Ecological Network Analysis Metrics
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Identifying a Common Backbone of Interactions Underlying Food Webs from Different Ecosystems
ARTICLE DOI: 10.1038/s41467-018-05056-0 OPEN Identifying a common backbone of interactions underlying food webs from different ecosystems Bernat Bramon Mora1, Dominique Gravel2,3, Luis J. Gilarranz4, Timothée Poisot 2,5 & Daniel B. Stouffer 1 Although the structure of empirical food webs can differ between ecosystems, there is growing evidence of multiple ways in which they also exhibit common topological properties. To reconcile these contrasting observations, we postulate the existence of a backbone of — 1234567890():,; interactions underlying all ecological networks a common substructure within every net- work comprised of species playing similar ecological roles—and a periphery of species whose idiosyncrasies help explain the differences between networks. To test this conjecture, we introduce a new approach to investigate the structural similarity of 411 food webs from multiple environments and biomes. We first find significant differences in the way species in different ecosystems interact with each other. Despite these differences, we then show that there is compelling evidence of a common backbone of interactions underpinning all food webs. We expect that identifying a backbone of interactions will shed light on the rules driving assembly of different ecological communities. 1 Centre for Integrative Ecology, School of Biological Sciences, University of Canterbury, Christchurch 8041, New Zealand. 2 Québec Centre for Biodiversity Sciences, McGill University, Montréal H3A 0G4, Canada. 3 Canada Research Chair on Integrative Ecology, Départment de Biologie, Université de Sherbrooke, Sherbrooke J1K 2R1, Canada. 4 Department of Evolutionary Biology and Environmental Studies, University of Zurich, 8006 Zurich, Switzerland. 5 Département de Sciences Biologiques, Université de Montréal, Montréal H3T 1J4, Canada. -
Ecosystem Services Generated by Fish Populations
AR-211 Ecological Economics 29 (1999) 253 –268 ANALYSIS Ecosystem services generated by fish populations Cecilia M. Holmlund *, Monica Hammer Natural Resources Management, Department of Systems Ecology, Stockholm University, S-106 91, Stockholm, Sweden Abstract In this paper, we review the role of fish populations in generating ecosystem services based on documented ecological functions and human demands of fish. The ongoing overexploitation of global fish resources concerns our societies, not only in terms of decreasing fish populations important for consumption and recreational activities. Rather, a number of ecosystem services generated by fish populations are also at risk, with consequences for biodiversity, ecosystem functioning, and ultimately human welfare. Examples are provided from marine and freshwater ecosystems, in various parts of the world, and include all life-stages of fish. Ecosystem services are here defined as fundamental services for maintaining ecosystem functioning and resilience, or demand-derived services based on human values. To secure the generation of ecosystem services from fish populations, management approaches need to address the fact that fish are embedded in ecosystems and that substitutions for declining populations and habitat losses, such as fish stocking and nature reserves, rarely replace losses of all services. © 1999 Elsevier Science B.V. All rights reserved. Keywords: Ecosystem services; Fish populations; Fisheries management; Biodiversity 1. Introduction 15 000 are marine and nearly 10 000 are freshwa ter (Nelson, 1994). Global capture fisheries har Fish constitute one of the major protein sources vested 101 million tonnes of fish including 27 for humans around the world. There are to date million tonnes of bycatch in 1995, and 11 million some 25 000 different known fish species of which tonnes were produced in aquaculture the same year (FAO, 1997). -
7. NETWORK FLOW II ‣ Bipartite Matching ‣ Disjoint Paths
Soviet rail network (1950s) "Free world" goal. Cut supplies (if cold war turns into real war). 7. NETWORK FLOW II ‣ bipartite matching ‣ disjoint paths ‣ extensions to max flow ‣ survey design ‣ airline scheduling ‣ image segmentation ‣ project selection Lecture slides by Kevin Wayne ‣ baseball elimination Copyright © 2005 Pearson-Addison Wesley http://www.cs.princeton.edu/~wayne/kleinberg-tardos Reference: On the history of the transportation and maximum flow problems. Alexander Schrijver in Math Programming, 91: 3, 2002. Last updated on Mar 31, 2013 3:25 PM Figure 2 2 From Harris and Ross [1955]: Schematic diagram of the railway network of the Western So- viet Union and Eastern European countries, with a maximum flow of value 163,000 tons from Russia to Eastern Europe, and a cut of capacity 163,000 tons indicated as ‘The bottleneck’. Max-flow and min-cut applications Max-flow and min-cut are widely applicable problem-solving model. ・Data mining. 7. NETWORK FLOW II ・Open-pit mining. ・Bipartite matching. ‣ bipartite matching ・Network reliability. ‣ disjoint paths ・Baseball elimination. ‣ extensions to max flow ・Image segmentation. ・Network connectivity. ‣ survey design liver and hepatic vascularization segmentation ・Distributed computing. ‣ airline scheduling ・Security of statistical data. ‣ image segmentation ・Egalitarian stable matching. ・Network intrusion detection. ‣ project selection ・Multi-camera scene reconstruction. ‣ baseball elimination ・Sensor placement for homeland security. ・Many, many, more. 3 Matching Bipartite matching Def. Given an undirected graph G = (V, E) a subset of edges M ⊆ E is Def. A graph G is bipartite if the nodes can be partitioned into two subsets a matching if each node appears in at most one edge in M. -
Models for Networks with Consumable Resources: Applications to Smart Cities Hayato Montezuma Ushijima-Mwesigwa Clemson University, [email protected]
Clemson University TigerPrints All Dissertations Dissertations 12-2018 Models for Networks with Consumable Resources: Applications to Smart Cities Hayato Montezuma Ushijima-Mwesigwa Clemson University, [email protected] Follow this and additional works at: https://tigerprints.clemson.edu/all_dissertations Recommended Citation Ushijima-Mwesigwa, Hayato Montezuma, "Models for Networks with Consumable Resources: Applications to Smart Cities" (2018). All Dissertations. 2284. https://tigerprints.clemson.edu/all_dissertations/2284 This Dissertation is brought to you for free and open access by the Dissertations at TigerPrints. It has been accepted for inclusion in All Dissertations by an authorized administrator of TigerPrints. For more information, please contact [email protected]. Models for Networks with Consumable Resources: Applications to Smart Cities A Dissertation Presented to the Graduate School of Clemson University In Partial Fulfillment of the Requirements for the Degree Doctor of Philosophy Computer Science by Hayato Ushijima-Mwesigwa December 2018 Accepted by: Dr. Ilya Safro, Committee Chair Dr. Mashrur Chowdhury Dr. Brian Dean Dr. Feng Luo Abstract In this dissertation, we introduce different models for understanding and controlling the spreading dynamics of a network with a consumable resource. In particular, we consider a spreading process where a resource necessary for transit is partially consumed along the way while being refilled at special nodes on the network. Examples include fuel consumption of vehicles together with refueling stations, information loss during dissemination with error correcting nodes, consumption of ammunition of military troops while moving, and migration of wild animals in a network with a limited number of water-holes. We undertake this study from two different perspectives. First, we consider a network science perspective where we are interested in identifying the influential nodes, and estimating a nodes’ relative spreading influence in the network. -
Limits on Ecosystem Trophic Complexity: Insights from Ecological Network Analysis
Ecology Letters, (2014) 17: 127–136 doi: 10.1111/ele.12216 IDEA AND PERSPECTIVE Limits on ecosystem trophic complexity: insights from ecological network analysis Abstract Robert E. Ulanowicz,1,2* Robert D. Articulating what limits the length of trophic food chains has remained one of the most enduring Holt1 and Michael Barfield1 challenges in ecology. Mere counts of ecosystem species and transfers have not much illumined the issue, in part because magnitudes of trophic transfers vary by orders of magnitude in power- law fashion. We address this issue by creating a suite of measures that extend the basic indexes usually obtained by counting taxa and transfers so as to apply to networks wherein magnitudes vary by orders of magnitude. Application of the extended measures to data on ecosystem trophic networks reveals that the actual complexity of ecosystem webs is far less than usually imagined, because most ecosystem networks consist of a multitude of weak connections dominated by a rel- atively few strong flows. Although quantitative ecosystem networks may consist of hundreds of nodes and thousands of transfers, they nevertheless behave similarly to simpler representations of systems with fewer than 14 nodes or 40 flows. Both theory and empirical data point to an upper bound on the number of effective trophic levels at about 3–4 links. We suggest that several whole-system processes may be at play in generating these ecosystem limits and regularities. Keywords Connectivity, ecosystem roles, food chain length, network complexity, system flexibility, system roles, trophic breadth, trophic depth, window of vitality. Ecology Letters (2014) 17: 127–136 2009); some herbivores (megaherbivores) evolve to sizes AN ENDURING QUESTION IN ECOLOGY: WHAT whereby they largely escape predation, thus truncating the LIMITS FOOD CHAIN LENGTH? food chain. -
Structural Graph Theory Meets Algorithms: Covering And
Structural Graph Theory Meets Algorithms: Covering and Connectivity Problems in Graphs Saeed Akhoondian Amiri Fakult¨atIV { Elektrotechnik und Informatik der Technischen Universit¨atBerlin zur Erlangung des akademischen Grades Doktor der Naturwissenschaften Dr. rer. nat. genehmigte Dissertation Promotionsausschuss: Vorsitzender: Prof. Dr. Rolf Niedermeier Gutachter: Prof. Dr. Stephan Kreutzer Gutachter: Prof. Dr. Marcin Pilipczuk Gutachter: Prof. Dr. Dimitrios Thilikos Tag der wissenschaftlichen Aussprache: 13. October 2017 Berlin 2017 2 This thesis is dedicated to my family, especially to my beautiful wife Atefe and my lovely son Shervin. 3 Contents Abstract iii Acknowledgementsv I. Introduction and Preliminaries1 1. Introduction2 1.0.1. General Techniques and Models......................3 1.1. Covering Problems.................................6 1.1.1. Covering Problems in Distributed Models: Case of Dominating Sets.6 1.1.2. Covering Problems in Directed Graphs: Finding Similar Patterns, the Case of Erd}os-P´osaproperty.......................9 1.2. Routing Problems in Directed Graphs...................... 11 1.2.1. Routing Problems............................. 11 1.2.2. Rerouting Problems............................ 12 1.3. Structure of the Thesis and Declaration of Authorship............. 14 2. Preliminaries and Notations 16 2.1. Basic Notations and Defnitions.......................... 16 2.1.1. Sets..................................... 16 2.1.2. Graphs................................... 16 2.2. Complexity Classes................................ -
Florida's Ecological Network
Green Infrastructure — Linking Lands for Nature and People Case Study Series Florida’s Ecological Network Photo by Jane M. Rohling / USFWS Vision Overview "In the 21st century, Florida has a protected system of The Florida Greenways Commission defined a greenways that is planned and managed to conserve “greenways system” as a “system of native landscapes native landscapes, ecosystems and their species; and and ecosystems that supports native plant and animal to connect people to the land . Florida's diverse species, sustains clean air, water, fisheries, and other wildlife species are able to move . within their natural resources, and maintains the scenic natural ranges with less danger of being killed on roadways or beauty that draws people to visit and settle in Florida.” becoming lost in towns or Greenways follow natural land or water features such cities. Native landscapes as ridges or rivers or human landscape features such and ecosystems are as abandoned railroad corridors or canals. A healthy, protected, managed, and well functioning system of greenways can support restored through strong wildlife communities and provide innumerable benefits public and private to Florida’s people, as well. The Commission saw a partnerships. Sensitive healthy and diverse green infrastructure as the riverine and coastal underlying basis of Florida’s sustainable future. They waterways are effectively identified two components to the statewide greenways protected by buffers of green, open space and working system: the Ecological Network and the Recreational/ landscapes. Florida's rich system of greenways Cultural Network (Figure 1). We focus here on the helps sustain Florida's future by conserving its green Ecological Network. -
Predicting Ecosystem Functions from Biodiversity and Mutualistic Networks: an Extension of Trait-Based Concepts to Plant– Animal Interactions
Ecography 38: 380–392, 2015 doi: 10.1111/ecog.00983 © 2014 Th e Authors. Ecography © 2014 Nordic Society Oikos Subject Editor: Jens-Christian Svenning. Editor-in-Chief: Jens-Christian Svenning. Accepted 24 October 2014 Predicting ecosystem functions from biodiversity and mutualistic networks: an extension of trait-based concepts to plant – animal interactions Matthias Schleuning , Jochen Fr ü nd and Daniel Garc í a Intecol special issue M. Schleuning ([email protected]), Biodiversity and Climate Research Centre (BiK-F) and Senckenberg Gesellschaft f ü r Naturforschung, Senckenberganlage 25, DE-60325 Frankfurt (Main), Germany. – J. Fr ü nd, Dept of Integrative Biology, Univ. of Guelph, ON N1G2W1, Canada. – D. Garc í a, Univ. of Oviedo, Depto Biolog í a de Organismos y Sistemas and Unidad Mixta de Investigaci ó n en Biodiversidad (CSIC-UO-PA), Valent í n Andr é s Á lvarez s/n, ES-33071 Oviedo (Asturias), Spain. Research linking biodiversity and ecosystem functioning (BEF) has been mostly centred on the infl uence of species rich- ness on ecosystem functions in small-scale experiments with single trophic levels. In natural ecosystems, many ecosystem functions are mediated by interactions between plants and animals, such as pollination and seed dispersal by animals, for which BEF relationships are little understood. Largely disconnected from BEF research, network ecology has examined the structural diversity of complex ecological networks of interacting species. Here, we provide an overview of the most impor- tant concepts in BEF and ecological network research and exemplify their applicability to natural ecosystems with examples from pollination and seed-dispersal studies. In a synthesis, we connect the structural approaches of network analysis with the trait-based approaches of BEF research and propose a conceptual trait-based model for understanding BEF relation- ships of plant – animal interactions in natural ecosystems. -
Overview of Network Environ Analysis: a Systems Analysis Technique for Understanding Complex Ecological Systems
Ecodinamica Overview of Network Environ Analysis: A systems analysis technique for understanding complex ecological systems Brian D. Fath 1,2,3 1Biology Department Towson University, Towson, Maryland, USA 2Fulbright Distinguished Chair in Energy and Environment, Parthenope University of Naples, Italy 3Advanced Systems Analysis Program, International Institute for Applied Systems Analysis, Austria Synopsis Network Environ Analysis, based on network theory, Analysis requires data including the intercompart - reveals the quantitative and qualitative relations be - mental flows, compartmental storages, and boundary tween ecological objects interacting with each other input and output flows. Software is available to per - in a system. The primary result from the method pro - form this analysis. This article reviews the theoretical vides input and output “environs”, which are inter - underpinning of the analysis and briefly introduces nal partitions of the objects within system flows. In some the main properties such as indirect effects ra - addition, application of Network Environ Analysis on tio, network homogenization, and network mutual - empirical datasets and ecosystem models has re - ism. References for further reading are provided. vealed several important and unexpected results that have been identified and summarized in the litera - Keywords: Systems ecology, connectivity, energy flows, ture as network environ properties. Network Environ network analysis, indirect effects, mutualism Introduction which is mostly concerned with interrelations of ma - terial, energy and information among system com - Environ Analysis is in a more general class of meth - ponents (Table 1). ods called Ecological Network Analysis (ENA) ENA starts with the assumption that a system can be which uses network theory to study the interactions represented as a network of nodes (compartments, between organisms or populations within their envi - objects, etc.) and the connections between them ronment. -
Ecological Network Metrics: Opportunities for Synthesis
University of Vermont ScholarWorks @ UVM College of Arts and Sciences Faculty Publications College of Arts and Sciences 8-1-2017 Ecological network metrics: Opportunities for synthesis Matthew K. Lau Harvard Forest Stuart R. Borrett University of North Carolina Wilmington Benjamin Baiser University of Florida Nicholas J. Gotelli University of Vermont Aaron M. Ellison Harvard Forest Follow this and additional works at: https://scholarworks.uvm.edu/casfac Part of the Climate Commons, Community Health Commons, Human Ecology Commons, Nature and Society Relations Commons, Place and Environment Commons, and the Sustainability Commons Recommended Citation Lau MK, Borrett SR, Baiser B, Gotelli NJ, Ellison AM. Ecological network metrics: opportunities for synthesis. Ecosphere. 2017 Aug;8(8):e01900. This Article is brought to you for free and open access by the College of Arts and Sciences at ScholarWorks @ UVM. It has been accepted for inclusion in College of Arts and Sciences Faculty Publications by an authorized administrator of ScholarWorks @ UVM. For more information, please contact [email protected]. INNOVATIVE VIEWPOINTS Ecological network metrics: opportunities for synthesis 1, 2,3 4 5 MATTHEW K. LAU, STUART R. BORRETT, BENJAMIN BAISER, NICHOLAS J. GOTELLI, 1 AND AARON M. ELLISON 1Harvard Forest, Harvard University, Petersham, Massachusetts 02138 USA 2Department of Biology and Marine Biology, University of North Carolina, Wilmington, North Carolina 28403 USA 3Duke Network Analysis Center, Social Science Research Institute, Duke University, Durham, North Carolina 27708 USA 4Department of Wildlife Ecology and Conservation, University of Florida, Gainesville, Florida 32611 USA 5Department of Biology, University of Vermont, Burlington, Vermont 05405 USA Citation: Lau, M. K., S. -
Network Flow - Theory and Applications with Practical Impact
3 Network flow - Theory and applications with practical impact Masao Iri Department of Information and System Engineering Faculty of Science and Engineering, Chuo University 1-13-27 Kasuga, Bunkyo-ku, Tokyo 112, Japan. Tel: +81-3-3817-1690. Fax: +81-3-3817-1681. e-mail: [email protected] Keywords Network flow, history, applications, duality, future 1 INTRODUCTION The research in this subject has now a long history and a large variety of related fields in science, engineering and operations research, and is still developing fast, especially in its algorithmic aspects, attracting many excellent senior as well as young researchers. And the space allotted to this paper is limited. So, in this paper I will not lay so much stress on particular frontiers of research in the subject as on the wider and historical viewpoint. Network-flow theory is one of the best studied and developed fields of optimization, and has important relations to quite different fields of science and technology such as com binatorial mathematics, algebraic topology, electric circuit theory, nonlinear continuum theory including plasticity theory, geographic information systems, VLSI design, etc., etc., besides standard applications to transportation, scheduling, etc. in operations research. An important point of view from which we should look at network flow theory is the "duality" viewpoint, to which due attention was paid at the earlier stages of development of the theory but which tends to be gradually ignored as time goes. Since the papers and books published on network flow are too many to cite here, I do not intend to compile even an incomplete list of references but only to cite a few which I directly mention and which I think tend to become obscured during the long history in spite of their ever lasting importance. -
Inequity in Searching for Knowledge in Organizations
The World is Not Small for Everyone: Inequity in Searching for Knowledge in Organizations _______________ Jasjit SINGH Morten HANSEN Joel PODOLNY 2010/11/ST/EFE (Revised version of 2009/49/ST/EFE) The World is Not Small for Everyone: Inequity in Searching for Knowledge in Organizations By Jasjit Singh * Morten T. Hansen** Joel M. Podolny*** ** February 2010 Revised version of INSEAD Working Paper 2009/49/ST/EFE * Assistant Professor of Strategy at INSEAD, 1 Ayer Rajah Avenue, Singapore 138676 Ph: +65 6799 5341 E-Mail: [email protected] ** Professor of Entrepreneurship at INSEAD, Boulevard de Constance, Fontainebleau 77305 France Ph: + 33 (0) 1 60 72 40 20 E-Mail: [email protected] *** Professor at Apple University, 1 Infinite Loop, MS 301-4AU, Cupertino, CA 95014, USA Email: [email protected] A working paper in the INSEAD Working Paper Series is intended as a means whereby a faculty researcher's thoughts and findings may be communicated to interested readers. The paper should be considered preliminary in nature and may require revision. Printed at INSEAD, Fontainebleau, France. Kindly do not reproduce or circulate without permission. ABSTRACT We explore why some employees may be at a disadvantage in searching for information in large complex organizations. The “small world” argument in social network theory emphasizes that people are on an average only a few connections away from the information they seek. However, we argue that such a network structure may benefit some people more than others. Specifically, some employees may have longer search paths in locating knowledge in an organization—their world may be large.