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  • 1.
    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.

  • 2. Beställ onlineKöp publikationen >>
    Curtsdotter, Alva
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Teoretisk Biologi. Linköpings universitet, Tekniska högskolan.
    Extinctions in Ecological Communities: direct and indirect effects of perturbation on biodiversity2014Doktorsavhandling, sammanläggning (Övrigt vetenskapligt)
    Abstract [en]

    In the dawning of what may become Earth’s 6th mass extinction the topic of this thesis, understanding extinction processes and what determines the magnitude of species loss, has become only too relevant. The number of known extinctions (~850) during the last centuries translates to extinction rates elevated above the background rate, matching those of previous mass extinction events. The main drivers of these extinctions have been human land use, introduction of exotic species and overexploitation. Under continued anthropogenic pressure and climate change, the current extinction rates are predicted to increase tenfold.

    Large perturbations, such as the extinction drivers mentioned above, affects species directly, causing a change in their abundance. As species are not isolated, but connected to each other through a multitude of interactions, the change in abundance of one species can in turn affect others. Thus, in addition to the direct effect, a perturbation can affect a species indirectly through the ecological network in which the species is embedded. With this thesis, I wish to contribute to our basic understanding of these indirect effects and the role they play in determining the magnitude of species loss. All the studies included here are so called in silico experiments, using mathematical models to describe ecological communities and computer simulations to observe the response of these communities to perturbation.

    When a perturbation is severe enough, a species will be driven to extinction. The loss of a species from a system is in itself a large perturbation, and may result in further extinctions, so called secondary extinctions. The traits of the species initially lost, can be a potential predictor of the magnitude of secondary species loss. In Paper I of this thesis, I show that when making such predictions, it is important to incorporate temporally dynamic species interactions and abundances, in order not to underestimate the importance of certain species, such as top predators.

    I further show that species traits alone are not particularly good predictors of secondary extinction risk (Paper I), but that in combination with community level properties they are (Paper II). Indeed, there seems to be an interaction such that the specific property making a community prone to secondary species loss, depends on what kind of species was lost in the primary extinction. As different types of perturbation put different types of species at risk of (primary) extinction, this means that the specific property making a community prone to secondary species loss, will depend on the type of perturbation the community is subjected to.

    One of the predicted main drivers of future species extinction is climate change. If the local climate becomes adverse, a species can either migrate to new and better areas or stay and evolve. Both these processes will be important in determining the magnitude of species loss under climate change. However, migration and evolution do not occur in vacuum – the biotic community in which these processes play out may modulate their effect on biodiversity. In paper III, I show that the strength of competition between species modulates the effect of both dispersal and evolution on the magnitude of species loss under climate change. The three-way interaction between interspecific competition, evolution and dispersal, creates a complex pattern of biodiversity responses, in which both evolution and dispersal can either increase or decrease the magnitude of species loss. Thus, when species interactions are incorporated, it is clear that even though migration and evolution may alleviate the impact of climate change for some species, they may indirectly aggravate the situation for others.

    In Paper III, the aspect of climate change incorporated in the model is an increase in mean annual temperature. But climate change is also predicted to increase environmental variability. Paper IV shows that species-rich communities are more sensitive to high environmental variability than species-poor ones. The smaller population sizes in the species-rich communities increased the extinction risk connected to population fluctuations driven by the variable environment. Hence, systems such as tropical forests and coral reefs are predicted to be particularly sensitive to the increased variability that may follow with climate change.

    In Paper IV, primary extinctions of primary producers result in extinction cascades of consumer species, when they lose their prey. However, in reality a consumer species might be able to switch to another prey, and such flexibility has both been observed and suggested as a potential rescue mechanism. But what is beneficial for an individual predator in the short-term can become detrimental to the ecological community in the long-term. Paper V shows that consumer flexibility often led to consumers continuously overexploiting their new prey, in the worst case to the point of system collapse. Thus, the suggested rescue mechanism aggravated the effect of initial species loss, rather than ameliorating it.

    Overall, the research presented here, underscores the importance of including population dynamics and biotic interactions when studying the effects of perturbation on biodiversity. Many of the results are complex, hard to foresee or even counter-intuitive, arising from the indirect effects of the perturbation being translated through the living web of species interactions.

    Delarbeten
    1. Robustness to secondary extinctions: Comparing trait-based sequential deletions in static and dynamic food webs
    Öppna denna publikation i ny flik eller fönster >>Robustness to secondary extinctions: Comparing trait-based sequential deletions in static and dynamic food webs
    Visa övriga...
    2011 (Engelska)Ingår i: Basic and Applied Ecology, ISSN 1439-1791, E-ISSN 1618-0089, Vol. 12, nr 7, s. 571-580Artikel i tidskrift (Refereegranskat) Published
    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.

    Ort, förlag, år, upplaga, sidor
    Elsevier, 2011
    Nationell ämneskategori
    Naturvetenskap
    Identifikatorer
    urn:nbn:se:liu:diva-73611 (URN)10.1016/j.baae.2011.09.008 (DOI)000299149700003 ()
    Anmärkning

    funding agencies|European Science Foundation||German Research Foundation| BR 2315/11-1 |

    Tillgänglig från: 2012-01-10 Skapad: 2012-01-10 Senast uppdaterad: 2017-04-19
    2. The interaction between species traits and community properties determine food web resistance to species loss
    Öppna denna publikation i ny flik eller fönster >>The interaction between species traits and community properties determine food web resistance to species loss
    2014 (Engelska)Manuskript (preprint) (Övrigt vetenskapligt)
    Abstract [en]

    The ability to identify the ecosystems most vulnerable to species loss is fundamental for the allocation of conservation efforts. With this aim, the traits of keystone species have been investigated, as have the properties defining systems especially sensitive to species loss. However, these two have rarely been investigated in relation to each other. Here we show, that the traits of the species primarily lost act in conjunction with the properties of the food web from which it is lost, in determining the resistance of the system. We find that the extent of bottom-up extinction cascades is determined mainly by traits related to food web topology, while traits related to population dynamics govern the extent of top-down cascades. As different disturbances affect species with different traits, this interaction implies that the characteristics defining a sensitive community depend on the disturbance it is subjected to.

    Nyckelord
    Sequential deletion, species loss, perturbation, stability, robustness, secondary extinction cascades, top-predator loss, meso-predator release, body size, allometric relationships, functional response.
    Nationell ämneskategori
    Annan biologi
    Identifikatorer
    urn:nbn:se:liu:diva-108903 (URN)
    Tillgänglig från: 2014-07-11 Skapad: 2014-07-11 Senast uppdaterad: 2014-07-11Bibliografiskt granskad
    3. The strength of interspecific competition modulates the eco-evolutionary response to climate change
    Öppna denna publikation i ny flik eller fönster >>The strength of interspecific competition modulates the eco-evolutionary response to climate change
    Visa övriga...
    2014 (Engelska)Manuskript (preprint) (Övrigt vetenskapligt)
    Abstract [en]

    Climate change is predicted to have major implications for global biodiversity. Dispersal and evolution may become crucial for species survival, as species must either adapt or migrate to track the changing climate. However, migration and evolution do not occur in vacuum – the biotic community in which these processes play out may modulate their effect on biodiversity. Here, we use an eco-evolutionary, spatially explicit, multi-species model that allows us to examine the interactive effects of competition, adaptation and dispersal on species richness in plant communities under global warming. We find that there is a larger decline in global species richness when interspecific competition is strong. Furthermore, there is a three-way interaction between interspecific competition, evolution and dispersal that creates a complex pattern of biodiversity responses, in which both evolution and dispersal can either increase or decrease the magnitude of species loss. This interaction arises for at least two reasons: 1) different levels of dispersal, evolution and competition creates differences in local and global community structure before climate change, and 2) competitive interactions determine whether the benefits of dispersal and/or evolution (climate tracking and adaptation) outweighs the risks (competitive exclusion).

    Nyckelord
    Climate change, increased temperature, biodiversity loss, species extinctions, competition communities, dispersal, migration, invasion, evolution, local adaptation, tolerance curves
    Nationell ämneskategori
    Annan biologi
    Identifikatorer
    urn:nbn:se:liu:diva-108904 (URN)
    Tillgänglig från: 2014-07-11 Skapad: 2014-07-11 Senast uppdaterad: 2014-07-11Bibliografiskt granskad
    4. Species-rich ecosystems are vulnerable to cascading extinctions in an indreasingly variable world
    Öppna denna publikation i ny flik eller fönster >>Species-rich ecosystems are vulnerable to cascading extinctions in an indreasingly variable world
    Visa övriga...
    2012 (Engelska)Ingår i: Ecology and Evolution, ISSN 2045-7758, E-ISSN 2045-7758, Vol. 2, nr 4, s. 858-874Artikel i tidskrift (Refereegranskat) Published
    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.

    Ort, förlag, år, upplaga, sidor
    John Wiley & Sons, 2012
    Nyckelord
    Biodiversity; climate change; environmental variability; ecological networks; extinction cascades; food-web; species interactions; stability; stochastic models; weather extremes
    Nationell ämneskategori
    Naturvetenskap
    Identifikatorer
    urn:nbn:se:liu:diva-74700 (URN)10.1002/ece3.218 (DOI)000312444000015 ()
    Tillgänglig från: 2012-02-05 Skapad: 2012-02-05 Senast uppdaterad: 2017-12-08Bibliografiskt granskad
    5. Adaptive rewiring aggravates the effects of species loss in ecosystems
    Öppna denna publikation i ny flik eller fönster >>Adaptive rewiring aggravates the effects of species loss in ecosystems
    2015 (Engelska)Ingår i: Nature Communications, ISSN 2041-1723, E-ISSN 2041-1723, Vol. 6, artikel-id 8412Artikel i tidskrift (Refereegranskat) Published
    Abstract [en]

    Loss of one species in an ecosystem can trigger extinctions of other dependent species. For instance, specialist predators will go extinct following the loss of their only prey unless they can change their diet. It has therefore been suggested that an ability of consumers to rewire to novel prey should mitigate the consequences of species loss by reducing the risk of cascading extinction. Using a new modelling approach on natural and computer-generated food webs we find that, on the contrary, rewiring often aggravates the effects of species loss. This is because rewiring can lead to overexploitation of resources, which eventually causes extinction cascades. Such a scenario is particularly likely if prey species cannot escape predation when rare and if predators are efficient in exploiting novel prey. Indeed, rewiring is a two-edged sword; it might be advantageous for individual predators in the short term, yet harmful for long-term system persistence.

    Ort, förlag, år, upplaga, sidor
    Nature Publishing Group, 2015
    Nyckelord
    Resistance, extinction risk, secondary extinction cascades, environmental variation, stochastic, response diversity, functional responses
    Nationell ämneskategori
    Biologiska vetenskaper
    Identifikatorer
    urn:nbn:se:liu:diva-108905 (URN)10.1038/ncomms9412 (DOI)000363138400004 ()
    Anmärkning

    Funding text: Linkoping University.

    The original titel of this article was Adaptive rewiring aggravates the effects of species loss in ecological networks.

    Tillgänglig från: 2014-07-11 Skapad: 2014-07-11 Senast uppdaterad: 2019-12-02Bibliografiskt granskad
    Ladda ner fulltext (pdf)
    Extinctions in Ecological Communities: direct and indirect effects of perturbation on biodiversity
    Ladda ner (pdf)
    omslag
  • 3.
    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.

    Ladda ner fulltext (pdf)
    fulltext
  • 4.
    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.
    Ebenman, Bo
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Teoretisk Biologi. Linköpings universitet, Tekniska högskolan.
    The interaction between species traits and community properties determine food web resistance to species loss2014Manuskript (preprint) (Övrigt vetenskapligt)
    Abstract [en]

    The ability to identify the ecosystems most vulnerable to species loss is fundamental for the allocation of conservation efforts. With this aim, the traits of keystone species have been investigated, as have the properties defining systems especially sensitive to species loss. However, these two have rarely been investigated in relation to each other. Here we show, that the traits of the species primarily lost act in conjunction with the properties of the food web from which it is lost, in determining the resistance of the system. We find that the extent of bottom-up extinction cascades is determined mainly by traits related to food web topology, while traits related to population dynamics govern the extent of top-down cascades. As different disturbances affect species with different traits, this interaction implies that the characteristics defining a sensitive community depend on the disturbance it is subjected to.

  • 5.
    Curtsdotter, Alva
    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.
    Norberg, Jon
    Department of Systems Ecology, Stockholm University/Stockholm Resilience Centre, Stockholm University, Sweden.
    Åkesson, Anna
    Linköpings universitet, Institutionen för fysik, kemi och biologi. Linköpings universitet, Tekniska högskolan.
    Ebenman, Bo
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Teoretisk Biologi. Linköpings universitet, Tekniska högskolan.
    The strength of interspecific competition modulates the eco-evolutionary response to climate change2014Manuskript (preprint) (Övrigt vetenskapligt)
    Abstract [en]

    Climate change is predicted to have major implications for global biodiversity. Dispersal and evolution may become crucial for species survival, as species must either adapt or migrate to track the changing climate. However, migration and evolution do not occur in vacuum – the biotic community in which these processes play out may modulate their effect on biodiversity. Here, we use an eco-evolutionary, spatially explicit, multi-species model that allows us to examine the interactive effects of competition, adaptation and dispersal on species richness in plant communities under global warming. We find that there is a larger decline in global species richness when interspecific competition is strong. Furthermore, there is a three-way interaction between interspecific competition, evolution and dispersal that creates a complex pattern of biodiversity responses, in which both evolution and dispersal can either increase or decrease the magnitude of species loss. This interaction arises for at least two reasons: 1) different levels of dispersal, evolution and competition creates differences in local and global community structure before climate change, and 2) competitive interactions determine whether the benefits of dispersal and/or evolution (climate tracking and adaptation) outweighs the risks (competitive exclusion).

  • 6.
    Digel, Christoph
    et al.
    University of Gottingen, Germany.
    Curtsdotter, Alva
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Teoretisk Biologi. Linköpings universitet, Tekniska högskolan.
    Riede, Jens
    Deutsch Wetterdienst, Germany.
    Klarner, Bernhard
    University of Gottingen, Germany.
    Brose, Ulrich
    University of Gottingen, Germany.
    Unravelling the complex structure of forest soil food webs: higher omnivory and more trophic levels2014Ingår i: Oikos, ISSN 0030-1299, E-ISSN 1600-0706, Vol. 123, nr 10, s. 1157-1172Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Food web topologies depict the community structure as distributions of feeding interactions across populations. Although the soil ecosystem provides important functions for aboveground ecosystems, data on complex soil food webs is notoriously scarce, most likely due to the difficulty of sampling and characterizing the system. To fill this gap we assembled the complex food webs of 48 forest soil communities. The food webs comprise 89 to 168 taxa and 729 to 3344 feeding interactions. The feeding links were established by combining several molecular methods (stable isotope, fatty acid and molecular gut content analyses) with feeding trials and literature data. First, we addressed whether soil food webs (n = 48) differ significantly from those of other ecosystem types (aquatic and terrestrial aboveground, n = 77) by comparing 22 food web parameters. We found that our soil food webs are characterized by many omnivorous and cannibalistic species, more trophic chains and intraguild-predation motifs than other food webs and high average and maximum trophic levels. Despite this, we also found that soil food webs have a similar connectance as other ecosystems, but interestingly a higher link density and clustering coefficient. These differences in network structure to other ecosystem types may be a result of ecosystem specific constraints on hunting and feeding characteristics of the species that emerge as network parameters at the food-web level. In a second analysis of land-use effects, we found significant but only small differences of soil food web structure between different beech and coniferous forest types, which may be explained by generally strong selection effects of the soil that are independent of human land use. Overall, our study has unravelled some systematic structures of soil food-webs, which extends our mechanistic understanding how environmental characteristics of the soil ecosystem determine patterns at the community level.

  • 7.
    Gilljam, David
    et al.
    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.
    Ebenman, Bo
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Teoretisk Biologi. Linköpings universitet, Tekniska högskolan.
    Adaptive rewiring aggravates the effects of species loss in ecosystems2015Ingår i: Nature Communications, ISSN 2041-1723, E-ISSN 2041-1723, Vol. 6, artikel-id 8412Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Loss of one species in an ecosystem can trigger extinctions of other dependent species. For instance, specialist predators will go extinct following the loss of their only prey unless they can change their diet. It has therefore been suggested that an ability of consumers to rewire to novel prey should mitigate the consequences of species loss by reducing the risk of cascading extinction. Using a new modelling approach on natural and computer-generated food webs we find that, on the contrary, rewiring often aggravates the effects of species loss. This is because rewiring can lead to overexploitation of resources, which eventually causes extinction cascades. Such a scenario is particularly likely if prey species cannot escape predation when rare and if predators are efficient in exploiting novel prey. Indeed, rewiring is a two-edged sword; it might be advantageous for individual predators in the short term, yet harmful for long-term system persistence.

  • 8.
    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.

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  • 9.
    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.

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