosystems2011In: Ecology Letters, ISSN 1461-023X, E-ISSN 1461-0248, Vol. 14, no 2, p. 169-178Article in journal (Refereed)
    Abstract [en]

    Despite growing awareness of the significance of body-size and predator–prey body-mass ratios for the stability of ecological networks, our understanding of their distribution within ecosystems is incomplete. Here, we study the relationships between predator and prey size, body-mass ratios and predator trophic levels using body-mass estimates of 1313 predators (invertebrates, ectotherm and endotherm vertebrates) from 35 food-webs (marine, stream, lake and terrestrial). Across all ecosystem and predator types, except for streams (which appear to have a different size structure in their predator–prey interactions), we find that (1) geometric mean prey mass increases with predator mass with a power-law exponent greater than unity and (2) predator size increases with trophic level. Consistent with our theoretical derivations, we show that the quantitative nature of these relationships implies systematic decreases in predator–prey body-mass ratios with the trophic level of the predator. Thus, predators are, on an average, more similar in size to their prey at the top of food-webs than that closer to the base. These findings contradict the traditional Eltonian paradigm and have implications for our understanding of body-mass constraints on food-web topology, community dynamics and stability.

  • 36.
    Roubinet, Eve
    et al.
    Department of Ecology, Swedish University of Agricultural Sciences, Uppsala, Sweden.
    Jonsson, Tomas
    University of Skövde, School of Bioscience. University of Skövde, The Systems Biology Research Centre. Department of Ecology, Swedish University of Agricultural Sciences, Uppsala, Sweden.
    Malsher, Gerard
    Department of Ecology, Swedish University of Agricultural Sciences, Uppsala, Sweden.
    Staudacher, Karin
    Mountain Agriculture Research Unit, Institute of Ecology, University of Innsbruck, Innsbruck, Austria.
    Traugott, Michael
    Mountain Agriculture Research Unit, Institute of Ecology, University of Innsbruck, Innsbruck, Austria.
    Ekbom, Barbara
    Department of Ecology, Swedish University of Agricultural Sciences, Uppsala, Sweden.
    Jonsson, Mattias
    Department of Ecology, Swedish University of Agricultural Sciences, Uppsala, Sweden.
    High Redundancy as well as Complementary Prey Choice Characterize Generalist Predator Food Webs in Agroecosystems2018In: Scientific Reports, ISSN 2045-2322, E-ISSN 2045-2322, Vol. 8, article id 8054Article in journal (Refereed)
    Abstract [en]

    Food web structure influences ecosystem functioning and the strength and stability of associated ecosystem services. With their broad diet, generalist predators represent key nodes in the structure of many food webs and they contribute substantially to ecosystem services such as biological pest control. However, until recently it has been difficult to empirically assess food web structure with generalist predators. We utilized DNA-based molecular gut-content analyses to assess the prey use of a set of generalist invertebrate predator species common in temperate agricultural fields. We investigated the degree of specialization of predator-prey food webs at two key stages of the cropping season and analysed the link temperature of different trophic links, to identify non-random predation. We found a low level of specialization in our food webs, and identified warm and cool links which may result from active prey choice or avoidance. We also found a within-season variation in interaction strength between predators and aphid pests which differed among predator species. Our results show a high time-specific functional redundancy of the predator community, but also suggest temporally complementary prey choice due to within-season succession of some predator species.

  • 37.
    Roubinet, Eve
    et al.
    Department of Ecology, Swedish University of Agricultural Sciences, Uppsala, Sweden.
    Straub, Cory
    Biology Department, Ursinus College, Collegeville, Pennsylvania, U.S.A.
    Jonsson, Tomas
    Department of Ecology, Swedish University of Agricultural Sciences, Uppsala, Sweden.
    Staudacher, Karin
    Mountain Agriculture Research Unit, Institute of Ecology, University of Innsbruck, Innsbruck, Austria.
    Traugott, Michael
    Mountain Agriculture Research Unit, Institute of Ecology, University of Innsbruck, Innsbruck, Austria.
    Ekbom, Barbara
    Department of Ecology, Swedish University of Agricultural Sciences, Uppsala, Sweden.
    Jonsson, Mattias
    Department of Ecology, Swedish University of Agricultural Sciences, Uppsala, Sweden.
    Additive effects of predator diversity on pest control caused by few interactions among predator species2015In: Ecological Entomology, ISSN 0307-6946, E-ISSN 1365-2311, Vol. 40, no 4, p. 362-371Article in journal (Refereed)
  • 38.
    Setzer, Malin
    et al.
    University of Skövde, School of Life Sciences. University of Skövde, The Systems Biology Research Centre.
    Norrgård, Johnny R.
    Management and Ecology of River Resources, Department of Biology, Karlstad University, Karlstad, Sweden.
    Jonsson, Tomas
    University of Skövde, School of Life Sciences. University of Skövde, The Systems Biology Research Centre.
    An invasive crayfish affects egg survival and the potential recovery of an endangered population of Arctic charr2011In: Freshwater Biology, ISSN 0046-5070, E-ISSN 1365-2427, Vol. 56, no 12, p. 2543-2553Article in journal (Refereed)
    Abstract [en]

    Summary

    1. Many fish stocks have declined, because of overharvesting, habitat destruction and introduced species. Despite efforts to rehabilitate some of these stocks, not all are responding or are recovering only slowly.

    2. In freshwater systems, introduced crayfish are often problematic, and it has been suggested that their egg predation could reduce recruitment in depleted stocks of native fish.

    3. Here, we report the results of a field experiment, using experimental cages, on the extent of predation on eggs of great Arctic charr (Salvelinus umbla) in Lake Vättern, Europe’s fifth largest lake. Here, the great Arctic charr has declined dramatically and is listed as critically endangered.

    4. We were able to partition the total loss rate of eggs into background mortality, predation by introduced signal crayfish (Pacifastacus leniusculus) and predation by native fish. The mortality rate of charr eggs because of crayfish was estimated at more than five times that because of native fish. Of the total loss of eggs, 80% is believed to be caused by crayfish and 14% by fish, with 6% being natural background mortality.

    5. In a worst case scenario, our data infer that only 25% of the original number of eggs would survive, compared with 75% in the absence of crayfish. This could impair recovery of the stock of the endangered great Arctic charr in Lake Vättern.

    6. Contrary to earlier claims that crayfish predation on eggs of great Arctic charr is insignificant, our results indicate that crayfish predation may exceed fish predation and suggest that the abundance of signal crayfish on the spawning sites of great Arctic charr should be managed.

  • 39.
    Säterberg, Torbjörn
    et al.
    Linköping University, Department of Physics, Chemistry and Biology, Division of Theoretical Biology, Sweden / Swedish University of Agricultural Sciences, Department of Aquatic Resources, Öregrund, Sweden.
    Jonsson, Tomas
    University of Skövde, School of Bioscience. University of Skövde, The Systems Biology Research Centre. Swedish University of Agricultural Sciences, Department of Ecology, Uppsala, Sweden.
    Yearsley, Jon
    University College Dublin, School of Biology & Environmental Science, Ireland / UCD Earth Institute, Belfield, Dublin 4, Ireland.
    Berg, Sofia
    University of Skövde, School of Bioscience. University of Skövde, The Systems Biology Research Centre.
    Ebenman, Bo
    Linköping University, Department of Physics, Chemistry and Biology, Division of Theoretical Biology, Sweden / Stockholm University, SRC, Sweden.
    A potential role for rare species in ecosystem dynamics2019In: Scientific Reports, ISSN 2045-2322, E-ISSN 2045-2322, Vol. 9, p. 1-12, article id 11107Article in journal (Refereed)
    Abstract [en]

    The ecological importance of common species for many ecosystem processes and functions is unquestionably due to their high a bundance.Yet, the importance of rare species is much less understood. Here we take a theoretical approach, exposing dynamical models of ecological networks to small perturbations, to explore the dynamical importance of rare and common species. We find that both species types contribute to the recovery of communities following generic perturbations (i.e. perturbations affecting all species).Yet, when perturbations are selective (i.e. affects only one species), perturbations to rare species have the most pronounced effect on community stability. We show that this is due to the strong indirect effects induced by perturbations to rare species. Because indirect effects typically set in at longer timescales, our results indicate that the importance of rare species may be easily overlooked and thus underrated. Hence, our study provides a potential ecological motive for the management and protection of rare species.

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