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Galiana N, Arnoldi JF, Mestre F, Rozenfeld A, Araújo MB. Power laws in species' biotic interaction networks can be inferred from co-occurrence data. Nat Ecol Evol 2024; 8:209-217. [PMID: 38012361 DOI: 10.1038/s41559-023-02254-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2023] [Accepted: 10/17/2023] [Indexed: 11/29/2023]
Abstract
Inferring biotic interactions from species co-occurrence patterns has long intrigued ecologists. Yet recent research revealed that co-occurrences may not reliably represent pairwise biotic interactions. We propose that examining network-level co-occurrence patterns can provide valuable insights into community structure and assembly. Analysing ten bipartite networks of empirically sampled biotic interactions and associated species spatial distribution, we find that approximately 20% of co-occurrences correspond to actual interactions. Moreover, the degree distribution shifts from exponential in co-occurrence networks to power laws in networks of biotic interactions. This shift results from a strong interplay between species' biotic (their interacting partners) and abiotic (their environmental requirements) niches, and is accurately predicted by considering co-occurrence frequencies. Our work offers a mechanistic understanding of the assembly of ecological communities and suggests simple ways to infer fundamental biotic interaction network characteristics from co-occurrence data.
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Affiliation(s)
- Nuria Galiana
- Department of Biogeography and Global Change, National Museum of Natural Sciences, Madrid, Spain.
| | - Jean-François Arnoldi
- Centre National de la Recherche Scientifique, Experimental and Theoretical Ecology Station, Moulis, France
| | - Frederico Mestre
- Rui Nabeiro Biodiversity Chair, Mediterranean Institute for Agriculture, Environment and Development, University of Évora, Évora, Portugal
| | - Alejandro Rozenfeld
- Rui Nabeiro Biodiversity Chair, Mediterranean Institute for Agriculture, Environment and Development, University of Évora, Évora, Portugal
- INTELYMEC Group, Centro de Investigaciones en Física e Ingeniería del Centro Centro de Investigaciones en Física e Ingeniería del Centro de la Provincia de Buenos Aires - Universidad Nacional del Centro de la Provincia de Buenos Aires - Consejo Nacional de Investigaciones Científicas y Técnicas, Olavarría, Argentina
| | - Miguel B Araújo
- Department of Biogeography and Global Change, National Museum of Natural Sciences, Madrid, Spain
- Rui Nabeiro Biodiversity Chair, Mediterranean Institute for Agriculture, Environment and Development, University of Évora, Évora, Portugal
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2
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Ecological network complexity scales with area. Nat Ecol Evol 2022; 6:307-314. [PMID: 35027724 PMCID: PMC7614050 DOI: 10.1038/s41559-021-01644-4] [Citation(s) in RCA: 18] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2021] [Accepted: 12/01/2021] [Indexed: 01/17/2023]
Abstract
Larger geographical areas contain more species-an observation raised to a law in ecology. Less explored is whether biodiversity changes are accompanied by a modification of interaction networks. We use data from 32 spatial interaction networks from different ecosystems to analyse how network structure changes with area. We find that basic community structure descriptors (number of species, links and links per species) increase with area following a power law. Yet, the distribution of links per species varies little with area, indicating that the fundamental organization of interactions within networks is conserved. Our null model analyses suggest that the spatial scaling of network structure is determined by factors beyond species richness and the number of links. We demonstrate that biodiversity-area relationships can be extended from species counts to higher levels of network complexity. Therefore, the consequences of anthropogenic habitat destruction may extend from species loss to wider simplification of natural communities.
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3
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Yang F, Liu B, Zhu Y, Wyckhuys KAG, van der Werf W, Lu Y. Species diversity and food web structure jointly shape natural biological control in agricultural landscapes. Commun Biol 2021; 4:979. [PMID: 34408250 PMCID: PMC8373963 DOI: 10.1038/s42003-021-02509-z] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2021] [Accepted: 08/01/2021] [Indexed: 01/01/2023] Open
Abstract
Land-use change and agricultural intensification concurrently impact natural enemy (e.g., parasitoid) communities and their associated ecosystem services (ESs), i.e., biological pest control. However, the extent to which (on-farm) parasitoid diversity and food webs mediate landscape-level influences on biological control remains poorly understood. Here, drawing upon a 3-year study of quantitative parasitoid-hyperparasitoid trophic networks from 25 different agro-landscapes, we assess the cascading effects of landscape composition, species diversity and trophic network structure on ecosystem functionality (i.e., parasitism, hyperparasitism). Path analysis further reveals cascaded effects leading to biological control of a resident crop pest, i.e., Aphis gossypii. Functionality is dictated by (hyper)parasitoid diversity, with its effects modulated by food web generality and vulnerability. Non-crop habitat cover directly benefits biological control, whereas secondary crop cover indirectly lowers hyperparasitism. Our work underscores a need to simultaneously account for on-farm biodiversity and trophic interactions when investigating ESs within dynamic agro-landscapes.
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Affiliation(s)
- Fan Yang
- State Key Laboratory for Biology of Plant Diseases and Insect Pests, Institute of Plant Protection, Chinese Academy of Agricultural Sciences, Beijing, China
| | - Bing Liu
- State Key Laboratory for Biology of Plant Diseases and Insect Pests, Institute of Plant Protection, Chinese Academy of Agricultural Sciences, Beijing, China
| | - Yulin Zhu
- State Key Laboratory for Biology of Plant Diseases and Insect Pests, Institute of Plant Protection, Chinese Academy of Agricultural Sciences, Beijing, China
| | - Kris A G Wyckhuys
- State Key Laboratory for Biology of Plant Diseases and Insect Pests, Institute of Plant Protection, Chinese Academy of Agricultural Sciences, Beijing, China
- University of Queensland, Brisbane, Queensland, Australia
| | - Wopke van der Werf
- Centre for Crop Systems Analysis, Wageningen University and Research, Wageningen, The Netherlands
| | - Yanhui Lu
- State Key Laboratory for Biology of Plant Diseases and Insect Pests, Institute of Plant Protection, Chinese Academy of Agricultural Sciences, Beijing, China.
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4
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Morrison BML, Dirzo R. Distinct responses of antagonistic and mutualistic networks to agricultural intensification. Ecology 2020; 101:e03116. [PMID: 32530504 DOI: 10.1002/ecy.3116] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/03/2019] [Revised: 03/18/2020] [Accepted: 05/04/2020] [Indexed: 11/08/2022]
Abstract
Species interaction networks, which govern the maintenance of biodiversity and ecosystem processes within ecological communities, are being rapidly altered by anthropogenic activities worldwide. Studies on the response of species interaction networks to anthropogenic disturbance have almost exclusively focused on one interaction type at a time, such as mutualistic or antagonistic interactions, making it challenging to decipher how networks of different interaction types respond to the same anthropogenic disturbance. Moreover, few studies have simultaneously focused on the two main components of network structure: network topology (i.e., architecture) and network ecology (i.e., species identities and interaction turnover), thereby limiting our understanding of the ecological drivers underlying changes in network topology in response to anthropogenic disturbance. Here, we used 16,400 plant-pollinator and plant-herbivore interaction observations from 16 sites along an agricultural intensification gradient to compare changes in network topology and ecology between mutualistic and antagonistic networks. We measured two aspects of network topology-nestedness and modularity-and found that although the mutualistic networks were consistently more nested than antagonistic networks and antagonistic networks were consistently more modular, the rate of change in nestedness and modularity along the gradient was comparable between the two network types. Change in network ecology, however, was distinct between mutualistic and antagonistic networks, with partner switching making a significantly larger contribution to interaction turnover in the mutualistic networks than in the antagonistic networks, and species turnover being a strong contributor to interaction turnover in the antagonistic networks. The ecological and topological changes we observed in the antagonistic and mutualistic networks have different implications for pollinator and herbivore communities in agricultural landscapes, and support the idea that pollinators are more labile in their interaction partner choice, whereas herbivores form more reciprocally specialized, and therefore more vulnerable, interactions. Our results also demonstrate that studying both topological and ecological network structure can help to elucidate the effects of anthropogenic disturbance on ecological communities, with applications for conservation and restoration of species interactions and the ecosystem processes they maintain.
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Affiliation(s)
- Beth M L Morrison
- Department of Biology, Stanford University, Stanford, California, 94305, USA
| | - Rodolfo Dirzo
- Department of Biology, Stanford University, Stanford, California, 94305, USA
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5
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Torné‐Noguera A, Arnan X, Rodrigo A, Bosch J. Spatial variability of hosts, parasitoids and their interactions across a homogeneous landscape. Ecol Evol 2020; 10:3696-3705. [PMID: 32313628 PMCID: PMC7160165 DOI: 10.1002/ece3.6158] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2019] [Revised: 02/07/2020] [Accepted: 02/12/2020] [Indexed: 11/07/2022] Open
Abstract
Species assemblages and their interactions vary through space, generating diversity patterns at different spatial scales. Here, we study the local-scale spatial variation of a cavity-nesting bee and wasp community (hosts), their nest associates (parasitoids), and the resulting antagonistic network over a continuous and homogeneous habitat. To obtain bee/wasp nests, we placed trap-nests at 25 sites over a 32 km2 area. We obtained 1,541 nests (4,954 cells) belonging to 40 host species and containing 27 parasitoid species. The most abundant host species tended to have higher parasitism rate. Community composition dissimilarity was relatively high for both hosts and parasitoids, and the main component of this variability was species turnover, with a very minor contribution of ordered species loss (nestedness). That is, local species richness tended to be similar across the study area and community composition tended to differ between sites. Interestingly, the spatial matching between host and parasitoid composition was low. Host β-diversity was weakly (positively) but significantly related to geographic distance. On the other hand, parasitoid and host-parasitoid interaction β-diversities were not significantly related to geographic distance. Interaction β-diversity was even higher than host and parasitoid β-diversity, and mostly due to species turnover. Interaction rewiring between plots and between local webs and the regional metaweb was very low. In sum, species composition was rather idiosyncratic to each site causing a relevant mismatch between hosts and parasitoid composition. However, pairs of host and parasitoid species tended to interact similarly wherever they co-occurred. Our results additionally show that interaction β-diversity is better explained by parasitoid than by host β-diversity. We discuss the importance of identifying the sources of variation to understand the drivers of the observed heterogeneity.
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Affiliation(s)
| | | | - Anselm Rodrigo
- CREAFCerdanyola del VallèsSpain
- Universitat Autònoma de BarcelonaCerdanyola del VallèsSpain
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6
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Novella-Fernandez R, Rodrigo A, Arnan X, Bosch J. Interaction strength in plant-pollinator networks: Are we using the right measure? PLoS One 2019; 14:e0225930. [PMID: 31830077 PMCID: PMC6907754 DOI: 10.1371/journal.pone.0225930] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2019] [Accepted: 11/15/2019] [Indexed: 12/16/2022] Open
Abstract
Understanding how ecological networks are assembled is important because network structure reflects ecosystem functioning and stability. Quantitative network analysis incorporates measures of interaction strength as an estimate of the magnitude of the effect of interaction partners on one another. Most plant-pollinator network studies use frequency of interaction between individual pollinators and individual plants (encounter) as a surrogate of interaction strength. However, the number of flowers visited per encounter may strongly vary among pollinator and plant species, and therefore not all encounters are quantitatively equivalent. We sampled plant-pollinator interactions in a Mediterranean scrubland and tested whether using a measure of interaction strength based on the number of flowers visited resulted in changes in species (species strength, interaction species asymmetry, specialization) and network descriptors (nestedness, H2', interaction evenness, plant generality, pollinator generality) compared to the encounter-based measure. Several species (including some of the most abundant ones) showed important changes in species descriptors, notably in specialization. These changes were especially important in plant species with large floral displays, which became less specialized with the visit-based measure of interaction strength. At the network level we found significant changes in all properties analysed. With the encounter-based approach plant generality was much higher than pollinator generality (high specialization asymmetry between trophic levels). However, with the visit-based approach plant generality was greatly reduced so that plants and pollinators had similar levels of generalization. Interaction evenness also decreased strongly with the visit-based approach. We conclude that accounting for the number of flowers visited per encounter provides a more ecologically relevant measure of interaction strength. Our results have important implications for the stability of pollination networks and the evolution of plant-pollinator interactions. The use of a visit-based approach is especially important in studies relating interaction network structure and ecosystem function (pollination and/or exploitation of floral resources).
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Affiliation(s)
| | - Anselm Rodrigo
- Universitat Autònoma Barcelona, Cerdanyola del Vallès, Catalunya, Spain
- CREAF, Cerdanyola del Vallès, Catalunya, Spain
| | | | - Jordi Bosch
- CREAF, Cerdanyola del Vallès, Catalunya, Spain
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7
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Osorio-Canadas S, Arnan X, Bassols E, Vicens N, Bosch J. Seasonal dynamics in a cavity-nesting bee-wasp community: Shifts in composition, functional diversity and host-parasitoid network structure. PLoS One 2018; 13:e0205854. [PMID: 30325966 PMCID: PMC6191139 DOI: 10.1371/journal.pone.0205854] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2018] [Accepted: 10/02/2018] [Indexed: 11/19/2022] Open
Abstract
Ecological communities are composed of species that interact with each other forming complex interaction networks. Although interaction networks have been usually treated as static entities, interactions show high levels of temporal variation, mainly due to temporal species turnover. Changes in taxonomic composition are likely to bring about changes in functional trait composition. Because functional traits influence the likelihood that two species interact, temporal changes in functional composition and structure may ultimately affect interaction network structure. Here, we study the seasonality (spring vs. summer) in a community of cavity-nesting solitary bees and wasps (‘hosts’) and their nest associates (‘parasitoids’). We analyze seasonal changes in taxonomic compostion and structure, as well as in functional traits, of the host and parasitoid communities. We also analyze whether these changes result in changes in percent parasitism and interaction network structure. Our host and parasitoid communities are strongly seasonal. Host species richness increases from spring to summer. This results in important seasonal changes in functional composition of the host community. The spring community (almost exclusively composed of bees) is characterized by large, univoltine, adult-wintering host species. The summer community (composed of both bees and wasps) is dominated by smaller, bivoltine, prepupa-wintering species. Host functional diversity is higher in summer than in spring. Importantly, these functional changes are not only explained by the addition of wasp species in summer. Functional changes in the parasitoid community are much less pronounced, probably due to the lower parasitoid species turnover. Despite these important taxonomic and functional changes, levels of parasitism did not change across seasons. Two network metrics (generality and interaction evenness) increased from spring to summer. These changes can be explained by the seasonal increase in species richness (and therefore network size). The seasonal shift from a bee-dominated community in spring to a wasp-dominated community in summer suggests a change in ecosystem function, with emphasis on pollination in spring to emphasis on predation in summer.
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Affiliation(s)
| | | | - Emili Bassols
- Parc Natural de la Zona Volcànica de la Garrotxa, Olot, Spain
| | - Narcís Vicens
- Servei de Medi Ambient de la Diputació de Girona, Pujada Sant Martí 4–5, Girona, Spain
| | - Jordi Bosch
- CREAF, Cerdanyola del Vallès, Barcelona, Spain
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8
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Staab M, Pufal G, Tscharntke T, Klein A. Trap nests for bees and wasps to analyse trophic interactions in changing environments—A systematic overview and user guide. Methods Ecol Evol 2018. [DOI: 10.1111/2041-210x.13070] [Citation(s) in RCA: 44] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
Affiliation(s)
- Michael Staab
- Nature Conservation and Landscape EcologyFaculty of Environment and Natural ResourcesUniversity of Freiburg Freiburg Germany
- Freiburg Institute for Advanced Studies (FRIAS)University of Freiburg Freiburg Germany
| | - Gesine Pufal
- Nature Conservation and Landscape EcologyFaculty of Environment and Natural ResourcesUniversity of Freiburg Freiburg Germany
| | | | - Alexandra‐Maria Klein
- Nature Conservation and Landscape EcologyFaculty of Environment and Natural ResourcesUniversity of Freiburg Freiburg Germany
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9
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Pellissier L, Albouy C, Bascompte J, Farwig N, Graham C, Loreau M, Maglianesi MA, Melián CJ, Pitteloud C, Roslin T, Rohr R, Saavedra S, Thuiller W, Woodward G, Zimmermann NE, Gravel D. Comparing species interaction networks along environmental gradients. Biol Rev Camb Philos Soc 2017; 93:785-800. [PMID: 28941124 DOI: 10.1111/brv.12366] [Citation(s) in RCA: 105] [Impact Index Per Article: 15.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2017] [Revised: 08/17/2017] [Accepted: 08/18/2017] [Indexed: 12/25/2022]
Abstract
Knowledge of species composition and their interactions, in the form of interaction networks, is required to understand processes shaping their distribution over time and space. As such, comparing ecological networks along environmental gradients represents a promising new research avenue to understand the organization of life. Variation in the position and intensity of links within networks along environmental gradients may be driven by turnover in species composition, by variation in species abundances and by abiotic influences on species interactions. While investigating changes in species composition has a long tradition, so far only a limited number of studies have examined changes in species interactions between networks, often with differing approaches. Here, we review studies investigating variation in network structures along environmental gradients, highlighting how methodological decisions about standardization can influence their conclusions. Due to their complexity, variation among ecological networks is frequently studied using properties that summarize the distribution or topology of interactions such as number of links, connectance, or modularity. These properties can either be compared directly or using a procedure of standardization. While measures of network structure can be directly related to changes along environmental gradients, standardization is frequently used to facilitate interpretation of variation in network properties by controlling for some co-variables, or via null models. Null models allow comparing the deviation of empirical networks from random expectations and are expected to provide a more mechanistic understanding of the factors shaping ecological networks when they are coupled with functional traits. As an illustration, we compare approaches to quantify the role of trait matching in driving the structure of plant-hummingbird mutualistic networks, i.e. a direct comparison, standardized by null models and hypothesis-based metaweb. Overall, our analysis warns against a comparison of studies that rely on distinct forms of standardization, as they are likely to highlight different signals. Fostering a better understanding of the analytical tools available and the signal they detect will help produce deeper insights into how and why ecological networks vary along environmental gradients.
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Affiliation(s)
- Loïc Pellissier
- Landscape Ecology, Institute of Terrestrial Ecosystems, ETH Zürich, Zürich, Switzerland.,Swiss Federal Research Institute WSL, 8903, Birmensdorf, Switzerland
| | - Camille Albouy
- Landscape Ecology, Institute of Terrestrial Ecosystems, ETH Zürich, Zürich, Switzerland.,Swiss Federal Research Institute WSL, 8903, Birmensdorf, Switzerland.,IFREMER, unité Ecologie et Modèles pour l'Halieutique, rue de l'Ile d'Yeu, BP21105, 44311, Nantes cedex 3, France
| | - Jordi Bascompte
- Department of Evolutionary Biology and Environmental Studies, University of Zürich, 8057, Zürich, Switzerland
| | - Nina Farwig
- Conservation Ecology, Faculty of Biology, Philipps-Universität Marburg, Karl-von-Frisch-Str.8, D-35032, Marburg, Germany
| | - Catherine Graham
- Swiss Federal Research Institute WSL, 8903, Birmensdorf, Switzerland
| | - Michel Loreau
- Centre for Biodiversity Theory and Modelling, Theoretical and Experimental Ecology Station, CNRS and Paul Sabatier University, 09200, Moulis, France
| | - Maria Alejandra Maglianesi
- Vicerrectoría de Investigación, Universidad Estatal a Distancia, 2050, San José, Costa Rica.,Biodiversity and Climate Research Centre (BiK-F) and Senckenberg Gesellschaft für Naturforschung, 60325, Frankfurt am Main, Germany
| | - Carlos J Melián
- Department of Fish Ecology and Evolution, Eawag: Swiss Federal Institute of Aquatic Science and Technology, 6047, Kastanienbaum, Switzerland
| | - Camille Pitteloud
- Landscape Ecology, Institute of Terrestrial Ecosystems, ETH Zürich, Zürich, Switzerland.,Swiss Federal Research Institute WSL, 8903, Birmensdorf, Switzerland
| | - Tomas Roslin
- Department of Ecology, Swedish University of Agricultural Sciences, Uppsala, Sweden
| | - Rudolf Rohr
- Department of Biology - Ecology and Evolution, University of Fribourg, Fribourg, Switzerland
| | - Serguei Saavedra
- Department of Civil and Environmental Engineering, Massashusets Institute of Technology, 77 Massachusetts Avenue, Cambridge, 02139, MA, U.S.A
| | - Wilfried Thuiller
- University of Grenoble Alpes, CNRS, LECA (Laboratoire d'Écologie Alpine), F-38000, Grenoble, France
| | - Guy Woodward
- Department of Life Sciences, Imperial College London, Silwood Park Campus, Berkshire, SL5 7PY, U.K
| | - Niklaus E Zimmermann
- Landscape Ecology, Institute of Terrestrial Ecosystems, ETH Zürich, Zürich, Switzerland.,Swiss Federal Research Institute WSL, 8903, Birmensdorf, Switzerland
| | - Dominique Gravel
- Département de Biologie, Faculté des Sciences, Canada Research Chair in Integrative Ecology, Université de Sherbrooke, 2500, boulevard de l'Université, Sherbrooke, J1K 2R1, Québec, Canada
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