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  • 1.
    Cirtwill, Alyssa
    et al.
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Teoretisk Biologi. Linköpings universitet, Tekniska fakulteten. Stockholm Univ, Sweden.
    Eklöf, Anna
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Teoretisk Biologi. Linköpings universitet, Tekniska fakulteten.
    Roslin, Tomas
    Swedish Univ Agr Sci, Sweden.
    Wootton, Kate
    Swedish Univ Agr Sci, Sweden.
    Gravel, Dominique
    Univ Sherbrooke, Canada.
    A quantitative framework for investigating the reliability of empirical network construction2019Ingår i: Methods in Ecology and Evolution, ISSN 2041-210X, E-ISSN 2041-210X, Vol. 10, nr 6, s. 902-911Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Descriptions of ecological networks typically assume that the same interspecific interactions occur each time a community is observed. This contrasts with the known stochasticity of ecological communities: community composition, species abundances and link structure all vary in space and time. Moreover, finite sampling generates variation in the set of interactions actually observed. For interactions that have not been observed, most datasets will not contain enough information for the ecologist to be confident that unobserved interactions truly did not occur. Here, we develop the conceptual and analytical tools needed to capture uncertainty in the estimation of pairwise interactions. To define the problem, we identify the different contributions to the uncertainty of an interaction. We then outline a framework to quantify the uncertainty around each interaction by combining data on observed co-occurrences with prior knowledge. We illustrate this framework using perhaps the most extensively sampled network to date. We found significant uncertainty in estimates for the probability of most pairwise interactions. This uncertainty can, however, be constrained with informative priors. This uncertainty scaled up to summary measures of network structure such as connectance and nestedness. Even with informative priors, we are likely to miss many interactions that may occur rarely or under different local conditions. Overall, we demonstrate the importance of acknowledging the uncertainty inherent in network studies, and the utility of treating interactions as probabilities in pinpointing areas where more study is needed. Most importantly, we stress that networks are best thought of as systems constructed from random variables, the stochastic nature of which must be acknowledged for an accurate representation. Doing so will fundamentally change network analyses and yield greater realism.

  • 2.
    Årevall, Jonatan
    et al.
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Teoretisk Biologi. Linköpings universitet, Tekniska fakulteten.
    Early, Regan
    Univ Exeter Penryn Campus, England.
    Estrada, Alba
    Oviedo Univ Campus Mieres, Spain.
    Wennergren, Uno
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Teoretisk Biologi. Linköpings universitet, Tekniska fakulteten.
    Eklöf, Anna
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Teoretisk Biologi. Linköpings universitet, Tekniska fakulteten.
    Conditions for successful range shifts under climate change: The role of species dispersal and landscape configuration2018Ingår i: Diversity & distributions: A journal of biological invasions and biodiversity, ISSN 1366-9516, E-ISSN 1472-4642, Vol. 24, nr 11, s. 1598-1611Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Aim: Ongoing climate change is currently modifying the geographical location of areas that are climatically suitable for species. Understanding a species ability to successfully shift its geographical range would allow us to assess extinction risks and predict future community compositions. We investigate how habitat configuration impedes or promotes climate-driven range shifts, given different speeds of climate change and dispersal abilities. Location: Theoretical, but illustrated with European examples. Methods: We model how a species ability to track a directional shift in climatic conditions is affected by (a) species dispersal abilities; (b) speed of climatic shift; and (c) spatial arrangement of the habitat. Our modelling framework includes within-and between-patch population dynamics and uses ecologically realistic habitat distributions and dispersal scenarios (verified with data from a set of European mammal species) and, as such, is an improvement of classical range shift models. Result: In landscapes with a homogeneous distribution of suitable habitats, all but the least dispersive species will be able to range shift. However, species with high dispersal ability will have lower population densities after range shift. In heterogeneous landscapes species ability to range shift is far more variable and heavily dependent on the habitat configuration. This means that landscape configuration in combination with the speed of climate change and species dispersal abilities give rise to nonlinear effects on population sizes and survival after a climatic shift. Main conclusions: Our analyses point out the importance of accounting for the interplay of species dispersal and the landscape configuration when estimating future climate impact on species. These results link ecologically important attributes of both species and their landscapes to outcomes of species range shift, and thereby long-term persistence of ecological communities.

  • 3.
    Cirtwill, Alyssa
    et al.
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Teoretisk Biologi. Linköpings universitet, Tekniska fakulteten.
    Eklöf, Anna
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Teoretisk Biologi. Linköpings universitet, Tekniska fakulteten.
    Feeding environment and other traits shape species roles in marine food webs2018Ingår i: Ecology Letters, ISSN 1461-023X, E-ISSN 1461-0248, Vol. 21, nr 6, s. 875-884Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Food webs and meso-scale motifs allow us to understand the structure of ecological communities and define species roles within them. This species-level perspective on networks permits tests for relationships between species traits and their patterns of direct and indirect interactions. Such relationships could allow us to predict food-web structure based on more easily obtained trait information. Here, we calculated the roles of species (as vectors of motif position frequencies) in six well-resolved marine food webs and identified the motif positions associated with the greatest variation in species roles. We then tested whether the frequencies of these positions varied with species traits. Despite the coarse-grained traits we used, our approach identified several strong associations between traits and motifs. Feeding environment was a key trait in our models and may shape species roles by affecting encounter probabilities. Incorporating environment into future food-web models may improve predictions of an unknown network structure.

  • 4.
    Dee, Laura E.
    et al.
    University of Minnesota Twin Cities, MN 55108 USA; University of Minnesota Twin Cities, MN 55108 USA.
    Allesina, Stefano
    University of Chicago, IL 60637 USA; University of Chicago, IL 60637 USA.
    Bonn, Aletta
    UFZ Helmholtz Centre Environm Research, Germany; Friedrich Schiller University of Jena, Germany; Gerrnan Centre Integrat Biodivers Research iDiv, Germany.
    Eklöf, Anna
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Teoretisk Biologi. Linköpings universitet, Tekniska fakulteten.
    Gaines, Steven D.
    University of Calif Santa Barbara, CA 93117 USA.
    Hines, Jes
    Gerrnan Centre Integrat Biodivers Research iDiv, Germany; University of Leipzig, Germany.
    Jacob, Ute
    Gerrnan Centre Integrat Biodivers Research iDiv, Germany; University of Goettingen, Germany.
    McDonald-Madden, Eve
    University of Queensland, Australia.
    Possingham, Hugh
    University of Queensland, Australia.
    Schroeter, Matthias
    UFZ Helmholtz Centre Environm Research, Germany; Gerrnan Centre Integrat Biodivers Research iDiv, Germany.
    Thompson, Ross M.
    University of Canberra, Australia.
    Operationalizing Network Theory for Ecosystem Service Assessments2017Ingår i: Trends in Ecology & Evolution, ISSN 0169-5347, E-ISSN 1872-8383, Vol. 32, nr 2, s. 118-130Artikel, forskningsöversikt (Refereegranskat)
    Abstract [en]

    Managing ecosystems to provide ecosystem services in the face of global change is a pressing challenge for policy and science. Predicting how alternative management actions and changing future conditions will alter services is complicated by interactions among components in ecological and socioeconomic systems. Failure to understand those interactions can lead to detrimental outcomes from management decisions. Network theory that integrates ecological and socioeconomic systems may provide a path to meeting this challenge. While network theory offers promising approaches to examine ecosystem services, few studies have identified how to operationalize networks for managing and assessing diverse ecosystem services. We propose a framework for how to use networks to assess how drivers and management actions will directly and indirectly alter ecosystem services.

  • 5.
    Brose, Ulrich
    et al.
    German Centre for Integrative Biodiversity Research (iDiv) Halle-Jena-Leipzig, 04103, Leipzig, Germany 2 Faculty of Biology and Pharmacy, Institute of Ecology, Friedrich Schiller University Jena, 07743, Jena, Germany.
    Blanchard, Julia L.
    Institute for Marine and Antarctic Studies and Centre for Marine Socioecology, University of Tasmania, 20 Castray Esplanade, Battery Point TAS 7004 Australia.
    Eklöf, Anna
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Teoretisk Biologi. Linköpings universitet, Tekniska fakulteten.
    Galiana, Nuria
    Ecological Networks and Global Change Group, Experimental Ecology Station, Centre National de la Recherche Scientifique, 09200, Moulis, France.
    Hartvig, Martin
    Center for Macroecology, Evolution and Climate, Natural History Museum of Denmark, University of Copenhagen, DK-2100, Copenhagen, Denmark 7 National Institute of Aquatic Resources, Technical University of Denmark, DK-2920, Charlottenlund, Denmark 8 Systemic Conservation Biology Group, J.F. Blumenbach Institute of Zoology and Anthropology, Georg-August University of Göttingen, 37073, Göttingen, Germany.
    Hirt, Myriam R.
    German Centre for Integrative Biodiversity Research (iDiv) Halle-Jena-Leipzig, 04103, Leipzig, Germany 2 Faculty of Biology and Pharmacy, Institute of Ecology, Friedrich Schiller University Jena, 07743, Jena, Germany.
    Kalinkat, Gregor
    Department of Biology and Ecology of Fishes, Leibniz-Institute of Freshwater Ecology and Inland Fisheries, 12587, Berlin, Germany 10 Department of Fish Ecology and Evolution, Eawag, 6047, Kastanienbaum, Switzerland.
    Nordström, MArie C.
    Environmental and Marine Biology, Åbo Akademi University, FI-20520, Åbo, Finland.
    O'Gorman, Eoin J.
    Imperial College London, Silwood Park Campus, Buckhurst Road, Ascot, Berkshire, SL5 7PY, UK.
    Rall, Björn C.
    German Centre for Integrative Biodiversity Research (iDiv) Halle-Jena-Leipzig, 04103, Leipzig, Germany 2 Faculty of Biology and Pharmacy, Institute of Ecology, Friedrich Schiller University Jena, 07743, Jena, Germany.
    Schneider, Florian D.
    Institut des Sciences de l’Evolution, Universit´e Montpellier, CNRS, IRD, EPHE, CC065, 34095, Montpellier Cedex 05, France.
    Thébault, Elisa
    Institute of Ecology and Environmental Sciences - Paris, UMR 7618 (UPMC, CNRS, IRD, INRA, UPEC, Paris Diderot), Universit´e Pierre et Marie Curie, 75005, Paris, France.
    Jacob, Ute
    Department of Biology, Institute for Hydrobiology and Fisheries Science, Center for Earth System Research and Sustainability (CEN), KlimaCampus, University of Hamburg, 22767, Hamburg, Germany.
    Predicting the consequences of species lossusing size-structured biodiversity approaches2017Ingår i: Biological Reviews, ISSN 1464-7931, E-ISSN 1469-185X, Vol. 92, nr 2, s. 684-697Artikel, forskningsöversikt (Refereegranskat)
    Abstract [en]

    Understanding the consequences of species loss in complex ecological communities is one of the great challenges in current biodiversity research. For a long time, this topic has been addressed by traditional biodiversity experiments. Most of these approaches treat species as trait-free, taxonomic units characterizing communities only by species number without accounting for species traits. However, extinctions do not occur at random as there is a clear correlation between extinction risk and species traits. In this review, we assume that large species will be most threatened by extinction and use novel allometric and size-spectrum concepts that include body mass as a primary species trait at the levels of populations and individuals, respectively, to re-assess three classic debates on the relationships between biodiversity and (i) food-web structural complexity, (ii) community dynamic stability, and (iii) ecosystem functioning. Contrasting current expectations, size-structured approaches suggest that the loss of large species, that typically exploit most resource species, may lead to future food webs that are less interwoven and more structured by chains of interactions and compartments. The disruption of natural body-mass distributions maintaining food-web stability may trigger avalanches of secondary extinctions and strong trophic cascades with expected knock-on effects on the functionality of the ecosystems. Therefore, we argue that it is crucial to take into account body size as a species trait when analysing the consequences of biodiversity loss for natural ecosystems. Applying size-structured approaches provides an integrative ecological concept that enables a better understanding of each species' unique role across communities and the causes and consequences of biodiversity loss.

  • 6.
    Eklöf, Anna
    et al.
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Teoretisk Biologi. Linköpings universitet, Tekniska fakulteten.
    Stouffer, Daniel B.
    Centre for Integrative Ecology, School of Biological Sciences, University of Canterbury, Christchurch 8140, New Zealan.
    The phylogenetic component of food web structure and intervality2016Ingår i: Theoretical Ecology, ISSN 1874-1738, E-ISSN 1874-1746, Vol. 9, nr 1, s. 107-115Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Despite the exceptional complexity formed byspecies and their interactions in ecological networks, such asfood webs, regularities in the network structures are repeat-edly demonstrated. The interactions are determined by thecharacteristics of a species. The characteristics are in turndetermined by the species’ phylogenetic relationships, butalso by factors not related to evolutionary history. Here, wetest whether species’ phylogenetic relationships provides asignificant proxy for food web intervality. We thereafterquantify the degree to which different species traits remainvaluable predictors of food web structure after the base-line effect of species’ relatedness has been removed. Wefind that the phylogenetic relationships provide a significantbackground from which to estimate food web intervalityand thereby structure. However, we also find that thereis an important, non-negligible part of some traits, e.g.,body size, in food webs that is not accounted for by thephylogenetic relationships. Additionally, both these rela-tionships differ depending if a predator or a prey perspectiveis adopted. Clearly, species’ evolutionary history as well astraits not determined by phylogenetic relationships shapes predator-prey interactions in food webs, and the underly-ing evolutionary processes take place on slightly differenttime scales depending on the direction of predator-preyadaptations.

  • 7.
    Gudmundson, Sara
    et al.
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Teoretisk Biologi. Linköpings universitet, Tekniska fakulteten.
    Eklöf, Anna
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Teoretisk Biologi. Linköpings universitet, Tekniska fakulteten.
    Wennergren, Uno
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Teoretisk Biologi. Linköpings universitet, Tekniska fakulteten.
    Environmental variability uncovers disruptive effects of species interactions on population dynamics2015Ingår i: Proceedings of the Royal Society of London. Biological Sciences, ISSN 0962-8452, E-ISSN 1471-2954, Vol. 282, nr 1812, s. 67-75Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    How species respond to changes in environmental variability has been shown for single species, but the question remains whether these results are transferable to species when incorporated in ecological communities. Here, we address this issue by analysing the same species exposed to a range of environmental variabilities when (i) isolated or (ii) embedded in a food web. We find that all species in food webs exposed to temporally uncorrelated environments (white noise) show the same type of dynamics as isolated species, whereas species in food webs exposed to positively autocorrelated environments (red noise) can respond completely differently compared with isolated species. This is owing to species following their equilibrium densities in a positively autocorrelated environment that in turn enables species species interactions to come into play. Our results give new insights into species response to environmental variation. They especially highlight the importance of considering both species interactions and environmental autocorrelation when studying population dynamics in a fluctuating environment.

  • 8.
    Jacob, Ute
    et al.
    Institute of Hydrobiology and Fisheries Science, University of Hamburg, Germany.
    Jonsson, Tomas
    Pupulation 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
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Teoretisk Biologi. Linköpings universitet, Tekniska fakulteten.
    Mintenbeck, Katja
    Alfred Wegener Institute for Polar and Marine Research, Bremerhaven, Germany.
    Möllmann, Christian
    Institute of Hydrobiology and Fisheries Science, University of Hamburg, Germany.
    Morisette, 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, Switzerland.
    Valuing biodiversity and ecosystem services in a complex marine ecosystem2015Ingår i: Aquatic functional biodiversity: an ecological and evolutionary perspective / [ed] Andrea Belgrano, Guy Woodward, Ute Jacob, London: Academic Press, 2015, 1, s. 189-207Kapitel i bok, del av antologi (Refereegranskat)
  • 9.
    Edstam, Monika M.
    et al.
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Biologi. Linköpings universitet, Tekniska högskolan.
    Blomqvist, Kristina
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Biologi. Linköpings universitet, Tekniska högskolan.
    Eklöf, Anna
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Teoretisk Biologi. Linköpings universitet, Tekniska högskolan.
    Wennergren, Uno
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Teoretisk Biologi. Linköpings universitet, Tekniska högskolan.
    Edqvist, Johan
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Biologi. Linköpings universitet, Tekniska högskolan.
    Coexpression patterns indicate that GPI-anchored non-specific lipid transfer proteins are involved in accumulation of cuticular wax, suberin and sporopollenin2013Ingår i: Plant Molecular Biology, ISSN 0167-4412, E-ISSN 1573-5028, Vol. 83, nr 6, s. 625-649Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The non-specific lipid transfer proteins (nsLTP) are unique to land plants. The nsLTPs are characterized by a compact structure with a central hydrophobic cavity and can be classified to different types based on sequence similarity, intron position or spacing between the cysteine residues. The type G nsLTPs (LTPGs) have a GPI-anchor in the C-terminal region which attaches the protein to the exterior side of the plasma membrane. The function of these proteins, which are encoded by large gene families, has not been systematically investigated so far. In this study we have explored microarray data to investigate the expression pattern of the LTPGs in Arabidopsis and rice. We identified that the LTPG genes in each plant can be arranged in three expression modules with significant coexpression within the modules. According to expression patterns and module sizes, the Arabidopsis module AtI is functionally equivalent to the rice module OsI, AtII corresponds to OsII and AtIII is functionally comparable to OsIII. Starting from modules AtI, AtII and AtIII we generated extended networks with Arabidopsis genes coexpressed with the modules. Gene ontology analyses of the obtained networks suggest roles for LTPGs in the synthesis or deposition of cuticular waxes, suberin and sporopollenin. The AtI-module is primarily involved with cuticular wax, the AtII-module with suberin and the AtIII-module with sporopollenin. Further transcript analysis revealed that several transcript forms exist for several of the LTPG genes in both Arabidopsis and rice. The data suggests that the GPI-anchor attachment and localization of LTPGs may be controlled to some extent by alternative splicing.

  • 10.
    Eklöf, Anna
    et al.
    Department of Ecology & Evolution, University of Chicago, Chicago, IL, USA; and.
    Tang, Si
    Department of Ecology & Evolution, University of Chicago, Chicago, IL, USA; and.
    Allesina, Stefano
    Department of Ecology & Evolution, University of Chicago, Chicago, IL, USA; and Computatio n Institute, University of Chicago, Chicago, IL, USA.
    Secondary extinctions in food webs: a Bayesian network approach2013Ingår i: Methods in Ecology and Evolution, ISSN 2041-210X, E-ISSN 2041-210X, Vol. 4, nr 8, s. 760-770Artikel i tidskrift (Refereegranskat)
    Abstract [en]
    1. Ecological communities are composed of populations connected in tangled networks of ecological interactions. Therefore, the extinction of a species can reverberate through the network and cause other (possibly distantly connected) species to go extinct as well. The study of these secondary extinctions is a fertile area of research in ecological network theory.
    2. However, to facilitate practical applications, several improvements to the current analytical approaches are needed. In particular, we need to consider that (i) species have different ‘a priori’ probabilities of extinction, (ii) disturbances can simultaneously affect several species, and (iii) extinction risk of consumers likely grows with resource loss. All these points can be included in dynamical models, which are, however, difficult to parameterize.
    3. Here we advance the study of secondary extinctions with Bayesian networks. We show how this approach can account for different extinction responses using binary – where each resource has the same importance – and quantitative data – where resources are weighted by their importance. We simulate ecological networks using a popular dynamical model (the Allometric Trophic Network model) and use it to test our method.
    4. We find that the Bayesian network model captures the majority of the secondary extinctions produced by the dynamical model and that consumers’ responses to species loss are best modelled using a nonlinear sigmoid function. We also show that an approach based exclusively on food web structure loses power when species at higher trophic levels are preferentially lost. Because the loss of apex predators is unfortunately widespread, the results highlight a serious limitation of studies on network robustness.
  • 11.
    Eklöf, Anna
    et al.
    Department of Ecology & Evolution, University of Chicago, Chicago, IL,USA.
    Jacob, Ute
    Institute for Hydrobiology and Fisheries Science, Hamburg, Germany.
    Kopp, Jason
    Department of Ecology & Evolution, University of Chicago, Chicago, IL,USA.
    Bosch, Jordi
    CREAF – Ecology Unit, Universitat Autonoma de Barcelona, Barcelona, Spain.
    Castro-Urgal, Rocio
    Institut Mediterrani d’Estudis Avanc¸ats (CSIC-UIB), Mallorca, Balearic Islands, Spain.
    Chacoff, Natacha P.
    Instituto Argentino de Investigaciones de las Zonas Aridas, CONICET, Mendoza, Argentina.
    Dalsgaard, Bo
    Center for Macroecology, Evolution and Climate, Department of Biology, University of Copenhagen, Copenhagen, Denmark.
    de Sassi, Claudio
    School of Biological Sciences, University of Canterbury, Canterbury, New Zealand.
    Galetti, Mauro
    Departamento de Ecologia, Universidade Estadual Paulista, Rio Claro, Brazil.
    Guimaraes, Paulo R.
    Departamento de Ecologia, I.B, Universidade de S~ao Paulo, Sao Paulo, Brazil.
    Lomascolo, Silvia Beatriz
    Instituto Argentino de Investigaciones de las Zonas Aridas, CONICET, Mendoza, Argentina, Instituto de Ciencias Basicas, Universidad Nacional de Cuyo, Mendoza, Argentina .
    Martin Gonzales, Ana M.
    Center for Macroecology, Evolution and Climate, Department of Biology, University of Copenhagen, Copenhagen, Denmark, Pacific Ecoinformatics and Computational Ecology Lab, Berkeley, CA, USA .
    Pizo, Marco Aurelio
    Departamento de Zoologia, Universidade Estadual Paulista, S~ao Paulo, Brazil.
    Rader, Romina
    Department of Physical Geography and Quaternary Geology, Stockholm University, Stockholm, Sweden.
    Rodrigo, Anselm
    CREAF – Ecology Unit, Universitat Autonoma de Barcelona, Barcelona, Spain.
    Tylianakis, Jason M.
    School of Biological Sciences, University of Canterbury, Canterbury, New Zealand.
    Vásquez, Diego P.
    Instituto Argentino de Investigaciones de las Zonas Aridas, CONICET, Mendoza, Argentina, Instituto de Ciencias Basicas, Universidad Nacional de Cuyo, Mendoza, Argentina.
    Allesina, Stefano
    Department of Ecology & Evolution, University of Chicago, Chicago, IL,USA, Computation Institute, University of Chicago, Chicago, USA .
    The dimensionality of ecological networks2013Ingår i: Ecology Letters, ISSN 1461-023X, E-ISSN 1461-0248, Vol. 16, nr 5, s. 577-583Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    How many dimensions (trait-axes) are required to predict whether two species interact? This unansweredquestion originated with the idea of ecological niches, and yet bears relevance today for understanding whatdetermines network structure. Here, we analyse a set of 200 ecological networks, including food webs,antagonistic and mutualistic networks, and find that the number of dimensions needed to completelyexplain all interactions is small ( < 10), with model selection favouring less than five. Using 18 high-qualitywebs including several species traits, we identify which traits contribute the most to explaining networkstructure. We show that accounting for a few traits dramatically improves our understanding of the structureof ecological networks. Matching traits for resources and consumers, for example, fruit size and billgape, are the most successful combinations. These results link ecologically important species attributes tolarge-scale community structure.

  • 12.
    Eklöf, Anna
    et al.
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Teoretisk Biologi. Linköpings universitet, Tekniska högskolan.
    Kaneryd, Linda
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Teoretisk Biologi. Linköpings universitet, Tekniska högskolan.
    Münger, Peter
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Teoretisk Fysik. Linköpings universitet, Tekniska högskolan.
    Climate change in metacommunities: dispersal gives double-sided effects on persistence2012Ingår i: Philosphical Transactions of the Royal Society B, ISSN 1471-2970, Vol. 367, nr 1605, s. 2945-2954Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Climate change is increasingly affecting the structure and dynamics of ecological communities bothat local and at regional scales, and this can be expected to have important consequences for theirrobustness and long-term persistence. The aim of the present work is to analyse how the spatialstructure of the landscape and dispersal patterns of species (dispersal rate and average dispersal distance)affects metacommunity response to two disturbances: (i) increased mortality during dispersaland (ii) local species extinction. We analyse the disturbances both in isolation and in combination.Using a spatially and dynamically explicit metacommunity model, we find that the effect of dispersalon metacommunity persistence is two-sided: on the one hand, high dispersal significantly reducesthe risk of bottom-up extinction cascades following the local removal of a species; on the otherhand, when dispersal imposes a risk to the dispersing individuals, high dispersal increases extinctionrisks, especially when dispersal is global. Large-bodied species with long generation times at thehighest trophic level are particularly vulnerable to extinction when dispersal involves a risk. Thissuggests that decreasing the mortality risk of dispersing individuals by improving the quality ofthe habitat matrix may greatly increase the robustness of metacommunities.

  • 13.
    Eklöf, Anna
    et al.
    University of Chicago, Illinois, USA.
    Allesina, Stefano
    University of Chicago, Illinois, USA.
    Networks, Ecological2012Ingår i: Encyclopedia of Theoretical Ecology / [ed] Alan Hastings, Louis Gross, University of California Press, 2012, 1, s. 470-478Kapitel i bok, del av antologi (Refereegranskat)
  • 14.
    Eklöf, Anna
    et al.
    Department of Ecology and Evolution, University of Chicago, Chicago, IL 60637, USA.
    Helmus, Matthew R.
    Department of Ecology and Evolution, University of Chicago, Chicago, IL 60637, USA.
    Moore, M.
    Department of Ecology and Evolution, University of Chicago, Chicago, IL 60637, USA.
    Allesina, Stefano
    Department of Ecology and Evolution, and Computation Institute, University of Chicago, Chicago, IL 60637, USA.
    Relevance of evolutionary history for food web structure2012Ingår i: Proceedings of the Royal Society of London. Biological Sciences, ISSN 0962-8452, E-ISSN 1471-2954, Vol. 279, nr 1733, s. 1588-1596Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Explaining the structure of ecosystems is one of the great challenges of ecology. Simple models for foodweb structure aim at disentangling the complexity of ecological interaction networks and detect the main forces that are responsible for their shape. Trophic interactions are influenced by species traits, which in turn are largely determined by evolutionary history. Closely related species are more likely to share similar traits, such as body size, feeding mode and habitat preference than distant ones. Here, we present a theoretical framework for analysing whether evolutionary history—represented by taxonomic classification—provides valuable information on food web structure. In doing so, we measure which taxonomic ranks better explain species interactions. Our analysis is based on partitioning of the species into taxonomic units. For each partition, we compute the likelihood that a probabilistic model for food web structurere produces the data using this information. We find that taxonomic partitions produce significantly higher likelihoods than expected at random. Marginal likelihoods (Bayes factors) are used to perform model selection among taxonomic ranks. We show that food webs are best explained by the coarser taxonomic ranks (kingdom to class). Our methods provide a way to explicitly include evolutionary history in models for food web structure.

  • 15.
    Kaneryd, Linda
    et al.
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Teoretisk Biologi. Linköpings universitet, Tekniska högskolan.
    Borrvall, Charlotte
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Teoretisk Biologi. Linköpings universitet, Tekniska högskolan.
    Berg, Sofia
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Teoretisk Biologi. Linköpings universitet, Tekniska högskolan.
    Curtsdotter, Alva
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Teoretisk Biologi. Linköpings universitet, Tekniska högskolan.
    Eklöf, Anna
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Teoretisk Biologi. Linköpings universitet, Tekniska högskolan.
    Hauzy, Céline
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Teoretisk Biologi. Linköpings universitet, Tekniska högskolan.
    Jonsson, Tomas
    Skövde University, Sweden.
    Münger, Peter
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Teoretisk Fysik. Linköpings universitet, Tekniska högskolan.
    Setzer, Malin
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Teoretisk Biologi. Linköpings universitet, Tekniska högskolan.
    Säterberg, Torbjörn
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Teoretisk Biologi. Linköpings universitet, Tekniska högskolan.
    Ebenman, Bo
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Teoretisk Biologi. Linköpings universitet, Tekniska högskolan.
    Species-rich ecosystems are vulnerable to cascading extinctions in an indreasingly variable world2012Ingår i: Ecology and Evolution, ISSN 2045-7758, E-ISSN 2045-7758, Vol. 2, nr 4, s. 858-874Artikel i tidskrift (Refereegranskat)
    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 species-rich ecosystems like coral reefs and tropical rainforests might be particularly vulnerable to increased climate variability.

  • 16.
    Zook, Alexander E
    et al.
    Department of Ecology and Evolution, University of Chicago, United States.
    Eklöf, Anna
    Department of Ecology and Evolution, University of Chicago, United States.
    Jacob, Ute
    Institute for Hydrobiologie and Fisheries Science, University Hamburg, Germany.
    Allesina, Stefano
    Department of Ecology and Evolution, University of Chicago, United States; Computation Institute, University of Chicago, United States.
    Food webs: ordering species according to body size yields high degree of intervality2011Ingår i: Journal of Theoretical Biology, ISSN 0022-5193, E-ISSN 1095-8541, Vol. 271, nr 1, s. 106-113Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Food webs, the networks describing "who eats whom" in an ecosystem, are nearly interval, i.e. there is a way to order the species so that almost all the resources of each consumer are adjacent in the ordering. This feature has important consequences, as it means that the structure of food webs can be described using a single (or few) species' traits. Moreover, exploiting the quasi-intervality found in empirical webs can help build better models for food web structure. Here we investigate which species trait is a good proxy for ordering the species to produce quasi-interval orderings. We find that body size produces a significant degree of intervality in almost all food webs analyzed, although it does not match the maximum intervality for the networks. There is also a great variability between webs. Other orderings based on trophic levels produce a lower level of intervality. Finally, we extend the concept of intervality from predator-centered (in which resources are in intervals) to prey-centered (in which consumers are in intervals). In this case as well we find that body size yields a significant, but not maximal, level of intervality. These results show that body size is an important, although not perfect, trait that shapes species interactions in food webs. This has important implications for the formulation of simple models used to construct realistic representations of food webs.

  • 17.
    Curtsdotter, Alva
    et al.
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Teoretisk Biologi. Linköpings universitet, Tekniska högskolan.
    Binzer, Amrei
    J.F. Blumenbach Institute of Zoology and Anthropology, Georg-August University, Göttingen, Germany.
    Brose, Ulrich
    J.F. Blumenbach Institute of Zoology and Anthropology, Georg-August University, Göttingen, Germany.
    de Castro, Fransisco
    Department of Ecology and Ecological Modelling, University of Potsdam, Germany.
    Ebenman, Bo
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Teoretisk Biologi. Linköpings universitet, Tekniska högskolan.
    Eklöf, Anna
    Department of Ecology and Evolution, University of Chicago, United States.
    O. Riede, Jens
    J.F. Blumenbach Institute of Zoology and Anthropology, Georg-August University, Göttingen, Germany.
    Thierry, Aaron
    Department of Animal and Plant Sciences, University of Sheffield, United Kingdom. Microsoft Research, JJ Thompson Avenue, Cambridge, CB3 0FB, UK.
    Rall, Björn C.
    J.F. Blumenbach Institute of Zoology and Anthropology, Georg-August University, Göttingen, Germany.
    Robustness to secondary extinctions: Comparing trait-based sequential deletions in static and dynamic food webs2011Ingår i: Basic and Applied Ecology, ISSN 1439-1791, E-ISSN 1618-0089, Vol. 12, nr 7, s. 571-580Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The loss of species from ecological communities can unleash a cascade of secondary extinctions, the risk and extent of which are likely to depend on the traits of the species that are lost from the community. To identify species traits that have the greatest impact on food web robustness to species loss we here subject allometrically scaled, dynamical food web models to several deletion sequences based on species’ connectivity, generality, vulnerability or body mass. Further, to evaluate the relative importance of dynamical to topological effects we compare robustness between dynamical and purely topological models. This comparison reveals that the topological approach overestimates robustness in general and for certain sequences in particular. Top-down directed sequences have no or very low impact on robustness in topological analyses, while the dynamical analysis reveals that they may be as important as high-impact bottom-up directed sequences. Moreover, there are no deletion sequences that result, on average, in no or very few secondary extinctions in the dynamical approach. Instead, the least detrimental sequence in the dynamical approach yields an average robustness similar to the most detrimental (non-basal) deletion sequence in the topological approach. Hence, a topological analysis may lead to erroneous conclusions concerning both the relative and the absolute importance of different species traits for robustness. The dynamical sequential deletion analysis shows that food webs are least robust to the loss of species that have many trophic links or that occupy low trophic levels. In contrast to previous studies we can infer, albeit indirectly, that secondary extinctions were triggered by both bottom-up and top-down cascades.

  • 18.
    Riede, Jens O,
    et al.
    J.F. Blumenbach Institute of Zoology and Anthropology, Georg-August University Göttingen, Germany.
    Binzer, Amrei
    J.F. Blumenbach Institute of Zoology and Anthropology, Georg-August University Göttingen, Germany.
    Brose, Ulrich
    J.F. Blumenbach Institute of Zoology and Anthropology, Georg-August University Göttingen, Germany.
    de Castro, Fransisco
    Ecology and Ecological Modelling, University of Potsdam, Germany.
    Curtsdotter, Alva
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Teoretisk Biologi. Linköpings universitet, Tekniska högskolan.
    Rall, Björn C.
    J.F. Blumenbach Institute of Zoology and Anthropology, Georg-August University Göttingen, Germany.
    Eklöf, Anna
    Department of Ecology and Evolution, University of Chicago, United States.
    Size-based food web characteristics govern the response to species extinctions2011Ingår i: Basic and Applied Ecology, ISSN 1439-1791, E-ISSN 1618-0089, Vol. 12, nr 7, s. 581-589Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    How ecological communities react to species extinctions is a long-standing yet current question in ecology. The species constituting the basic units of ecosystems interact with each other forming complex networks of trophic relationships and the characteristics of these networks are highly important for the consequences of species extinction. Here we take a more general approach and analyze a broad range of network characteristics and their role in determining food web susceptibility to secondary extinctions. We extend previous studies, that have focused on the consequences of topological and dynamical foodweb parameters for food web robustness, by also defining network-wide characteristics depending on the relationships between the distribution of species body masses and other species characteristics. We use a bioenergetic dynamical model to simulate realistically structured model food webs that differ in their structural and dynamical properties as well as their size structure. In order to measure food web robustness we calculated the proportion of species going secondarily extinct. A multiple regression analysis was then used to fit a general model relating the proportion of species going secondarily extinct to the measured foodweb properties. Our results show that there are multiple factors from all three groups of food web characteristics that affect foodweb robustness. However, we find the most striking effect was related to the body mass–abundance relationship which points to the importance of body mass relationships for food web stability.

  • 19.
    Binzer, Amrei
    et al.
    J.F. Blumenbach Institute of Zoology and Anthropology, Georg-August University Göttingen, Germany.
    Brose, Ulrich
    J.F. Blumenbach Institute of Zoology and Anthropology, Georg-August University Göttingen, Germany.
    Curtsdotter, Alva
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Teoretisk Biologi. Linköpings universitet, Tekniska högskolan.
    Eklöf, Anna
    Department of Ecology and Evolution, University of Chicago, United States.
    Rall, Björn C.
    J.F. Blumenbach Institute of Zoology and Anthropology, Georg-August University Göttingen, Germany.
    Riede, Jens O.
    J.F. Blumenbach Institute of Zoology and Anthropology, Georg-August University Göttingen, Germany.
    de Castro, Fransisco
    Institute for Biochemistry and Biology, University of Potsdam, Germany.
    The susceptibility of species to extinctions in model communities2011Ingår i: Basic and Applied Ecology, ISSN 1439-1791, E-ISSN 1618-0089, Vol. 12, nr 7, s. 590-599Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Despite the fact that the loss of a species from a community has the potential to cause a dramatic decline in biodiversity, for example through cascades of secondary extinctions, little is known about the factors contributing to the extinction risk of any particular species. Here we expand earlier modeling approaches using a dynamic food-web model that accounts for bottom-up as well as top-down effects. We investigate what factors influence a species’ extinction risk and time to extinction of the non-persistent species. We identified three basic properties that affect a species’ risk of extinction. The highest extinction risk is born by species with (1) low energy input (e.g. high trophic level), (2) susceptibility to the loss of energy pathways (e.g. specialists with few prey species) and (3) dynamic instability (e.g. low Hill exponent and reliance on homogeneous energy channels when feeding on similarly sized prey). Interestingly, and different from field studies, we found that the trophic level and not the body mass of a species influences its extinction risk. On the other hand, body mass is the single most important factor determining the time to extinction of a species, resulting in small species dying first. This suggests that in the field the trophic level might have more influence on the extinction risk than presently recognized.

  • 20.
    Eklöf, Anna
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Teoretisk Biologi. Linköpings universitet, Tekniska högskolan.
    Species extinctions in food webs: local and regional processes2009Doktorsavhandling, sammanläggning (Övrigt vetenskapligt)
    Abstract [en]

    Loss of biodiversity is one of the most severe threats to the ecosystems of the world. The major causes behind the high population and species extinction rates are anthropogenic activities such as overharvesting of natural populations, pollution, climate change and destruction and fragmentation of natural habitats. There is an urgent need of understanding how these species losses affect the ecological structure and functioning of our ecosystems. Ecological communities exist in a landscape but the spatial aspects of community dynamics have until recently to large extent been ignored. However, the community’s response to species losses is likely to depend on both the structure of the local community as well as its interactions with surrounding communities. Also the characteristics of the species going extinct do affect how the community can cope with species loss. The overall goal of the present work has been to investigate how both local and regional processes affect ecosystem stability, in the context of preserved biodiversity and maintained ecosystem functioning. The focus is particularly on how these processes effects ecosystem’s response to species loss. To accomplish this goal I have formulated and analyzed mathematical models of ecological communities. We start by analyzing the local processes (Paper I and II) and continue by adding the regional processes (Paper III, IV and V).

    In Paper I we analyze dynamical models of ecological communities of different complexity (connectance) to investigate how the structure of the communities affects their resistance to species loss. We also investigate how the resistance is affected by the characteristics, like trophic level and connectivity, of the initially lost species. We find that complex communities are more resistant to species loss than simple communities. The loss of species at low trophic levels and/or with high connectivity (many links to other species) triggers, on average, the highest number of secondary extinctions. We also investigate the structure of the post-extinction community. Moreover, we compare our dynamical analysis with results from topological analysis to evaluate the importance of incorporating dynamics when assessing the risk and extent of cascading extinctions.

    The characteristics of a species, like its trophic position and connectivity (number of ingoing and outgoing trophic links) will affect the consequences of its loss as well as its own vulnerability to secondary extinction. In Paper II we characterize the species according to their trophic/ecological uniqueness, a new measure of species characteristic we develop in this paper. A species that has no prey or predators in common with any other species in the community will have a high tropic uniqueness. Here we examine the effect of secondary extinctions on an ecological community’s trophic diversity, the range of different trophic roles played by the species in a community. We find that secondary extinctions cause loss of trophic diversity greater than expected from chance. This occurs because more tropically unique species are more vulnerable to secondary extinctions.

    In Paper III, IV and V we expand the analysis to also include the spatial dimension. Paper III is a book chapter discussing spatial aspects of food webs. In Paper IV we analyze how metacommunities (a set of local communities in the landscape connected by species dispersal) respond to species loss and how this response is affected by the structure of the local communities and the number of patches in the metacommunity. We find that the inclusion of space reduces the risk of global and local extinctions and that lowly connected communities are more sensitive to species loss.

    In Paper V we investigate how the trophic structure of the local communities, the spatial structure of the landscape and the dispersal patterns of species affect the risk of local extinctions in the metacommunity. We find that the pattern of dispersal can have large effects on local diversity. Dispersal rate as well as dispersal distance are important: low dispersal rates and localized dispersal decrease the risk of local and global extinctions while high dispersal rates and global dispersal increase the risk. We also show that the structure of the local communities plays a significant role for the effects of dispersal on the dynamics of the metacommunity. The species that are most affected by the introduction of the spatial dimension are the top predators.

    Delarbeten
    1. Species loss and secondary extinctions in simple and complex model communities
    Öppna denna publikation i ny flik eller fönster >>Species loss and secondary extinctions in simple and complex model communities
    2006 (Engelska)Ingår i: Journal of Animal Ecology, ISSN 0021-8790, E-ISSN 1365-2656, Vol. 75, nr 1, s. 239-246Artikel i tidskrift (Refereegranskat) Published
    Abstract [en]
    1. The loss of a species from an ecological community can trigger a cascade of secondary extinctions. Here we investigate how the complexity (connectance) of model communities affects their response to species loss. Using dynamic analysis based on a global criterion of persistence (permanence) and topological analysis we investigate the extent of secondary extinctions following the loss of different kinds of species.
    2. We show that complex communities are, on average, more resistant to species loss than simple communities: the number of secondary extinctions decreases with increasing connectance. However, complex communities are more vulnerable to loss of top predators than simple communities.
    3. The loss of highly connected species (species with many links to other species) and species at low trophic levels triggers, on average, the largest number of secondary extinctions. The effect of the connectivity of a species is strongest in webs with low connectance.
    4. Most secondary extinctions are due to direct bottom-up effects: consumers go extinct when their resources are lost. Secondary extinctions due to trophic cascades and disruption of predator-mediated coexistence also occur. Secondary extinctions due to disruption of predator-mediated coexistence are more common in complex communities than in simple communities, while bottom-up and top-down extinction cascades are more common in simple communities.
    5. Topological analysis of the response of communities to species loss always predicts a lower number of secondary extinctions than dynamic analysis, especially in food webs with high connectance.
    Ort, förlag, år, upplaga, sidor
    Wiley InterScience, 2006
    Nyckelord
    Cascading extinction, connectance, food web, keystone species, resistance
    Nationell ämneskategori
    Naturvetenskap
    Identifikatorer
    urn:nbn:se:liu:diva-37000 (URN)10.1111/j.1365-2656.2006.01041.x (DOI)000235043700024 ()33326 (Lokalt ID)33326 (Arkivnummer)33326 (OAI)
    Tillgänglig från: 2009-10-10 Skapad: 2009-10-10 Senast uppdaterad: 2017-04-18Bibliografiskt granskad
    2. Trophically Unique Species Are Vulnerable to Cascading Extinction
    Öppna denna publikation i ny flik eller fönster >>Trophically Unique Species Are Vulnerable to Cascading Extinction
    2008 (Engelska)Ingår i: American Naturalist, ISSN 0003-0147, E-ISSN 1537-5323, Vol. 171, nr 5, s. 568-579Artikel i tidskrift (Refereegranskat) Published
    Abstract [en]

    Understanding which species might become extinct and the consequences of such loss is critical. One consequence is a cascade of further, secondary extinctions. While a significant amount is known about the types of communities and species that suffer secondary extinctions, little is known about the consequences of secondary extinctions for biodiversity. Here we examine the effect of these secondary extinctions on trophic diversity, the range of trophic roles played by the species in a community. Our analyses of natural and model food webs show that secondary extinctions cause loss of trophic diversity greater than that expected from chance, a result that is robust to variation in food web structure, distribution of interactions strengths, functional response, and adaptive foraging. Greater than expected loss of trophic diversity occurs because more trophically unique species are more vulnerable to secondary extinction. This is not a straightforward consequence of these species having few links with others but is a complex function of how direct and indirect interactions affect species persistence. A positive correlation between a species’ extinction probability and the importance of its loss defines high-risk species and should make their conservation a priority.

    Ort, förlag, år, upplaga, sidor
    University of Chicago Press, 2008
    Nyckelord
    biodiversity, redundancy, stability, food webs, species deletions
    Nationell ämneskategori
    Naturvetenskap
    Identifikatorer
    urn:nbn:se:liu:diva-11923 (URN)10.1086/587068 (DOI)000255212900004 ()
    Anmärkning

    Original publication: Owen L. Petchey, Anna Eklöf, Charlotte Borrvall and Bo Ebenman, Trophically Unique Species Are Vulnerable to Cascading Extinction, 2008, American Naturalist, (171), 5, 568-579. http://dx.doi.org/10.1086/587068. Copyright © 2008. University of Chicago Press. All rights reserved

    Tillgänglig från: 2008-05-28 Skapad: 2008-05-28 Senast uppdaterad: 2017-04-19Bibliografiskt granskad
    3. Spatial aspects of food webs
    Öppna denna publikation i ny flik eller fönster >>Spatial aspects of food webs
    Visa övriga...
    2005 (Engelska)Ingår i: Dynamic Food Webs: Multispecies Assemblages, Ecosystem Development and Environmental Change / [ed] P.C. deRuiter, V. Wolters & J.C. Moore, London, UK: Elsevier, 2005, Vol. 3, s. 463-469Konferensbidrag, Publicerat paper (Refereegranskat)
    Abstract [en]

    Aspects of spatial scale have until recently been largely ignored in empirical and theoretical food web studies (e.g., Cohen & Briand 1984, Martinez 1992, but see Bengtsson et al. 2002, Bengtsson & Berg, this book). Most ecologists tend to conceptualize and represent food webs as static representations of communities, depicting a community assemblage as sampled at a particular point in time, or highly aggregated trophic group composites over broader scales of time and space (Polis et al. 1996). Moreover, most researchers depict potential food webs, which contain all species sampled and all potential trophic links based on literature reviews, several sampling events, or laboratory feeding trials. In reality, however, not all these potential feeding links are realized as not all species co-occur, and not all samples in space or time can contain all species (Schoenly & Cohen 1991), hence, yielding a variance of food web architecture in space (Brose et al. 2004). In recent years, food web ecologists have recognized that food webs are open systems – that are influence by processes in adjacent systems – and spatially heterogeneous (Polis et al. 1996). This influence of adjacent systems can be bottom-up, due to allochthonous inputs of resources (Polis & Strong 1996, Huxel & McCann 1998, Mulder & De Zwart 2003), or top-down due to the regular or irregular presence of top predators (e.g., Post et al. 2000, Scheu 2001). However, without a clear understanding of the size of a system and a definition of its boundaries it is not possible to judge if flows are internal or driven by adjacent systems. Similarly, the importance of allochthony is only assessable when the balance of inputs and outputs are known relative to the scale and throughputs within the system itself. At the largest scale of the food web – the home range of a predator such as wolf, lion, shark or eagle of roughly 50 km2 to 300 km2 –the balance of inputs and outputs caused by wind and movement of water may be small compared to the total trophic flows within the home range of the large predator (Cousins 1990). Acknowledging these issues of space, Polis et al (1996) argued that progress toward the next phase of food web studies would require addressing spatial and temporal processes. Here, we present a conceptual framework with some nuclei about the role of space in food web ecology. Although we primarily address spatial aspects, this framework is linked to a more general concept of spatio-temporal scales of ecological research.

    Ort, förlag, år, upplaga, sidor
    London, UK: Elsevier, 2005
    Serie
    Theoretical Ecology Series, ISSN 1875-306X
    Nationell ämneskategori
    Ekologi
    Identifikatorer
    urn:nbn:se:liu:diva-31067 (URN)16789 (Lokalt ID)9780120884582 (ISBN)0120884585 (ISBN)16789 (Arkivnummer)16789 (OAI)
    Konferens
    Food Web Symposium 2003, Giessen, Germany, 13-16 November 2003
    Tillgänglig från: 2009-10-09 Skapad: 2009-10-09 Senast uppdaterad: 2015-09-14Bibliografiskt granskad
    4. Cascading extinctions in spatially coupled food webs
    Öppna denna publikation i ny flik eller fönster >>Cascading extinctions in spatially coupled food webs
    (Engelska)Manuskript (preprint) (Övrigt vetenskapligt)
    Abstract [en]

    The spatial structure of ecological communities as well as the dynamics and structure of local communities can be expected to have important consequences for the long-term persistence of metacommunities, that is, their resistance to different kind of perturbations. The aim of the present work is to investigate how web connectance of local communities and number of local habitat patches affects a metacommunity’s response to the global loss of a species. We find that the inclusion of space significantly reduces the risk of global and local cascading extinctions. It is shown that communities with sparsely connected food webs are the most sensitive to species loss, but also that they are particularly well stabilized by the introduction of space. In agreement with theoretical studies of non-spatial habitats, species at the highest trophic level are the most vulnerable to secondary extinction, although they often take the longest time to die out. This is particularly pronounced in spatial habitats, where the top predators appear to be the least well adapted to exploit the stabilizing properties of space.

    Nyckelord
    Cascading extinction, dispersal, food web connectance, habitat destruction, metacommunity, spatial structure, species interactions, species loss
    Nationell ämneskategori
    Naturvetenskap
    Identifikatorer
    urn:nbn:se:liu:diva-51955 (URN)
    Tillgänglig från: 2009-11-24 Skapad: 2009-11-24 Senast uppdaterad: 2009-11-24Bibliografiskt granskad
    5. Effects of dispersal on local extinctions in multi-trophic metacommunities
    Öppna denna publikation i ny flik eller fönster >>Effects of dispersal on local extinctions in multi-trophic metacommunities
    (Engelska)Manuskript (preprint) (Övrigt vetenskapligt)
    Abstract [en]

    As a result of habitat destruction many ecological communities have a fragmented distribution and are built up of partially isolated local communities connected through dispersal of interacting species. The dynamics of such metacommunities is governed both by local processes (interactions among species coexisting within habitat patches) and regional processes (movement of species among habitat patches). Earlier theoretical work on simple metacommunities have mainly focused on the positive effects of space and dispersal for the coexistence of interacting species and hence for local and regional species diversity. However, it is plausible that dispersal might also pose some kind of risk to the dispersing individuals. Here we explore how such risks might affect the dynamics of metacommunities. We develop spatially and dynamically explicit models to investigate how the trophic structure (connectance) of local communities, the spatial structure of the metacommunity and the dispersal characteristics of species affect species extinction risks. Species extinction risks in these open communities are measured relative to the extinction risks in closed communities (i.e. no dispersal). We show that the introduction of dispersal among initially closed local communities might lead to increased probability of local species extinction. The effects of dispersal depend on migration rate, movement pattern of individuals and the density of patches in the landscape. Specifically, when dispersal involves a risk, high migration rates, global dispersal and low patch density will all lead to increased probability of local species extinctions. Furthermore, the trophic structure of local communities plays a significant role in the response of metacommunities to changes in the regional processes.

    Nyckelord
    Dispersal, dispersal risk, extinction, food web connectance, metacommunity, migration rate, spatial structure
    Nationell ämneskategori
    Naturvetenskap
    Identifikatorer
    urn:nbn:se:liu:diva-51956 (URN)
    Tillgänglig från: 2009-11-24 Skapad: 2009-11-24 Senast uppdaterad: 2009-11-24Bibliografiskt granskad
  • 21.
    Petchey, Owen L.
    et al.
    Department of Animal and Plant Sciences, University of Sheffield, United Kingdom.
    Eklöf, Anna
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Teoretisk Biologi. Linköpings universitet, Tekniska högskolan.
    Borrvall, Charlotte
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Teoretisk Biologi. Linköpings universitet, Tekniska högskolan.
    Ebenman, Bo
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Teoretisk Biologi. Linköpings universitet, Tekniska högskolan.
    Trophically Unique Species Are Vulnerable to Cascading Extinction2008Ingår i: American Naturalist, ISSN 0003-0147, E-ISSN 1537-5323, Vol. 171, nr 5, s. 568-579Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Understanding which species might become extinct and the consequences of such loss is critical. One consequence is a cascade of further, secondary extinctions. While a significant amount is known about the types of communities and species that suffer secondary extinctions, little is known about the consequences of secondary extinctions for biodiversity. Here we examine the effect of these secondary extinctions on trophic diversity, the range of trophic roles played by the species in a community. Our analyses of natural and model food webs show that secondary extinctions cause loss of trophic diversity greater than that expected from chance, a result that is robust to variation in food web structure, distribution of interactions strengths, functional response, and adaptive foraging. Greater than expected loss of trophic diversity occurs because more trophically unique species are more vulnerable to secondary extinction. This is not a straightforward consequence of these species having few links with others but is a complex function of how direct and indirect interactions affect species persistence. A positive correlation between a species’ extinction probability and the importance of its loss defines high-risk species and should make their conservation a priority.

  • 22.
    Eklöf, Anna
    et al.
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för fysik, kemi och biologi, Teoretisk Biologi.
    Ebenman, Bo
    Linköpings universitet, Tekniska högskolan. Linköpings universitet, Institutionen för fysik, kemi och biologi, Teoretisk Biologi.
    Species loss and secondary extinctions in simple and complex model communities2006Ingår i: Journal of Animal Ecology, ISSN 0021-8790, E-ISSN 1365-2656, Vol. 75, nr 1, s. 239-246Artikel i tidskrift (Refereegranskat)
    Abstract [en]
    1. The loss of a species from an ecological community can trigger a cascade of secondary extinctions. Here we investigate how the complexity (connectance) of model communities affects their response to species loss. Using dynamic analysis based on a global criterion of persistence (permanence) and topological analysis we investigate the extent of secondary extinctions following the loss of different kinds of species.
    2. We show that complex communities are, on average, more resistant to species loss than simple communities: the number of secondary extinctions decreases with increasing connectance. However, complex communities are more vulnerable to loss of top predators than simple communities.
    3. The loss of highly connected species (species with many links to other species) and species at low trophic levels triggers, on average, the largest number of secondary extinctions. The effect of the connectivity of a species is strongest in webs with low connectance.
    4. Most secondary extinctions are due to direct bottom-up effects: consumers go extinct when their resources are lost. Secondary extinctions due to trophic cascades and disruption of predator-mediated coexistence also occur. Secondary extinctions due to disruption of predator-mediated coexistence are more common in complex communities than in simple communities, while bottom-up and top-down extinction cascades are more common in simple communities.
    5. Topological analysis of the response of communities to species loss always predicts a lower number of secondary extinctions than dynamic analysis, especially in food webs with high connectance.
  • 23.
    Brose, Ulrich
    et al.
    Technical University of Darmstadt, Germany.
    Pavao-Zuckerman, Mitchell
    University of Arizona, Tucson, Arizona, USA.
    Eklöf, Anna
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Teoretisk Biologi. Linköpings universitet, Tekniska högskolan.
    Bengtsson, Janne
    Swedish University of Agricultural Sciences, Uppsala, Sweden.
    Berg, Matty P.
    Vrije Universiteit Amsterdam, The Netherlands.
    Cousins, Steven H.
    Cranfield University, United Kingdom.
    Mulder, Christian
    National Institute for Public Health and the Environment (RIVM), Bilthoven, The Netherlands.
    Verhoef, Herman A.
    Vrije Universiteit Amsterdam, The Netherlands.
    Wolters, Volkmar
    Justus-Liebig-University, Giessen, Germany.
    Spatial aspects of food webs2005Ingår i: Dynamic Food Webs: Multispecies Assemblages, Ecosystem Development and Environmental Change / [ed] P.C. deRuiter, V. Wolters & J.C. Moore, London, UK: Elsevier, 2005, Vol. 3, s. 463-469Konferensbidrag (Refereegranskat)
    Abstract [en]

    Aspects of spatial scale have until recently been largely ignored in empirical and theoretical food web studies (e.g., Cohen & Briand 1984, Martinez 1992, but see Bengtsson et al. 2002, Bengtsson & Berg, this book). Most ecologists tend to conceptualize and represent food webs as static representations of communities, depicting a community assemblage as sampled at a particular point in time, or highly aggregated trophic group composites over broader scales of time and space (Polis et al. 1996). Moreover, most researchers depict potential food webs, which contain all species sampled and all potential trophic links based on literature reviews, several sampling events, or laboratory feeding trials. In reality, however, not all these potential feeding links are realized as not all species co-occur, and not all samples in space or time can contain all species (Schoenly & Cohen 1991), hence, yielding a variance of food web architecture in space (Brose et al. 2004). In recent years, food web ecologists have recognized that food webs are open systems – that are influence by processes in adjacent systems – and spatially heterogeneous (Polis et al. 1996). This influence of adjacent systems can be bottom-up, due to allochthonous inputs of resources (Polis & Strong 1996, Huxel & McCann 1998, Mulder & De Zwart 2003), or top-down due to the regular or irregular presence of top predators (e.g., Post et al. 2000, Scheu 2001). However, without a clear understanding of the size of a system and a definition of its boundaries it is not possible to judge if flows are internal or driven by adjacent systems. Similarly, the importance of allochthony is only assessable when the balance of inputs and outputs are known relative to the scale and throughputs within the system itself. At the largest scale of the food web – the home range of a predator such as wolf, lion, shark or eagle of roughly 50 km2 to 300 km2 –the balance of inputs and outputs caused by wind and movement of water may be small compared to the total trophic flows within the home range of the large predator (Cousins 1990). Acknowledging these issues of space, Polis et al (1996) argued that progress toward the next phase of food web studies would require addressing spatial and temporal processes. Here, we present a conceptual framework with some nuclei about the role of space in food web ecology. Although we primarily address spatial aspects, this framework is linked to a more general concept of spatio-temporal scales of ecological research.

  • 24.
    Eklöf, Anna
    Linköpings universitet, Institutionen för fysik och mätteknik. Linköpings universitet, Tekniska högskolan.
    Cascading extinctions in food webs: local and regional processes2004Licentiatavhandling, sammanläggning (Övrigt vetenskapligt)
    Abstract [en]

    Ecological communities all over the world are loosing biodiversity due to different kinds of human activities and there is an urgent need of understanding how those losses affect the function of the ecosystems on which we all depend. The community's response to species losses is likely to depend on both the structure of the local community as well as its interactions with surrounding communities. Also the characteristics of the species going extinct do affect how the community structure changes. The main purpose of this thesis is to study how local population dynamics and regional processes in food webs affect ecological communities' response to species loss, especially the risk of cascading extinctions.

    In Paper I we use a set of model food webs with different shapes and connectance to look at how the structure of the community affects its resistance to species loss. We also investigate how the resistance is affected by which species, according to trophic level and connectivity, that is lost initially. What we find is that food webs with lower connectance seem to be more vulnerable than more connected communities. The loss of a species at low trophic level and / or with high connectivity triggers the on average highest number of secondary extinctions. We also discuss about the structure of the post­ extinction community and compare our analysis with topological studies.

    In paper Il we use as set of metacommunities with different connectances and different number of patches and we vary the dispersal distances and migration rates. The aim of this paper is to investigate how web connectance of local communities, number of habitat patches and dispersal patterns affects a metacommunity's response to the global loss of a species. We find that asynchrony among patch dynamics may arise from relatively low rates of migration, and that the inclusion of space significantly reduces the risk of global cascading extinctions. It is shown that communities with sparsely connected food webs are the most sensitive to species loss, but also that they are particularly well stabilised by the introduction of space. In agreement with theoretical studies of non-spatial habitats, species at the highest trophic level are the most vulnerable to secondary extinction.

    Paper III is a book chapter that emerged from a working group during a food web symposium in Giessen, Germany 2003. It is dealing with ideas of how to look at spatial aspects of food webs.

  • 25.
    Eklöf, Anna
    et al.
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Teoretisk Biologi. Linköpings universitet, Tekniska högskolan.
    Münger, Peter
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Teoretisk Fysik. Linköpings universitet, Tekniska högskolan.
    Kaneryd, Linda
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Teoretisk Biologi. Linköpings universitet, Tekniska högskolan.
    Ebenman, Bo
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Teoretisk Biologi. Linköpings universitet, Tekniska högskolan.
    Can dispersal rescue metacommunities from extinction cascades?Manuskript (preprint) (Övrigt vetenskapligt)
    Abstract [en]

    Climate change and habitat loss are increasingly affecting the structure and dynamics of ecological communities both at the local and regional scale. Changes in the spatial structure of landscapes as well as in the trophic structure of local communities can be expected to have important consequences for the long-term persistence of species in metacommunities. The aim of the present work is to investigate how the spatial structure of the landscape (patch density) and dispersal patterns of species (migration rate and dispersal distance) affect a metacommunities response to local loss of species and to increased mortality of individuals during dispersal. Using a spatially and dynamically explicit metacommunity model we find that the effect of dispersal on metacommunity persistence is two-sided: on the one hand, when dispersal involves no risk, high migration rate significantly reduces the risk of bottom-up extinction cascades following the local removal of a species. The explanation for this is that recolonization rates of the locally removed species increases with increasing migration rate. On the other hand, when dispersal imposes a risk to the dispersing individuals, high migration rate increases extinction risks, especially when dispersal is global (long dispersal distances). Largebodied species with long generation times at the highest trophic level are particularly vulnerable to extinction when dispersal involves a risk. These results suggest that decreasing the mortality risk of dispersing individuals by improving the quality of the habitat matrix might greatly increase the robustness of metacommunities to local loss of species by enhancing recolonizations and rescue effects.

  • 26.
    Eklöf, Anna
    et al.
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Teoretisk Biologi. Linköpings universitet, Tekniska högskolan.
    Platts, Philip
    Ebenman, Bo
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Teoretisk Biologi. Linköpings universitet, Tekniska högskolan.
    Cascading extinctions in spatially coupled food websManuskript (preprint) (Övrigt vetenskapligt)
    Abstract [en]

    The spatial structure of ecological communities as well as the dynamics and structure of local communities can be expected to have important consequences for the long-term persistence of metacommunities, that is, their resistance to different kind of perturbations. The aim of the present work is to investigate how web connectance of local communities and number of local habitat patches affects a metacommunity’s response to the global loss of a species. We find that the inclusion of space significantly reduces the risk of global and local cascading extinctions. It is shown that communities with sparsely connected food webs are the most sensitive to species loss, but also that they are particularly well stabilized by the introduction of space. In agreement with theoretical studies of non-spatial habitats, species at the highest trophic level are the most vulnerable to secondary extinction, although they often take the longest time to die out. This is particularly pronounced in spatial habitats, where the top predators appear to be the least well adapted to exploit the stabilizing properties of space.

  • 27.
    Eklöf, Anna
    et al.
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Teoretisk Biologi. Linköpings universitet, Tekniska högskolan.
    Münger, Peter
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Teoretisk Fysik. Linköpings universitet, Tekniska högskolan.
    Ebenman, Bo
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Teoretisk Biologi. Linköpings universitet, Tekniska högskolan.
    Effects of dispersal on local extinctions in multi-trophic metacommunitiesManuskript (preprint) (Övrigt vetenskapligt)
    Abstract [en]

    As a result of habitat destruction many ecological communities have a fragmented distribution and are built up of partially isolated local communities connected through dispersal of interacting species. The dynamics of such metacommunities is governed both by local processes (interactions among species coexisting within habitat patches) and regional processes (movement of species among habitat patches). Earlier theoretical work on simple metacommunities have mainly focused on the positive effects of space and dispersal for the coexistence of interacting species and hence for local and regional species diversity. However, it is plausible that dispersal might also pose some kind of risk to the dispersing individuals. Here we explore how such risks might affect the dynamics of metacommunities. We develop spatially and dynamically explicit models to investigate how the trophic structure (connectance) of local communities, the spatial structure of the metacommunity and the dispersal characteristics of species affect species extinction risks. Species extinction risks in these open communities are measured relative to the extinction risks in closed communities (i.e. no dispersal). We show that the introduction of dispersal among initially closed local communities might lead to increased probability of local species extinction. The effects of dispersal depend on migration rate, movement pattern of individuals and the density of patches in the landscape. Specifically, when dispersal involves a risk, high migration rates, global dispersal and low patch density will all lead to increased probability of local species extinctions. Furthermore, the trophic structure of local communities plays a significant role in the response of metacommunities to changes in the regional processes.

  • 28.
    Kaneryd, Linda
    et al.
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Teoretisk Biologi. Linköpings universitet, Tekniska högskolan.
    Münger, Peter
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Teoretisk Fysik. Linköpings universitet, Tekniska högskolan.
    Eklöf, Anna
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Teoretisk Biologi. Linköpings universitet, Tekniska högskolan.
    Ebenman, Bo
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Teoretisk Biologi. Linköpings universitet, Tekniska högskolan.
    Risk of global extinctions in metacommunities exposed to a highly variable environment: local and spatial processesManuskript (preprint) (Övrigt vetenskapligt)
    Abstract [en]

    Here we analyze how metacommunities (a set of local communities coupled by species dispersal) in spatially explicit landscapes respond to environmental variation. We examine how this response is affected by 1) species richness in the local communities, 2) the degree of correlation in species response to the environmental variation both between species within patches (species correlation) and among patches (spatial correlation) and 3) dispersal pattern of species. We find that the risk of global extinction increases with increasing species richness in the local communities and with decreasing correlation among species in their response to environmental fluctuations. We also show that the pattern of spatial correlation is of great importance; the risk of global extinctions increases with increasing spatial correlation. Moreover, we find that the pattern and rate of dispersal are important; a high migration rate in combination with localized dispersal decrease the risk of global extinctions whereas a global dispersal pattern increases the risk of global extinctions. When dispersal is global the subpopulations of a species become more synchronized which reduces the potential for a patch to become recolonized following extinctions. We also demonstrate the importance of both local and spatial processes when examining the temporal stability of primary production at the scale of metapopulations, local communities and metacommunities.

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