101
|
|
102
|
Guidi L, Chaffron S, Bittner L, Eveillard D, Larhlimi A, Roux S, Darzi Y, Audic S, Berline L, Brum J, Coelho LP, Espinoza JCI, Malviya S, Sunagawa S, Dimier C, Kandels-Lewis S, Picheral M, Poulain J, Searson S, Stemmann L, Not F, Hingamp P, Speich S, Follows M, Karp-Boss L, Boss E, Ogata H, Pesant S, Weissenbach J, Wincker P, Acinas SG, Bork P, de Vargas C, Iudicone D, Sullivan MB, Raes J, Karsenti E, Bowler C, Gorsky G. Plankton networks driving carbon export in the oligotrophic ocean. Nature 2016; 532:465-470. [PMID: 26863193 PMCID: PMC4851848 DOI: 10.1038/nature16942] [Citation(s) in RCA: 326] [Impact Index Per Article: 40.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2015] [Accepted: 12/18/2015] [Indexed: 01/02/2023]
Abstract
The biological carbon pump is the process by which CO2 is transformed to organic carbon via photosynthesis, exported through sinking particles, and finally sequestered in the deep ocean. While the intensity of the pump correlates with plankton community composition, the underlying ecosystem structure driving the process remains largely uncharacterised. Here we use environmental and metagenomic data gathered during the Tara Oceans expedition to improve our understanding of carbon export in the oligotrophic ocean. We show that specific plankton communities, from the surface and deep chlorophyll maximum, correlate with carbon export at 150 m and highlight unexpected taxa such as Radiolaria, alveolate parasites, as well as Synechococcus and their phages, as lineages most strongly associated with carbon export in the subtropical, nutrient-depleted, oligotrophic ocean. Additionally, we show that the relative abundance of just a few bacterial and viral genes can predict most of the variability in carbon export in these regions.
Collapse
Affiliation(s)
- Lionel Guidi
- Sorbonne Universités, UPMC Université Paris 06, CNRS, Laboratoire d'oceanographie de Villefranche (LOV), Observatoire Océanologique, Villefranche-sur-Mer, France.,Department of Oceanography, University of Hawaii, Honolulu, Hawaii, USA
| | - Samuel Chaffron
- Department of Microbiology and Immunology, Rega Institute, KU Leuven, Herestraat 49, 3000 Leuven, Belgium.,Center for the Biology of Disease, VIB, Herestraat 49, 3000 Leuven, Belgium.,Department of Applied Biological Sciences, Vrije Universiteit Brussel, Pleinlaan 2, 1050 Brussels, Belgium
| | - Lucie Bittner
- Sorbonne Universités, UPMC Univ Paris 06, CNRS, Institut de Biologie Paris-Seine (IBPS), Evolution Paris Seine, F-75005, Paris, France.,Ecole Normale Supérieure, PSL Research University, Institut de Biologie de l'Ecole Normale Supérieure (IBENS), CNRS UMR 8197, INSERM U1024, 46 rue d'Ulm, F-75005 Paris, France.,Sorbonne Universités, UPMC Université Paris 06, CNRS, Laboratoire Adaptation et Diversité en Milieu Marin, Station Biologique de Roscoff, Roscoff, France
| | - Damien Eveillard
- LINA UMR 6241, Université de Nantes, EMN, CNRS, 44322 Nantes, France
| | | | - Simon Roux
- Department of Ecology and Evolutionary Biology, University of Arizona, Tucson, AZ, 85721, USA
| | - Youssef Darzi
- Department of Microbiology and Immunology, Rega Institute, KU Leuven, Herestraat 49, 3000 Leuven, Belgium.,Center for the Biology of Disease, VIB, Herestraat 49, 3000 Leuven, Belgium
| | - Stephane Audic
- Sorbonne Universités, UPMC Université Paris 06, CNRS, Laboratoire Adaptation et Diversité en Milieu Marin, Station Biologique de Roscoff, Roscoff, France
| | - Léo Berline
- Sorbonne Universités, UPMC Université Paris 06, CNRS, Laboratoire d'oceanographie de Villefranche (LOV), Observatoire Océanologique, Villefranche-sur-Mer, France
| | - Jennifer Brum
- Department of Ecology and Evolutionary Biology, University of Arizona, Tucson, AZ, 85721, USA
| | - Luis Pedro Coelho
- Structural and Computational Biology, European Molecular Biology Laboratory, Meyerhofstr. 1, 69117 Heidelberg, Germany
| | | | - Shruti Malviya
- Ecole Normale Supérieure, PSL Research University, Institut de Biologie de l'Ecole Normale Supérieure (IBENS), CNRS UMR 8197, INSERM U1024, 46 rue d'Ulm, F-75005 Paris, France
| | - Shinichi Sunagawa
- Structural and Computational Biology, European Molecular Biology Laboratory, Meyerhofstr. 1, 69117 Heidelberg, Germany
| | - Céline Dimier
- Sorbonne Universités, UPMC Université Paris 06, CNRS, Laboratoire Adaptation et Diversité en Milieu Marin, Station Biologique de Roscoff, Roscoff, France
| | - Stefanie Kandels-Lewis
- Structural and Computational Biology, European Molecular Biology Laboratory, Meyerhofstr. 1, 69117 Heidelberg, Germany.,Directors' Research European Molecular Biology Laboratory Meyerhofstr. 1 69117 Heidelberg Germany
| | - Marc Picheral
- Sorbonne Universités, UPMC Université Paris 06, CNRS, Laboratoire d'oceanographie de Villefranche (LOV), Observatoire Océanologique, Villefranche-sur-Mer, France
| | - Julie Poulain
- CEA - Institut de Génomique, GENOSCOPE, 2 rue Gaston Crémieux, 91057 Evry France
| | - Sarah Searson
- Sorbonne Universités, UPMC Université Paris 06, CNRS, Laboratoire d'oceanographie de Villefranche (LOV), Observatoire Océanologique, Villefranche-sur-Mer, France.,Department of Oceanography, University of Hawaii, Honolulu, Hawaii, USA
| | | | - Lars Stemmann
- Sorbonne Universités, UPMC Université Paris 06, CNRS, Laboratoire d'oceanographie de Villefranche (LOV), Observatoire Océanologique, Villefranche-sur-Mer, France
| | - Fabrice Not
- Sorbonne Universités, UPMC Université Paris 06, CNRS, Laboratoire Adaptation et Diversité en Milieu Marin, Station Biologique de Roscoff, Roscoff, France
| | - Pascal Hingamp
- Aix Marseille Université CNRS IGS UMR 7256 13288 Marseille France
| | - Sabrina Speich
- Department of Geosciences, Laboratoire de Météorologie Dynamique (LMD), Ecole Normale Supérieure, 24 rue Lhomond 75231 Paris Cedex 05 France
| | - Mick Follows
- Dept of Earth, Atmospheric and Planetary Sciences, Massachusetts Institute of Technology, Cambridge, USA
| | - Lee Karp-Boss
- School of Marine Sciences, University of Maine, Orono, USA
| | - Emmanuel Boss
- School of Marine Sciences, University of Maine, Orono, USA
| | - Hiroyuki Ogata
- Institute for Chemical Research, Kyoto University, Gokasho, Uji, Kyoto, 611-0011, Japan
| | - Stephane Pesant
- PANGAEA, Data Publisher for Earth and Environmental Science, University of Bremen, Bremen, Germany.,MARUM, Center for Marine Environmental Sciences, University of Bremen, Bremen, Germany
| | - Jean Weissenbach
- CEA - Institut de Génomique, GENOSCOPE, 2 rue Gaston Crémieux, 91057 Evry France.,CNRS, UMR 8030, CP5706, Evry France.,Université d'Evry, UMR 8030, CP5706, Evry France
| | - Patrick Wincker
- CEA - Institut de Génomique, GENOSCOPE, 2 rue Gaston Crémieux, 91057 Evry France.,CNRS, UMR 8030, CP5706, Evry France.,Université d'Evry, UMR 8030, CP5706, Evry France
| | - Silvia G Acinas
- Department of Marine Biology and Oceanography, Institute of Marine Sciences (ICM)-CSIC Pg. Marítim de la Barceloneta 37-49 Barcelona E08003 Spain
| | - Peer Bork
- Structural and Computational Biology, European Molecular Biology Laboratory, Meyerhofstr. 1, 69117 Heidelberg, Germany.,Max-Delbrück-Centre for Molecular Medicine, 13092 Berlin, Germany
| | - Colomban de Vargas
- Sorbonne Universités, UPMC Université Paris 06, CNRS, Laboratoire Adaptation et Diversité en Milieu Marin, Station Biologique de Roscoff, Roscoff, France
| | - Daniele Iudicone
- Stazione Zoologica Anton Dohrn, Villa Comunale, 80121, Naples, Italy
| | - Matthew B Sullivan
- Department of Ecology and Evolutionary Biology, University of Arizona, Tucson, AZ, 85721, USA
| | - Jeroen Raes
- Department of Microbiology and Immunology, Rega Institute, KU Leuven, Herestraat 49, 3000 Leuven, Belgium.,Center for the Biology of Disease, VIB, Herestraat 49, 3000 Leuven, Belgium.,Department of Applied Biological Sciences, Vrije Universiteit Brussel, Pleinlaan 2, 1050 Brussels, Belgium
| | - Eric Karsenti
- Ecole Normale Supérieure, PSL Research University, Institut de Biologie de l'Ecole Normale Supérieure (IBENS), CNRS UMR 8197, INSERM U1024, 46 rue d'Ulm, F-75005 Paris, France.,Directors' Research European Molecular Biology Laboratory Meyerhofstr. 1 69117 Heidelberg Germany
| | - Chris Bowler
- Ecole Normale Supérieure, PSL Research University, Institut de Biologie de l'Ecole Normale Supérieure (IBENS), CNRS UMR 8197, INSERM U1024, 46 rue d'Ulm, F-75005 Paris, France
| | - Gabriel Gorsky
- Sorbonne Universités, UPMC Université Paris 06, CNRS, Laboratoire d'oceanographie de Villefranche (LOV), Observatoire Océanologique, Villefranche-sur-Mer, France
| |
Collapse
|
103
|
Abstract
In a cyber war game where a network is fully distributed and characterized by resource constraints and high dynamics, attackers or defenders often face a situation that may require optimal strategies to win the game with minimum effort. Given the system goal states of attackers and defenders, we study what strategies attackers or defenders can take to reach their respective system goal state (i.e., winning system state) with minimum resource consumption. However, due to the dynamics of a network caused by a node’s mobility, failure or its resource depletion over time or action(s), this optimization problem becomes NP-complete. We propose two heuristic strategies in a greedy manner based on a node’s two characteristics: resource level and influence based on k-hop reachability. We analyze complexity and optimality of each algorithm compared to optimal solutions for a small-scale static network. Further, we conduct a comprehensive experimental study for a large-scale temporal network to investigate best strategies, given a different environmental setting of network temporality and density. We demonstrate the performance of each strategy under various scenarios of attacker/defender strategies in terms of win probability, resource consumption, and system vulnerability.
Collapse
|
104
|
Colizzi ES, Hogeweg P. High cost enhances cooperation through the interplay between evolution and self-organisation. BMC Evol Biol 2016; 16:31. [PMID: 26832152 PMCID: PMC4736645 DOI: 10.1186/s12862-016-0600-9] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2015] [Accepted: 01/22/2016] [Indexed: 11/10/2022] Open
Abstract
Background Cooperation is ubiquitous in biological systems, yet its evolution is a long lasting evolutionary problem. A general and intuitive result from theoretical models of cooperative behaviour is that cooperation decreases when its costs are higher, because selfish individuals gain selective advantage. Results Contrary to this intuition, we show that cooperation can increase with higher costs. We analyse a minimal model where individuals live on a lattice and evolve the degree of cooperation. We find that a feedback establishes between the evolutionary dynamics of public good production and the spatial self-organisation of the population. The evolutionary dynamics lead to the speciation of a cooperative and a selfish lineage. The ensuing spatial self-organisation automatically diversifies the selection pressure on the two lineages. This enables selfish individuals to successfully invade cooperators at the expenses of their autonomous replication, and cooperators to increase public good production while expanding in the empty space left behind by cheaters. We show that this emergent feedback leads to higher degrees of cooperation when costs are higher. Conclusions An emergent feedback between evolution and self-organisation leads to high degrees of cooperation at high costs, under simple and general conditions. We propose this as a general explanation for the evolution of cooperative behaviours under seemingly prohibitive conditions. Electronic supplementary material The online version of this article (doi:10.1186/s12862-016-0600-9) contains supplementary material, which is available to authorized users.
Collapse
Affiliation(s)
- Enrico Sandro Colizzi
- Theoretical Biology, Utrecht University, Padualaan 8, Utrecht, 3524ZL, The Netherlands.
| | - Paulien Hogeweg
- Theoretical Biology, Utrecht University, Padualaan 8, Utrecht, 3524ZL, The Netherlands.
| |
Collapse
|
105
|
Sebastián-González E, Moleón M, Gibert JP, Botella F, Mateo-Tomás P, Olea PP, Guimarães PR, Sánchez-Zapata JA. Nested species-rich networks of scavenging vertebrates support high levels of interspecific competition. Ecology 2016; 97:95-105. [DOI: 10.1890/15-0212.1] [Citation(s) in RCA: 48] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Affiliation(s)
| | - Marcos Moleón
- Centre for African Ecology; School of Animal, Plant and Environmental Sciences; University of the Witwatersrand; Wits 2050 Johannesburg South Africa
- Departamento de Biología Aplicada; Universidad Miguel Hernández; Avda. de la Universidad, s/n 03202 Elche Alicante Spain
| | - Jean P. Gibert
- School of Biological Sciences; University of Nebraska-Lincoln; 410 Manter Hall Lincoln Nebraska 68588-0118 USA
| | - Francisco Botella
- Departamento de Biología Aplicada; Universidad Miguel Hernández; Avda. de la Universidad, s/n 03202 Elche Alicante Spain
| | - Patricia Mateo-Tomás
- Instituto de Investigación en Recursos Cinegéticos; IREC (CSIC-UCLM-JCCM); Ronda de Toledo s/n 17031 Ciudad Real Spain
| | - Pedro P. Olea
- Instituto de Investigación en Recursos Cinegéticos; IREC (CSIC-UCLM-JCCM); Ronda de Toledo s/n 17031 Ciudad Real Spain
- Departamento de Ecología; Universidad Autónoma de Madrid; 28046 Madrid Spain
| | - Paulo R. Guimarães
- Departamento de Ecologia; Universidade de São Paulo; CEP 05508 900 São Paulo Brazil
| | - José A. Sánchez-Zapata
- Departamento de Biología Aplicada; Universidad Miguel Hernández; Avda. de la Universidad, s/n 03202 Elche Alicante Spain
| |
Collapse
|
106
|
Suweis S, Grilli J, Banavar JR, Allesina S, Maritan A. Effect of localization on the stability of mutualistic ecological networks. Nat Commun 2015; 6:10179. [PMID: 26674106 PMCID: PMC4703855 DOI: 10.1038/ncomms10179] [Citation(s) in RCA: 58] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2015] [Accepted: 11/12/2015] [Indexed: 11/10/2022] Open
Abstract
The relationships between the core–periphery architecture of the species interaction network and the mechanisms ensuring the stability in mutualistic ecological communities are still unclear. In particular, most studies have focused their attention on asymptotic resilience or persistence, neglecting how perturbations propagate through the system. Here we develop a theoretical framework to evaluate the relationship between the architecture of the interaction networks and the impact of perturbations by studying localization, a measure describing the ability of the perturbation to propagate through the network. We show that mutualistic ecological communities are localized, and localization reduces perturbation propagation and attenuates its impact on species abundance. Localization depends on the topology of the interaction networks, and it positively correlates with the variance of the weighted degree distribution, a signature of the network topological heterogeneity. Our results provide a different perspective on the interplay between the architecture of interaction networks in mutualistic communities and their stability. The architecture of ecological interaction networks affects community dynamics. Here, Suweis et al. show that mutualistic networks are characterized by a high degree of localization, and that localization reduces perturbation propagation and attenuates its impact on species abundances.
Collapse
Affiliation(s)
- Samir Suweis
- Department of Physics and Astronomy, University of Padua, Consorzio Nazionale Interuniversitario per le Scienze Fisiche della Materia and Istituto Nazionale di Fisica Nucleare, 35131 Padova, Italy
| | - Jacopo Grilli
- Department of Ecology and Evolution, University of Chicago, 1101 East 57th Street, Chicago, Illinois 60637, USA
| | - Jayanth R Banavar
- Department of Physics, University of Maryland, College Park, Maryland 20742, USA
| | - Stefano Allesina
- Department of Ecology and Evolution, University of Chicago, 1101 East 57th Street, Chicago, Illinois 60637, USA
| | - Amos Maritan
- Department of Physics and Astronomy, University of Padua, Consorzio Nazionale Interuniversitario per le Scienze Fisiche della Materia and Istituto Nazionale di Fisica Nucleare, 35131 Padova, Italy
| |
Collapse
|
107
|
Multiple regimes of robust patterns between network structure and biodiversity. Sci Rep 2015; 5:17856. [PMID: 26632996 PMCID: PMC4668581 DOI: 10.1038/srep17856] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2015] [Accepted: 11/06/2015] [Indexed: 11/21/2022] Open
Abstract
Ecological networks such as plant-pollinator and host-parasite networks have structured interactions that define who interacts with whom. The structure of interactions also shapes ecological and evolutionary dynamics. Yet, there is significant ongoing debate as to whether certain structures, e.g., nestedness, contribute positively, negatively or not at all to biodiversity. We contend that examining variation in life history traits is key to disentangling the potential relationship between network structure and biodiversity. Here, we do so by analyzing a dynamic model of virus-bacteria interactions across a spectrum of network structures. Consistent with prior studies, we find plausible parameter domains exhibiting strong, positive relationships between nestedness and biodiversity. Yet, the same model can exhibit negative relationships between nestedness and biodiversity when examined in a distinct, plausible region of parameter space. We discuss steps towards identifying when network structure could, on its own, drive the resilience, sustainability, and even conservation of ecological communities.
Collapse
|
108
|
Saracco F, Di Clemente R, Gabrielli A, Pietronero L. From Innovation to Diversification: A Simple Competitive Model. PLoS One 2015; 10:e0140420. [PMID: 26544685 PMCID: PMC4636243 DOI: 10.1371/journal.pone.0140420] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2015] [Accepted: 09/25/2015] [Indexed: 11/30/2022] Open
Abstract
Few attempts have been proposed in order to describe the statistical features and historical evolution of the export bipartite matrix countries/products. An important standpoint is the introduction of a products network, namely a hierarchical forest of products that models the formation and the evolution of commodities. In the present article, we propose a simple dynamical model where countries compete with each other to acquire the ability to produce and export new products. Countries will have two possibilities to expand their export: innovating, i.e. introducing new goods, namely new nodes in the product networks, or copying the productive process of others, i.e. occupying a node already present in the same network. In this way, the topology of the products network and the country-product matrix evolve simultaneously, driven by the countries push toward innovation.
Collapse
Affiliation(s)
- Fabio Saracco
- Istituto dei Sistemi Complessi - ISC CNR UoS “Sapienza” Physics Department Università di Roma, P.le Aldo Moro 5, 00185, Rome, Italy
| | - Riccardo Di Clemente
- Istituto dei Sistemi Complessi - ISC CNR UoS “Sapienza” Physics Department Università di Roma, P.le Aldo Moro 5, 00185, Rome, Italy
| | - Andrea Gabrielli
- Istituto dei Sistemi Complessi - ISC CNR UoS “Sapienza” Physics Department Università di Roma, P.le Aldo Moro 5, 00185, Rome, Italy
- IMT Institute for Advanced Studies Lucca, Piazza S. Ponziano 6, 55100, Lucca, Italy
| | - Luciano Pietronero
- Sapienza, Università di Roma, Piazzale A. Moro 5, 00185, Rome, Italy
- London Institute for Mathematical Sciences, 35a South St, Mayfair, London, United Kingdom
| |
Collapse
|
109
|
Toju H, Guimarães PR, Olesen JM, Thompson JN. Below-ground plant-fungus network topology is not congruent with above-ground plant-animal network topology. SCIENCE ADVANCES 2015; 1:e1500291. [PMID: 26601279 PMCID: PMC4646793 DOI: 10.1126/sciadv.1500291] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/06/2015] [Accepted: 09/05/2015] [Indexed: 05/21/2023]
Abstract
In nature, plants and their pollinating and/or seed-dispersing animals form complex interaction networks. The commonly observed pattern of links between specialists and generalists in these networks has been predicted to promote species coexistence. Plants also build highly species-rich mutualistic networks below ground with root-associated fungi, and the structure of these plant-fungus networks may also affect terrestrial community processes. By compiling high-throughput DNA sequencing data sets of the symbiosis of plants and their root-associated fungi from three localities along a latitudinal gradient, we uncovered the entire network architecture of these interactions under contrasting environmental conditions. Each network included more than 30 plant species and hundreds of mycorrhizal and endophytic fungi belonging to diverse phylogenetic groups. The results were consistent with the notion that processes shaping host-plant specialization of fungal species generate a unique linkage pattern that strongly contrasts with the pattern of above-ground plant-partner networks. Specifically, plant-fungus networks lacked a "nested" architecture, which has been considered to promote species coexistence in plant-partner networks. Rather, the below-ground networks had a conspicuous "antinested" topology. Our findings lead to the working hypothesis that terrestrial plant community dynamics are likely determined by the balance between above-ground and below-ground webs of interspecific interactions.
Collapse
Affiliation(s)
- Hirokazu Toju
- Graduate School of Human and Environmental Studies, Kyoto University, Sakyo, Kyoto 606-8501, Japan
| | - Paulo R. Guimarães
- Departamento de Ecologia, Instituto de Biociências, Universidade de São Paulo, São Paulo 05508-900, São Paulo, Brazil
| | - Jens M. Olesen
- Department of Bioscience, Aarhus University, Ny Munkegade 114, 8000 Aarhus C, Denmark
| | - John N. Thompson
- Department of Ecology and Evolutionary Biology, University of California, Santa Cruz, CA 95064, USA
| |
Collapse
|
110
|
Gilljam D, Curtsdotter A, Ebenman B. Adaptive rewiring aggravates the effects of species loss in ecosystems. Nat Commun 2015; 6:8412. [DOI: 10.1038/ncomms9412] [Citation(s) in RCA: 54] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2015] [Accepted: 08/19/2015] [Indexed: 11/09/2022] Open
|
111
|
|
112
|
Dwivedi SK, Jalan S. Interplay of mutation and disassortativity. PHYSICAL REVIEW. E, STATISTICAL, NONLINEAR, AND SOFT MATTER PHYSICS 2015; 92:022802. [PMID: 26382449 DOI: 10.1103/physreve.92.022802] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/09/2015] [Indexed: 06/05/2023]
Abstract
Despite disassortativity being commonly observed in many biological networks, our current understanding of its evolutionary origin is inadequate. Motivated by the occurrence of mutations during an evolutionary time span that results in changes in the behavior of interactions, we demonstrate that if we maximize the stability of the underlying system, the genetic algorithm leads to the evolution of a disassortative structure. The mutation probability governs the degree of saturation of the disassortativity coefficient, and this reveals the origin of the wide range of disassortativity values found in real systems. We analytically verify these results for star networks, and by considering various values for the antisymmetric couplings, we find a regime in which scale-free networks are more stable than the corresponding random networks.
Collapse
Affiliation(s)
- Sanjiv K Dwivedi
- Complex Systems Lab, Discipline of Physics, Indian Institute of Technology Indore, Indore 452017, India
| | - Sarika Jalan
- Complex Systems Lab, Discipline of Physics, Indian Institute of Technology Indore, Indore 452017, India
- Centre for Biosciences and Biomedical Engineering, Indian Institute of Technology Indore, Indore 452017, India
| |
Collapse
|
113
|
Nitzan M, Mintzer S, Margalit H. Approaches and developments in studying the human microbiome network. Isr J Ecol Evol 2015. [DOI: 10.1080/15659801.2015.1042768] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
The human microbiome is dynamic and unique to each individual, and its role is being increasingly recognized in healthy physiology and in disease, including gastrointestinal and neuropsychiatric disorders. Therefore, characterizing the human microbiome and the factors that shape its bacterial population, how they are related to host-specific attributes, and understanding the ways in which it can be manipulated and the phenotypic consequences of such manipulations are of great importance. Characterization of the microbiome so far has been mostly based on compositional studies alone, where relative abundances of different species are compared in different conditions, such as health and disease. However, inter-relationships among the bacterial species, such as competition and cooperation over metabolic resources, may be an important factor that affects the structure and function of the microbiome. Here we review the network-based approaches in answering such questions and explore the first attempts that focus on the interactions facet, complementing compositional studies, towards understanding the microbiome structure and its complex relationship with the human host.
Collapse
Affiliation(s)
- Mor Nitzan
- Racah Institute of Physics, Hebrew University of Jerusalem
- Department of Microbiology and Molecular Genetics, IMRIC, Faculty of Medicine, Hebrew University of Jerusalem
| | - Sefi Mintzer
- Department of Microbiology and Molecular Genetics, IMRIC, Faculty of Medicine, Hebrew University of Jerusalem
| | - Hanah Margalit
- Department of Microbiology and Molecular Genetics, IMRIC, Faculty of Medicine, Hebrew University of Jerusalem
| |
Collapse
|
114
|
Carrara F, Giometto A, Seymour M, Rinaldo A, Altermatt F. Experimental evidence for strong stabilizing forces at high functional diversity of aquatic microbial communities. Ecology 2015; 96:1340-50. [DOI: 10.1890/14-1324.1] [Citation(s) in RCA: 36] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
|
115
|
Benítez-Malvido J, Dáttilo W. Interaction intimacy of pathogens and herbivores with their host plants influences the topological structure of ecological networks in different ways. AMERICAN JOURNAL OF BOTANY 2015; 102:512-519. [PMID: 25878085 DOI: 10.3732/ajb.1400303] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/02/2014] [Accepted: 03/04/2015] [Indexed: 06/04/2023]
Abstract
UNLABELLED • PREMISE OF THE STUDY Over the past two decades an interest in the role that plant-animal mutualistic networks play in the organization and dynamic of biodiversity has steadily risen. Despite the ecological, evolutionary, and economic importance of plant-herbivore and plant-pathogen antagonistic relationships, however, few studies have examined these interactions in an ecological network framework.• METHODS We describe for the first time the topological structure of multitrophic networks involving congeneric tropical plant species of the genus Heliconia (Heliconiaceae, Zingiberales) and their herbivores and pathogens in the state of Pernambuco, Brazil. We based our study on the available literature describing the organisms (e.g., insects, mites, fungi, and bacteria) that attack 24 different species, hybrids, and cultivated varieties of Heliconia.• KEY RESULTS In general, pathogen- and herbivore-Heliconia networks differed in their topological structure (more modular vs. more nested, respectively): pathogen-Heliconia networks were more specialized and compartmentalized than herbivore-Heliconia networks. High modularity was likely due to the high intimacy that pathogens have with their host plants as compared with the more generalized feeding modes and behavior of herbivores. Some clusters clearly reflected the clustering of closely related cultivated varieties of Heliconia sharing the same pathogens.• CONCLUSIONS From a commercial standpoint, different varieties of the same Heliconia species may be more susceptible to being attacked by the same species of pathogens. In summary, our study highlights the importance of interaction intimacy in structuring trophic relationships between plants and pathogens in the tropics.
Collapse
Affiliation(s)
- Julieta Benítez-Malvido
- Centro de Investigaciones en Ecosistemas, Universidad Nacional Autónoma de México (UNAM), Antigua Carretera a Pátzcuaro No. 8701, Ex Hacienda de San José de la Huerta 58190 Morelia, Michoacán, Mexico
| | - Wesley Dáttilo
- Instituto de Neuroetología, Universidad Veracruzana, Av. Dr. Luis Castelazo s/n 91190 Xalapa, Veracruz, Mexico
| |
Collapse
|
116
|
Quinto J, Marcos-García MDLÁ, Díaz-Castelazo C, Rico-Gray V, Galante E, Micó E. Association patterns in saproxylic insect networks in three Iberian Mediterranean woodlands and their resistance to microhabitat loss. PLoS One 2015; 10:e0122141. [PMID: 25811197 PMCID: PMC4374943 DOI: 10.1371/journal.pone.0122141] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2014] [Accepted: 02/16/2015] [Indexed: 11/18/2022] Open
Abstract
The assessment of the relationship between species diversity, species interactions and environmental characteristics is indispensable for understanding network architecture and ecological distribution in complex networks. Saproxylic insect communities inhabiting tree hollow microhabitats within Mediterranean woodlands are highly dependent on woodland configuration and on microhabitat supply they harbor, so can be studied under the network analysis perspective. We assessed the differences in interacting patterns according to woodland site, and analysed the importance of functional species in modelling network architecture. We then evaluated their implications for saproxylic assemblages' persistence, through simulations of three possible scenarios of loss of tree hollow microhabitat. Tree hollow-saproxylic insect networks per woodland site presented a significant nested pattern. Those woodlands with higher complexity of tree individuals and tree hollow microhabitats also housed higher species/interactions diversity and complexity of saproxylic networks, and exhibited a higher degree of nestedness, suggesting that a higher woodland complexity positively influences saproxylic diversity and interaction complexity, thus determining higher degree of nestedness. Moreover, the number of insects acting as key interconnectors (nodes falling into the core region, using core/periphery tests) was similar among woodland sites, but the species identity varied on each. Such differences in insect core composition among woodland sites suggest the functional role they depict at woodland scale. Tree hollows acting as core corresponded with large tree hollows near the ground and simultaneously housing various breeding microsites, whereas core insects were species mediating relevant ecological interactions within saproxylic communities, e.g. predation, competitive or facilitation interactions. Differences in network patterns and tree hollow characteristics among woodland sites clearly defined different sensitivity to microhabitat loss, and higher saproxylic diversity and woodland complexity showed positive relation with robustness. These results highlight that woodland complexity goes hand in hand with biotic and ecological complexity of saproxylic networks, and together exhibited positive effects on network robustness.
Collapse
Affiliation(s)
- Javier Quinto
- Centro Iberoamericano de la Biodiversidad (CIBIO), Universidad de Alicante, Alicante, Spain
| | | | | | | | - Eduardo Galante
- Centro Iberoamericano de la Biodiversidad (CIBIO), Universidad de Alicante, Alicante, Spain
| | - Estefanía Micó
- Centro Iberoamericano de la Biodiversidad (CIBIO), Universidad de Alicante, Alicante, Spain
| |
Collapse
|
117
|
Abstract
SUMMARYHosts and parasites interact with each other in a variety of ways, and this diversity of interactions is reflected in the networks they form. To test for differences in interaction patterns of ecto- and endoparasites we analysed subnetworks formed by each kind of parasites and their host fish species in fish–parasite networks for 22 localities. We assessed the proportion of parasite species per host species, the relationship between parasite fauna composition and host taxonomy, connectance, nestedness and modularity of each subnetwork (n = 44). Furthermore, we evaluated the similarity in host species composition among modules in ecto- and endoparasite subnetworks. We found several differences between subnetworks of fish ecto- and endoparasites. The association with a higher number of host species observed among endoparasites resulted in higher connectance and nestedness, and lower values of modularity in their subnetworks than in those of ectoparasites. Taxonomically related host species tended to share ecto- or endoparasites with the same interaction intensity, but the species composition of hosts tended to differ between modules formed by ecto- and endoparasites. Our results suggest that different evolutionary and ecological processes are responsible for organizing the networks formed by ecto- and endoparasites and fish.
Collapse
|
118
|
Bird-flower visitation networks in the Galápagos unveil a widespread interaction release. Nat Commun 2015; 6:6376. [PMID: 25757227 DOI: 10.1038/ncomms7376] [Citation(s) in RCA: 48] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2014] [Accepted: 01/23/2015] [Indexed: 11/08/2022] Open
Abstract
Owing to food scarcity and to the high densities that vertebrates often reach on islands, typical insect- and seed-eaters widen their feeding niche and interact with a greater fraction of species than their mainland counterparts. This phenomenon, coined here 'interaction release', has been previously reported for single species but never for an entire community. During 4 years, we gathered data on bird-flower visitation on 12 Galápagos islands. We show that all sampled land birds exploit floral resources and act as potential pollinators across the entire archipelago, in all major habitats and all year round. Although species and link composition varies among islands, strong interaction release takes place on all islands, making their bird-flower network highly generalized. Interaction release is crucial to the survival of native birds but simultaneously threatens the unique biodiversity of this archipelago, as the birds also visit invading plants, likely facilitating their integration into pristine native communities.
Collapse
|
119
|
Cristelli M, Tacchella A, Pietronero L. The heterogeneous dynamics of economic complexity. PLoS One 2015; 10:e0117174. [PMID: 25671312 PMCID: PMC4325004 DOI: 10.1371/journal.pone.0117174] [Citation(s) in RCA: 123] [Impact Index Per Article: 13.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2014] [Accepted: 12/19/2014] [Indexed: 11/30/2022] Open
Abstract
What will be the growth of the Gross Domestic Product (GDP) or the competitiveness of China, United States, and Vietnam in the next 3, 5 or 10 years? Despite this kind of questions has a large societal impact and an extreme value for economic policy making, providing a scientific basis for economic predictability is still a very challenging problem. Recent results of a new branch—Economic Complexity—have set the basis for a framework to approach such a challenge and to provide new perspectives to cast economic prediction into the conceptual scheme of forecasting the evolution of a dynamical system as in the case of weather dynamics. We argue that a recently introduced non-monetary metrics for country competitiveness (fitness) allows for quantifying the hidden growth potential of countries by the means of the comparison of this measure for intangible assets with monetary figures, such as GDP per capita. This comparison defines the fitness-income plane where we observe that country dynamics presents strongly heterogeneous patterns of evolution. The flow in some zones is found to be laminar while in others a chaotic behavior is instead observed. These two regimes correspond to very different predictability features for the evolution of countries: in the former regime, we find strong predictable pattern while the latter scenario exhibits a very low predictability. In such a framework, regressions, the usual tool used in economics, are no more the appropriate strategy to deal with such a heterogeneous scenario and new concepts, borrowed from dynamical systems theory, are mandatory. We therefore propose a data-driven method—the selective predictability scheme—in which we adopt a strategy similar to the methods of analogues, firstly introduced by Lorenz, to assess future evolution of countries.
Collapse
Affiliation(s)
- Matthieu Cristelli
- ISC-CNR, Institute for Complex Systems, Rome, Italy
- Physics Department, Sapienza University of Rome, Rome, Italy
- * E-mail:
| | - Andrea Tacchella
- ISC-CNR, Institute for Complex Systems, Rome, Italy
- Physics Department, Sapienza University of Rome, Rome, Italy
| | - Luciano Pietronero
- ISC-CNR, Institute for Complex Systems, Rome, Italy
- Physics Department, Sapienza University of Rome, Rome, Italy
- London Institute for Mathematical Sciences, London, United Kingdom
| |
Collapse
|
120
|
|
121
|
Astegiano J, Guimarães PR, Cheptou PO, Vidal MM, Mandai CY, Ashworth L, Massol F. Persistence of Plants and Pollinators in the Face of Habitat Loss. ADV ECOL RES 2015. [DOI: 10.1016/bs.aecr.2015.09.005] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
|
122
|
Welti EAR, Joern A. Structure of trophic and mutualistic networks across broad environmental gradients. Ecol Evol 2014; 5:326-34. [PMID: 25691960 PMCID: PMC4314265 DOI: 10.1002/ece3.1371] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2014] [Revised: 11/14/2014] [Accepted: 11/25/2014] [Indexed: 11/17/2022] Open
Abstract
This study aims to understand how inherent ecological network structures of nestedness and modularity vary over large geographic scales with implications for community stability. Bipartite networks from previous research from 68 locations globally were analyzed. Using a meta-analysis approach, we examine relationships between the structure of 22 trophic and 46 mutualistic bipartite networks in response to extensive gradients of temperature and precipitation. Network structures varied significantly across temperature gradients. Trophic networks showed decreasing modularity with increasing variation in temperature within years. Nestedness of mutualistic networks decreased with increasing temperature variability between years. Mean annual precipitation and variability of precipitation were not found to have significant influence on the structure of either trophic or mutualistic networks. By examining changes in ecological networks across large-scale abiotic gradients, this study identifies temperature variability as a potential environmental mediator of community stability. Understanding these relationships contributes to our ability to predict responses of biodiversity to climate change at the community level.
Collapse
Affiliation(s)
- Ellen A R Welti
- Division of Biology, Kansas State University 116 Ackert Hall, Manhattan, Kansas, 66506-4901
| | - Anthony Joern
- Division of Biology, Kansas State University 116 Ackert Hall, Manhattan, Kansas, 66506-4901
| |
Collapse
|
123
|
Campbell C, Yang S, Albert R, Shea K. Plant-pollinator community network response to species invasion depends on both invader and community characteristics. OIKOS 2014. [DOI: 10.1111/oik.02039] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
Affiliation(s)
- Colin Campbell
- Dept of Biology; Pennsylvania State Univ.; 208 Mueller Laboratory University Park PA 16802 USA
- Dept of Physics; Pennsylvania State Univ.; 122 Davey Laboratory University Park PA 16802 USA
| | - Suann Yang
- Biology Department; Presbyterian College; Clinton SC 29325 USA
| | - Réka Albert
- Dept of Biology; Pennsylvania State Univ.; 208 Mueller Laboratory University Park PA 16802 USA
- Dept of Physics; Pennsylvania State Univ.; 122 Davey Laboratory University Park PA 16802 USA
| | - Katriona Shea
- Dept of Biology; Pennsylvania State Univ.; 208 Mueller Laboratory University Park PA 16802 USA
| |
Collapse
|
124
|
Stouffer DB, Cirtwill AR, Bascompte J, Bartomeus I. How exotic plants integrate into pollination networks. THE JOURNAL OF ECOLOGY 2014; 102:1442-1450. [PMID: 25558089 PMCID: PMC4277853 DOI: 10.1111/1365-2745.12310] [Citation(s) in RCA: 40] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/09/2014] [Accepted: 08/05/2014] [Indexed: 05/23/2023]
Abstract
There is increasing world-wide concern about the impact of the introduction of exotic species on ecological communities. Since many exotic plants depend on native pollinators to successfully establish, it is of paramount importance that we understand precisely how exotic species integrate into existing plant-pollinator communities. In this manuscript, we have studied a global data base of empirical pollination networks to determine whether community, network, species or interaction characteristics can help identify invaded communities. We found that a limited number of community and network properties showed significant differences across the empirical data sets - namely networks with exotic plants present are characterized by greater total, plant and pollinator richness, as well as higher values of relative nestedness.We also observed significant differences in terms of the pollinators that interact with the exotic plants. In particular, we found that specialist pollinators that are also weak contributors to community nestedness are far more likely to interact with exotic plants than would be expected by chance alone.Synthesis. By virtue of their interactions, it appears that exotic plants may provide a key service to a community's specialist pollinators as well as fill otherwise vacant 'coevolutionary niches'.
Collapse
Affiliation(s)
- Daniel B Stouffer
- School of Biological Sciences, University of Canterbury, Private Bag 4800Christchurch, 8140, New Zealand
- Integrative Ecology Group, Estación Biológica de Doñana (EBD-CSIC)c/ Américo Vespucio s/n, 41092, Sevilla, Spain
- *Correspondence author. E-mail:
| | - Alyssa R Cirtwill
- School of Biological Sciences, University of Canterbury, Private Bag 4800Christchurch, 8140, New Zealand
| | - Jordi Bascompte
- Integrative Ecology Group, Estación Biológica de Doñana (EBD-CSIC)c/ Américo Vespucio s/n, 41092, Sevilla, Spain
| | | |
Collapse
|
125
|
Toju H, Guimarães PR, Olesen JM, Thompson JN. Assembly of complex plant-fungus networks. Nat Commun 2014; 5:5273. [PMID: 25327887 PMCID: PMC4218951 DOI: 10.1038/ncomms6273] [Citation(s) in RCA: 119] [Impact Index Per Article: 11.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2014] [Accepted: 09/16/2014] [Indexed: 02/03/2023] Open
Abstract
Species in ecological communities build complex webs of interaction. Although revealing the architecture of these networks is fundamental to understanding ecological and evolutionary dynamics in nature, it has been difficult to characterize the structure of most species-rich ecological systems. By overcoming this limitation through next-generation sequencing technology, we herein uncover the network architecture of below-ground plant-fungus symbioses, which are ubiquitous to terrestrial ecosystems. The examined symbiotic network of a temperate forest in Japan includes 33 plant species and 387 functionally and phylogenetically diverse fungal taxa, and the overall network architecture differs fundamentally from that of other ecological networks. In contrast to results for other ecological networks and theoretical predictions for symbiotic networks, the plant-fungus network shows moderate or relatively low levels of interaction specialization and modularity and an unusual pattern of 'nested' network architecture. These results suggest that species-rich ecological networks are more architecturally diverse than previously recognized.
Collapse
Affiliation(s)
- Hirokazu Toju
- Graduate School of Human and Environmental Studies, Kyoto University, Sakyo, Kyoto 606-8501, Japan
| | - Paulo R. Guimarães
- Departamento de Ecologia, Instituto de Biociências, Universidade de São Paulo, São Paulo 05508-900, Brazil
| | - Jens M. Olesen
- Department of Bioscience, Aarhus University, Ny Munkegade 114, 8000 Aarhus C, Denmark
| | - John N. Thompson
- Department of Ecology and Evolutionary Biology, University of California, Santa Cruz, California 95064, USA
| |
Collapse
|
126
|
Widder S, Besemer K, Singer GA, Ceola S, Bertuzzo E, Quince C, Sloan WT, Rinaldo A, Battin TJ. Fluvial network organization imprints on microbial co-occurrence networks. Proc Natl Acad Sci U S A 2014; 111:12799-804. [PMID: 25136087 PMCID: PMC4156742 DOI: 10.1073/pnas.1411723111] [Citation(s) in RCA: 125] [Impact Index Per Article: 12.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
Recent studies highlight linkages among the architecture of ecological networks, their persistence facing environmental disturbance, and the related patterns of biodiversity. A hitherto unresolved question is whether the structure of the landscape inhabited by organisms leaves an imprint on their ecological networks. We analyzed, based on pyrosequencing profiling of the biofilm communities in 114 streams, how features inherent to fluvial networks affect the co-occurrence networks that the microorganisms form in these biofilms. Our findings suggest that hydrology and metacommunity dynamics, both changing predictably across fluvial networks, affect the fragmentation of the microbial co-occurrence networks throughout the fluvial network. The loss of taxa from co-occurrence networks demonstrates that the removal of gatekeepers disproportionately contributed to network fragmentation, which has potential implications for the functions biofilms fulfill in stream ecosystems. Our findings are critical because of increased anthropogenic pressures deteriorating stream ecosystem integrity and biodiversity.
Collapse
Affiliation(s)
- Stefanie Widder
- Division of Computational Systems Biology, Department of Microbiology and Ecosystem Science, University of Vienna, A-1090 Vienna, Austria
| | - Katharina Besemer
- Division of Limnology, Department of Limnology and Oceanography, University of Vienna, A-1090 Vienna, Austria; WasserCluster Lunz GmbH, A-3293 Lunz am See, Austria
| | - Gabriel A Singer
- Division of Limnology, Department of Limnology and Oceanography, University of Vienna, A-1090 Vienna, Austria; Leibniz-Institute of Freshwater Ecology and Inland Fisheries, D-12587 Berlin, Germany
| | - Serena Ceola
- Dipartimento di Ingegneria Civile, Chimica, Ambientale e dei Materiali, Università di Bologna, I-40136 Bologna, Italy
| | - Enrico Bertuzzo
- Laboratory of Ecohydrology, School of Architecture, Ecole Polytechnique Fédérale de Lausanne, CH-1015 Lausanne, Switzerland
| | - Christopher Quince
- School of Engineering, University of Glasgow, Glasgow G12 8QQ, United Kingdom; and
| | - William T Sloan
- School of Engineering, University of Glasgow, Glasgow G12 8QQ, United Kingdom; and
| | - Andrea Rinaldo
- Laboratory of Ecohydrology, School of Architecture, Ecole Polytechnique Fédérale de Lausanne, CH-1015 Lausanne, Switzerland; Dipartimento di Ingegneria Civile, Edile e Ambientale, Università di Padova, I-35131 Padova, Italy
| | - Tom J Battin
- Division of Limnology, Department of Limnology and Oceanography, University of Vienna, A-1090 Vienna, Austria; WasserCluster Lunz GmbH, A-3293 Lunz am See, Austria;
| |
Collapse
|
127
|
García-Algarra J, Galeano J, Pastor JM, Iriondo JM, Ramasco JJ. Rethinking the logistic approach for population dynamics of mutualistic interactions. J Theor Biol 2014; 363:332-43. [PMID: 25173080 DOI: 10.1016/j.jtbi.2014.08.039] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2014] [Revised: 07/18/2014] [Accepted: 08/20/2014] [Indexed: 10/24/2022]
Abstract
Mutualistic communities have an internal structure that makes them resilient to external perturbations. Late research has focused on their stability and the topology of the relations between the different organisms to explain the reasons of the system robustness. Much less attention has been invested in analyzing the systems dynamics. The main population models in use are modifications of the r-K formulation of logistic equation with additional terms to account for the benefits produced by the interspecific interactions. These models have shortcomings as the so-called r-K formulation diverges under some conditions. In this work, we introduce a model for population dynamics under mutualism that preserves the original logistic formulation. It is mathematically simpler than the widely used type II models, although it shows similar complexity in terms of fixed points and stability of the dynamics. We perform an analytical stability analysis and numerical simulations to study the model behavior in general interaction scenarios including tests of the resilience of its dynamics under external perturbations. Despite its simplicity, our results indicate that the model dynamics shows an important richness that can be used to gain further insights in the dynamics of mutualistic communities.
Collapse
Affiliation(s)
| | - Javier Galeano
- Complex System Group, Universidad Politécnica de Madrid, 28040 Madrid, Spain; Dep. Ciencia y Tecnología Aplicadas a la I.T. Agrícola, E.U.I.T. Agrícola, Universidad Politécnica de Madrid, 28040 Madrid, Spain.
| | - Juan Manuel Pastor
- Complex System Group, Universidad Politécnica de Madrid, 28040 Madrid, Spain; Dep. Ciencia y Tecnología Aplicadas a la I.T. Agrícola, E.U.I.T. Agrícola, Universidad Politécnica de Madrid, 28040 Madrid, Spain
| | - José María Iriondo
- Área de Biodiversidad y Conservación, Dept. Biología y Geología, Universidad Rey Juan Carlos, 28933 Móstoles, Spain
| | - José J Ramasco
- Instituto de Física Interdisciplinar y Sistemas Complejos IFISC (CSIC-UIB), Campus UIB, 07122 Palma de Mallorca, Spain
| |
Collapse
|
128
|
Affiliation(s)
- Samraat Pawar
- Department of Life Sciences, Imperial College London, Silwood Park, Ascot, Berkshire SL5 7PY, U K.
| |
Collapse
|
129
|
Rohr RP, Saavedra S, Bascompte J. Ecological networks. On the structural stability of mutualistic systems. Science 2014; 345:1253497. [PMID: 25061214 DOI: 10.1126/science.1253497] [Citation(s) in RCA: 274] [Impact Index Per Article: 27.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
In theoretical ecology, traditional studies based on dynamical stability and numerical simulations have not found a unified answer to the effect of network architecture on community persistence. Here, we introduce a mathematical framework based on the concept of structural stability to explain such a disparity of results. We investigated the range of conditions necessary for the stable coexistence of all species in mutualistic systems. We show that the apparently contradictory conclusions reached by previous studies arise as a consequence of overseeing either the necessary conditions for persistence or its dependence on model parameterization. We show that observed network architectures maximize the range of conditions for species coexistence. We discuss the applicability of structural stability to study other types of interspecific interactions.
Collapse
Affiliation(s)
- Rudolf P Rohr
- Integrative Ecology Group, Estación Biológica de Doñana-Consejo Superior de Investigaciones Científicas (EBD-CSIC), Calle Américo Vespucio s/n, E-41092 Sevilla, Spain. Unit of Ecology and Evolution, Department of Biology, University of Fribourg, Chemin du Musée 10, CH-1700 Fribourg, Switzerland
| | - Serguei Saavedra
- Integrative Ecology Group, Estación Biológica de Doñana-Consejo Superior de Investigaciones Científicas (EBD-CSIC), Calle Américo Vespucio s/n, E-41092 Sevilla, Spain
| | - Jordi Bascompte
- Integrative Ecology Group, Estación Biológica de Doñana-Consejo Superior de Investigaciones Científicas (EBD-CSIC), Calle Américo Vespucio s/n, E-41092 Sevilla, Spain.
| |
Collapse
|
130
|
Heterogeneity in ecological mutualistic networks dominantly determines community stability. Sci Rep 2014; 4:5912. [PMID: 25081499 PMCID: PMC4118322 DOI: 10.1038/srep05912] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2014] [Accepted: 07/04/2014] [Indexed: 12/04/2022] Open
Abstract
Although the hypothesis that nestedness determines mutualistic ecosystem dynamics is accepted in general, results of some recent data analyses and theoretical studies have begun to cast doubt on the impact of nestedness on ecosystem stability. However, definite conclusions have not yet been reached because previous studies are mainly based on numerical simulations. Therefore, we reveal a mathematical architecture in the relationship between ecological mutualistic networks and local stability based on spectral graph analysis. In particular, we propose a theoretical method for estimating the dominant eigenvalue (i.e., spectral radius) of quantitative (or weighted) bipartite networks by extending spectral graph theory, and provide a theoretical prediction that the heterogeneity of node degrees and link weights primarily determines the local stability; on the other hand, nestedness additionally affects it. Numerical simulations demonstrate the validity of our theory and prediction. This study emphasizes the importance of ecological network heterogeneity in ecosystem dynamics, and it enhances our understanding of structure–stability relationships.
Collapse
|
131
|
Suweis S, D'Odorico P. Early warning signs in social-ecological networks. PLoS One 2014; 9:e101851. [PMID: 25013901 PMCID: PMC4094384 DOI: 10.1371/journal.pone.0101851] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2014] [Accepted: 06/11/2014] [Indexed: 11/28/2022] Open
Abstract
A number of social-ecological systems exhibit complex behaviour associated with nonlinearities, bifurcations, and interaction with stochastic drivers. These systems are often prone to abrupt and unexpected instabilities and state shifts that emerge as a discontinuous response to gradual changes in environmental drivers. Predicting such behaviours is crucial to the prevention of or preparation for unwanted regime shifts. Recent research in ecology has investigated early warning signs that anticipate the divergence of univariate ecosystem dynamics from a stable attractor. To date, leading indicators of instability in systems with multiple interacting components have remained poorly investigated. This is a major limitation in the understanding of the dynamics of complex social-ecological networks. Here, we develop a theoretical framework to demonstrate that rising variance—measured, for example, by the maximum element of the covariance matrix of the network—is an effective leading indicator of network instability. We show that its reliability and robustness depend more on the sign of the interactions within the network than the network structure or noise intensity. Mutualistic, scale free and small world networks are less stable than their antagonistic or random counterparts but their instability is more reliably predicted by this leading indicator. These results provide new advances in multidimensional early warning analysis and offer a framework to evaluate the resilience of social-ecological networks.
Collapse
Affiliation(s)
- Samir Suweis
- Physics Department, University of Padua, Padova, Italy
| | - Paolo D'Odorico
- Department of Environmental Sciences, University of Virginia, Charlottesville, Virginia, United States of America
- * E-mail:
| |
Collapse
|
132
|
Climatic seasonality may affect ecological network structure: food webs and mutualistic networks. Biosystems 2014; 121:29-37. [PMID: 24907523 DOI: 10.1016/j.biosystems.2014.06.002] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2014] [Revised: 05/30/2014] [Accepted: 06/02/2014] [Indexed: 11/23/2022]
Abstract
Ecological networks exhibit non-random structural patterns, such as modularity and nestedness, which determine ecosystem stability with species diversity and connectance. Such structure-stability relationships are well known. However, another important perspective is less well understood: the relationship between the environment and structure. Inspired by theoretical studies that suggest that network structure can change due to environmental variability, we collected data on a number of empirical food webs and mutualistic networks and evaluated the effect of climatic seasonality on ecological network structure. As expected, we found that climatic seasonality affects ecological network structure. In particular, an increase in modularity due to climatic seasonality was observed in food webs; however, it is debatable whether this occurs in mutualistic networks. Interestingly, the type of climatic seasonality that affects network structure differs with ecosystem type. Rainfall and temperature seasonality influence freshwater food webs and mutualistic networks, respectively; food webs are smaller, and more modular, with increasing rainfall seasonality. Mutualistic networks exhibit a higher diversity (particularly of animals) with increasing temperature seasonality. These results confirm the theoretical prediction that the stability increases with greater perturbation. Although these results are still debatable because of several limitations in the data analysis, they may enhance our understanding of environment-structure relationships.
Collapse
|
133
|
Fort H. Quantitative predictions of pollinators’ abundances from qualitative data on their interactions with plants and evidences of emergent neutrality. OIKOS 2014. [DOI: 10.1111/oik.01539] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Affiliation(s)
- Hugo Fort
- Complex Systems Group, Inst. of Physics, Facultad de Ciencias, Univ. de la República; UY-11400 Montevideo Uruguay
| |
Collapse
|
134
|
|
135
|
Minoarivelo HO, Hui C, Terblanche JS, Pond SLK, Scheffler K. Detecting phylogenetic signal in mutualistic interaction networks using a Markov process model. OIKOS 2014; 123:1250-1260. [PMID: 25294947 DOI: 10.1111/oik.00857] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Ecological interaction networks, such as those describing the mutualistic interactions between plants and their pollinators or between plants and their frugivores, exhibit non-random structural properties that cannot be explained by simple models of network formation. One factor affecting the formation and eventual structure of such a network is its evolutionary history. We argue that this, in many cases, is closely linked to the evolutionary histories of the species involved in the interactions. Indeed, empirical studies of interaction networks along with the phylogenies of the interacting species have demonstrated significant associations between phylogeny and network structure. To date, however, no generative model explaining the way in which the evolution of individual species affects the evolution of interaction networks has been proposed. We present a model describing the evolution of pairwise interactions as a branching Markov process, drawing on phylogenetic models of molecular evolution. Using knowledge of the phylogenies of the interacting species, our model yielded a significantly better fit to 21% of a set of plant - pollinator and plant - frugivore mutualistic networks. This highlights the importance, in a substantial minority of cases, of inheritance of interaction patterns without excluding the potential role of ecological novelties in forming the current network architecture. We suggest that our model can be used as a null model for controlling evolutionary signals when evaluating the role of other factors in shaping the emergence of ecological networks.
Collapse
Affiliation(s)
- H O Minoarivelo
- H. O. Minoarivelo and K. Scheffler ( ), Computer Science Division, Dept of Mathematical Sciences, Stellenbosch Univ., Matieland 7602, South Africa. - HOM and C. Hui, Centre for Invasion Biology, Dept of Mathematical Sciences, Stellenbosch Univ., Matieland 7602, South Africa. - KS and S. L. Kosakovsky Pond, Dept of Medicine, Univ. of California, San Diego, USA. - J. S. Terblanche, Centre for Invasion Biology, Dept of Conservation Ecology and Entomology, Stellenbosch Univ., Matieland 7602, South Africa
| | - C Hui
- H. O. Minoarivelo and K. Scheffler ( ), Computer Science Division, Dept of Mathematical Sciences, Stellenbosch Univ., Matieland 7602, South Africa. - HOM and C. Hui, Centre for Invasion Biology, Dept of Mathematical Sciences, Stellenbosch Univ., Matieland 7602, South Africa. - KS and S. L. Kosakovsky Pond, Dept of Medicine, Univ. of California, San Diego, USA. - J. S. Terblanche, Centre for Invasion Biology, Dept of Conservation Ecology and Entomology, Stellenbosch Univ., Matieland 7602, South Africa
| | - J S Terblanche
- H. O. Minoarivelo and K. Scheffler ( ), Computer Science Division, Dept of Mathematical Sciences, Stellenbosch Univ., Matieland 7602, South Africa. - HOM and C. Hui, Centre for Invasion Biology, Dept of Mathematical Sciences, Stellenbosch Univ., Matieland 7602, South Africa. - KS and S. L. Kosakovsky Pond, Dept of Medicine, Univ. of California, San Diego, USA. - J. S. Terblanche, Centre for Invasion Biology, Dept of Conservation Ecology and Entomology, Stellenbosch Univ., Matieland 7602, South Africa
| | - S L Kosakovsky Pond
- H. O. Minoarivelo and K. Scheffler ( ), Computer Science Division, Dept of Mathematical Sciences, Stellenbosch Univ., Matieland 7602, South Africa. - HOM and C. Hui, Centre for Invasion Biology, Dept of Mathematical Sciences, Stellenbosch Univ., Matieland 7602, South Africa. - KS and S. L. Kosakovsky Pond, Dept of Medicine, Univ. of California, San Diego, USA. - J. S. Terblanche, Centre for Invasion Biology, Dept of Conservation Ecology and Entomology, Stellenbosch Univ., Matieland 7602, South Africa
| | - K Scheffler
- H. O. Minoarivelo and K. Scheffler ( ), Computer Science Division, Dept of Mathematical Sciences, Stellenbosch Univ., Matieland 7602, South Africa. - HOM and C. Hui, Centre for Invasion Biology, Dept of Mathematical Sciences, Stellenbosch Univ., Matieland 7602, South Africa. - KS and S. L. Kosakovsky Pond, Dept of Medicine, Univ. of California, San Diego, USA. - J. S. Terblanche, Centre for Invasion Biology, Dept of Conservation Ecology and Entomology, Stellenbosch Univ., Matieland 7602, South Africa
| |
Collapse
|
136
|
|
137
|
Song Z, Feldman MW. Adaptive foraging behaviour of individual pollinators and the coexistence of co-flowering plants. Proc Biol Sci 2013; 281:20132437. [PMID: 24352943 DOI: 10.1098/rspb.2013.2437] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Although pollinators can play a central role in determining the structure and stability of plant communities, little is known about how their adaptive foraging behaviours at the individual level, e.g. flower constancy, structure these interactions. Here, we construct a mathematical model that integrates individual adaptive foraging behaviour and population dynamics of a community consisting of two plant species and a pollinator species. We find that adaptive foraging at the individual level, as a complementary mechanism to adaptive foraging at the species level, can further enhance the coexistence of plant species through niche partitioning between conspecific pollinators. The stabilizing effect is stronger than that of unbiased generalists when there is also strong competition between plant species over other resources, but less so than that of multiple specialist species. This suggests that adaptive foraging in mutualistic interactions can have a very different impact on the plant community structure from that in predator-prey interactions. In addition, the adaptive behaviour of individual pollinators may cause a sharp regime shift for invading plant species. These results indicate the importance of integrating individual adaptive behaviour and population dynamics for the conservation of native plant communities.
Collapse
Affiliation(s)
- Zhiyuan Song
- Department of Biology, Stanford University, , Stanford, CA 94305, USA
| | | |
Collapse
|
138
|
Suweis S, Grilli J, Maritan A. Disentangling the effect of hybrid interactions and of the constant effort hypothesis on ecological community stability. OIKOS 2013. [DOI: 10.1111/j.1600-0706.2013.00822.x] [Citation(s) in RCA: 46] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
|
139
|
Statistical Mechanics Ideas and Techniques Applied to Selected Problems in Ecology. ENTROPY 2013. [DOI: 10.3390/e15125237] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
|
140
|
|