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Journal ArticleDOI

The dimensionality of ecological networks

TL;DR: It is shown that accounting for a few traits dramatically improves the understanding of the structure of ecological networks, and matching traits for resources and consumers, for example, fruit size and bill gape, are the most successful combinations.
Abstract: How many dimensions (trait-axes) are required to predict whether two species interact? This unanswered question originated with the idea of ecological niches, and yet bears relevance today for understanding what determines network structure. Here, we analyse a set of 200 ecological networks, including food webs, antagonistic and mutualistic networks, and find that the number of dimensions needed to completely explain all interactions is small ( < 10), with model selection favouring less than five. Using 18 high-quality webs including several species traits, we identify which traits contribute the most to explaining network structure. We show that accounting for a few traits dramatically improves our understanding of the structure of ecological networks. Matching traits for resources and consumers, for example, fruit size and bill gape, are the most successful combinations. These results link ecologically important species attributes to large-scale community structure.

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Citations
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Journal ArticleDOI
TL;DR: Taking spatial and temporal processes into account can further elucidate network variation and improve predictions of network responses to environmental change.
Abstract: Ecological networks have a long history in ecology, and a recent increase in network analyses across environmental gradients has revealed important changes in their structure, dynamics, and functioning. These changes can be broadly grouped according to three nonexclusive mechanisms: (a) changes in the species composition of the networks (driven by interaction patterns of invaders, nonrandom extinction of species according to their traits, or differences among species in population responses across gradients); (b) changes that alter interaction frequencies via changes in search efficiency (driven by altered habitat structure or metabolic rates) or changes in spatial and temporal overlap; and (c) changes to coevolutionary processes and patterns. Taking spatial and temporal processes into account can further elucidate network variation and improve predictions of network responses to environmental change. Emerging evidence links network structure to ecosystem functioning; however, scaling up to metanetworks o...

303 citations

Journal ArticleDOI
TL;DR: An overview of tools that can be used to describe and compare the functional and dynamic roles of species based on their position in the network and the organization of their interactions as well as associated new methods to test the significance of these results are described.
Abstract: Network approaches to ecological questions have been increasingly used, particularly in recent decades. The abstraction of ecological systems - such as communities - through networks of interactions between their components indeed provides a way to summarize this information with single objects. The methodological framework derived from graph theory also provides numerous approaches and measures to analyze these objects and can offer new perspectives on established ecological theories as well as tools to address new challenges. However, prior to using these methods to test ecological hypotheses, it is necessary that we understand, adapt, and use them in ways that both allow us to deliver their full potential and account for their limitations. Here, we attempt to increase the accessibility of network approaches by providing a review of the tools that have been developed so far, with - what we believe to be - their appropriate uses and potential limitations. This is not an exhaustive review of all methods and metrics, but rather, an overview of tools that are robust, informative, and ecologically sound. After providing a brief presentation of species interaction networks and how to build them in order to summarize ecological information of different types, we then classify methods and metrics by the types of ecological questions that they can be used to answer from global to local scales, including methods for hypothesis testing and future perspectives. Specifically, we show how the organization of species interactions in a community yields different network structures (e.g., more or less dense, modular or nested), how different measures can be used to describe and quantify these emerging structures, and how to compare communities based on these differences in structures. Within networks, we illustrate metrics that can be used to describe and compare the functional and dynamic roles of species based on their position in the network and the organization of their interactions as well as associated new methods to test the significance of these results. Lastly, we describe potential fruitful avenues for new methodological developments to address novel ecological questions.

298 citations


Cites background from "The dimensionality of ecological ne..."

  • ..., 2011) or arbitrary traits derived from the interactions themselves (Eklöf et al., 2013)....

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Journal ArticleDOI
TL;DR: This work proposes a conceptual framework to infer the backbone of biotic interaction networks within regional species pools, and concludes that preliminary descriptions of the web of life can be made by careful integration of data with theory.
Abstract: Inferring biotic interactions from functional, phylogenetic and geographical proxies remains one great challenge in ecology. We propose a conceptual framework to infer the backbone of biotic interaction networks within regional species pools. First, interacting groups are identified to order links and remove forbidden interactions between species. Second, additional links are removed by examination of the geographical context in which species co-occur. Third, hypotheses are proposed to establish interaction probabilities between species. We illustrate the framework using published food-webs in terrestrial and marine systems. We conclude that preliminary descriptions of the web of life can be made by careful integration of data with theory.

253 citations

Journal ArticleDOI
TL;DR: The use of ecological-network models to study the relationship between complexity and stability of natural ecosystems is the focus of this review, highlighting the theoretical debate and the lack of consensual agreement.
Abstract: Our planet is changing at paces never observed before. Species extinction is happening at faster rates than ever, greatly exceeding the five mass extinctions in the fossil record. Nevertheless, our lives are strongly based on services provided by ecosystems, thus the responses to global change of our natural heritage are of immediate concern. Understanding the relationship between complexity and stability of ecosystems is of key importance for the maintenance of the balance of human growth and the conservation of all the natural services that ecosystems provide. Mathematical network models can be used to simplify the vast complexity of the real world, to formally describe and investigate ecological phenomena, and to understand ecosystems propensity of returning to its functioning regime after a stress or a perturbation. The use of ecological-network models to study the relationship between complexity and stability of natural ecosystems is the focus of this review. The concept of ecological networks and their characteristics are first introduced, followed by central and occasionally contrasting definitions of complexity and stability. The literature on the relationship between complexity and stability in different types of models and in real ecosystems is then reviewed, highlighting the theoretical debate and the lack of consensual agreement. The summary of the importance of this line of research for the successful management and conservation of biodiversity and ecosystem services concludes the review.

251 citations

Journal ArticleDOI
TL;DR: The results establish the minimum dimensionality required for avian functional traits to predict subtle variation in trophic niches and provide a global framework for exploring the origin, function and conservation of bird diversity.
Abstract: Animals have diversified into a bewildering variety of morphological forms exploiting a complex configuration of trophic niches. Their morphological diversity is widely used as an index of ecosystem function, but the extent to which animal traits predict trophic niches and associated ecological processes is unclear. Here we use the measurements of nine key morphological traits for >99% bird species to show that avian trophic diversity is described by a trait space with four dimensions. The position of species within this space maps with 70-85% accuracy onto major niche axes, including trophic level, dietary resource type and finer-scale variation in foraging behaviour. Phylogenetic analyses reveal that these form-function associations reflect convergence towards predictable trait combinations, indicating that morphological variation is organized into a limited set of dimensions by evolutionary adaptation. Our results establish the minimum dimensionality required for avian functional traits to predict subtle variation in trophic niches and provide a global framework for exploring the origin, function and conservation of bird diversity.

247 citations

References
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Book
19 Jun 2013
TL;DR: The second edition of this book is unique in that it focuses on methods for making formal statistical inference from all the models in an a priori set (Multi-Model Inference).
Abstract: Introduction * Information and Likelihood Theory: A Basis for Model Selection and Inference * Basic Use of the Information-Theoretic Approach * Formal Inference From More Than One Model: Multi-Model Inference (MMI) * Monte Carlo Insights and Extended Examples * Statistical Theory and Numerical Results * Summary

36,993 citations

Journal ArticleDOI
01 Jul 2004-Ecology
TL;DR: This work has developed a quantitative theory for how metabolic rate varies with body size and temperature, and predicts how metabolic theory predicts how this rate controls ecological processes at all levels of organization from individuals to the biosphere.
Abstract: Metabolism provides a basis for using first principles of physics, chemistry, and biology to link the biology of individual organisms to the ecology of populations, communities, and ecosystems. Metabolic rate, the rate at which organisms take up, transform, and expend energy and materials, is the most fundamental biological rate. We have developed a quantitative theory for how metabolic rate varies with body size and temperature. Metabolic theory predicts how metabolic rate, by setting the rates of resource uptake from the environment and resource allocation to survival, growth, and reproduction, controls ecological processes at all levels of organization from individuals to the biosphere. Examples include: (1) life history attributes, including devel- opment rate, mortality rate, age at maturity, life span, and population growth rate; (2) population interactions, including carrying capacity, rates of competition and predation, and patterns of species diversity; and (3) ecosystem processes, including rates of biomass production and respiration and patterns of trophic dynamics. Data compiled from the ecological literature strongly support the theoretical predictions. Even- tually, metabolic theory may provide a conceptual foundation for much of ecology, just as genetic theory provides a foundation for much of evolutionary biology.

6,017 citations


"The dimensionality of ecological ne..." refers background in this paper

  • ...…coexistence at a single trophic level (Silvertown 2004); macro-ecological approaches explain several ecological patterns using species’ body mass and metabolic rate (Brown et al. 2004); and phenology drives recent models for the effect of climate change (Forrest et al. 2010; Diamond et al. 2011)....

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Book
01 Jan 1998
TL;DR: The first € price and the £ and $ price are net prices, subject to local VAT, and the €(D) includes 7% for Germany, the€(A) includes 10% for Austria.
Abstract: The first € price and the £ and $ price are net prices, subject to local VAT. Prices indicated with * include VAT for books; the €(D) includes 7% for Germany, the €(A) includes 10% for Austria. Prices indicated with ** include VAT for electronic products; 19% for Germany, 20% for Austria. All prices exclusive of carriage charges. Prices and other details are subject to change without notice. All errors and omissions excepted. K.P. Burnham, D.R. Anderson Model Selection and Multimodel Inference

4,406 citations

Book
15 Jun 2005
TL;DR: Picking up where his influential The Coevolutionary Process left off, John N. Thompson synthesizes the state of a rapidly developing science that integrates approaches from evolutionary ecology, population genetics, phylogeography, systematics, evolutionary biochemistry and physiology, and molecular biology.
Abstract: Coevolution - reciprocal evolutionary change in interacting species driven by natural selection - is one of the most important ecological and genetic processes organizing the earth's biodiversity: most plants and animals require coevolved interactions with other species to survive and reproduce. The Geographic Mosaic of Coevolution analyzes how the biology of species provides the raw material for long-term coevolution, evaluates how local coadaptation forms the basic module of coevolutionary change, and explores how the coevolutionary process reshapes locally coevolving interactions across the earth's constantly changing landscapes. Picking up where his influential The Coevolutionary Process left off, John N. Thompson synthesizes the state of a rapidly developing science that integrates approaches from evolutionary ecology, population genetics, phylogeography, systematics, evolutionary biochemistry and physiology, and molecular biology. Using models, data, and hypotheses to develop a complete conceptual framework, Thompson also draws on examples from a wide range of taxa and environments, illustrating the expanding breadth and depth of research in coevolutionary biology.

1,869 citations

Book
01 Jul 2003
TL;DR: Jonathan M. Chase and Mathew A. Leibold argue that the niche is an ideal tool with which to unify disparate research and theoretical approaches in contemporary ecology and develop a framework for understanding niches that is flexible enough to include a variety of small- and large-scale processes.
Abstract: Why do species live where they live? What determines the abundance and diversity of species in a given area? What role do species play in the functioning of entire ecosystems? All of these questions share a single core concept - the ecological niche. Although the niche concept has fallen into disfavour among ecologists in recent years, Jonathan M. Chase and Mathew A. Leibold argue that the niche is an ideal tool with which to unify disparate research and theoretical approaches in contemporary ecology. Chase and Leibold define the niche as including both what an organism needs from its environment and how that organism's activities shape its environment. Drawing on the theory of consumer-resource interactions, as well as its graphical analysis, they develop a framework for understanding niches that is flexible enough to include a variety of small- and large-scale processes, from resource competition, predation and stress to community structure, biodiversity and ecosystem function. Chase and Leibold's synthetic approach should interest ecologists from a wide range of subdisciplines.

1,336 citations


"The dimensionality of ecological ne..." refers background in this paper

  • ...This is the familiar idea of multidimensional ecological niche pioneered by Grinell, Elton and Hutchinson (Chase & Leibold 2003)....

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