Statistical inference for food webs with emphasis on ecological networks via Bayesian melding

2009 ◽  
Vol 21 (7-8) ◽  
pp. 728-740 ◽  
Author(s):  
Grace S. Chiu ◽  
Joshua M. Gould
Keyword(s):  
Food Webs ◽  
Statistical Inference ◽  
Ecological Networks

scholarly journals Reconstruction of plant–pollinator networks from observational data

2019 ◽  
Author(s):  
Jean-Gabriel Young ◽  
Fernanda S. Valdovinos ◽  
M. E. J. Newman
Keyword(s):  
Food Webs ◽  
Observational Data ◽  
Network Structure ◽  
Rare Species ◽  
Statistical Technique ◽  
Ecological Networks ◽  
Statistical Analyses ◽  
Published Data ◽  
Statistical Errors ◽  
Plant Pollinator

Empirical measurements of ecological networks such as food webs and mutualistic networks are often rich in structure but also noisy and error-prone, particularly for rare species for which observations are sparse. Focusing on the case of plant–pollinator networks, we here describe a Bayesian statistical technique that allows us to make accurate estimates of network structure and ecological metrics from such noisy observational data. Our method yields not only estimates of these quantities, but also estimates of their statistical errors, paving the way for principled statistical analyses of ecological variables and outcomes. We demonstrate the use of the method with an application to previously published data on plant–pollinator networks in the Seychelles archipelago, calculating estimates of network structure, network nestedness, and other characteristics.

The Structure of Ecological Networks Across Levels of Organization

2020 ◽  
Vol 51 (1) ◽  
pp. 433-460 ◽  
Author(s):  
Paulo R. Guimarães
Keyword(s):  
Food Webs ◽  
Ecological Systems ◽  
Ecological Networks ◽  
Ecological Communities ◽  
Ecological Interactions ◽  
Biological Organization ◽  
Architectural Patterns ◽  
Fundamental Challenge ◽  
Spatiotemporal Scales ◽  
Multiple Levels

Interactions connect the units of ecological systems, forming networks. Individual-based networks characterize variation in niches among individuals within populations. These individual-based networks merge with each other, forming species-based networks and food webs that describe the architecture of ecological communities. Networks at broader spatiotemporal scales portray the structure of ecological interactions across landscapes and over macroevolutionary time. Here, I review the patterns observed in ecological networks across multiple levels of biological organization. A fundamental challenge is to understand the amount of interdependence as we move from individual-based networks to species-based networks and beyond. Despite the uneven distribution of studies, regularities in network structure emerge across scales due to the fundamental architectural patterns shared by complex networks and the interplay between traits and numerical effects. I illustrate the integration of these organizational scales by exploring the consequences of the emergence of highly connected species for network structures across scales.

scholarly journals Food Webs Over Time: Evaluating the Variability of Degree Distribution on Ecological Networks

2017 ◽  
Author(s):  
Daniela N Lopez ◽  
Patricio A Camus ◽  
Nelson Valdivia ◽  
Sergio A Estay
Keyword(s):  
Food Webs ◽  
Functional Form ◽  
Exponential Model ◽  
Ecological Networks ◽  
Specific Interactions ◽  
Distribution Models ◽  
Networks Analysis ◽  
Topological Characteristics ◽  
Time Specific ◽  
Over Time

AbstractAlthough networks analysis has moved from static to dynamic, ecological networks are still analyzed as time-aggregated units where time-specific interactions are aggregated into one single network. As a result, several questions arise such as what is the functional form of and how variable is the topology of time-specific versus time-aggregated ecological networks? Furthermore, it is yet unknown to what extent the structure of time-aggregated networks is representative of the dynamics of the community. Here, we compared the topology of time-specific and time-aggregated networks by analyzing a set of intertidal networks containing more than 1,000 interactions, and assessed the spatiotemporal dynamics of their degree distributions. By fitting different distribution models, we found that the out-degree distributions of seasonal and time-aggregated networks were best described by an exponential model while the in-degree distributions were best described by a discrete generalized beta model. The degree distributions of the seasonal networks were highly temporally variable and are significantly different from those of time-aggregated networks. We observed that seasonal degree distributions converged toward time-aggregated network distributions after 1.5 years of sampling. Our results highlight the importance of understanding the dynamics of ecological networks, which can show topological characteristics significantly different from those of time-aggregated networks.

scholarly journals Phenotypic evolution is more constrained in simpler food webs

2019 ◽  
Author(s):  
Matthew A. Barbour ◽  
Christopher J. Greyson-Gaito ◽  
Arezoo Sootodeh ◽  
Brendan Locke ◽  
Jordi Bascompte
Keyword(s):  
Food Web ◽  
Food Webs ◽  
Ecological Networks ◽  
Community Context ◽  
Relative Fitness ◽  
Adaptive Landscape ◽  
Phenotypic Traits ◽  
Phenotypic Evolution ◽  
Adaptive Landscapes ◽  
Food Web Complexity

AbstractGlobal change is simplifying the structure of ecological networks; however, we are currently in a poor position to predict how these simplified communities will affect the evolutionary potential of remaining populations. Theory on adaptive landscapes provides a framework for predicting how selection constrains phenotypic evolution, but often treats the community context of evolving populations as a “black box”. Here, we integrate ecological networks and adaptive landscapes to examine how changes in food-web complexity shape evolutionary constraints. We conducted a field experiment that manipulated the diversity of insect parasitoids (food-web complexity) that were able to impose selection on an insect herbivore. We then measured herbivore survival as a function of three key phenotypic traits. We found that more traits were under selection in simpler vs. more complex food webs. The adaptive landscape was more neutral in complex food webs because different parasitoid species impose different selection pressures, minimizing relative fitness differences among phenotypes. Our results suggest that phenotypic evolution becomes more constrained in simplified food webs. This indicates that the simplification of ecological communities may constrain the adaptive potential of remaining populations to future environmental change. “What escapes the eye, however, is a much more insidious kind of extinction: the extinction of ecological interactions.” Janzen (1974)

scholarly journals Degree heterogeneity and stability of ecological networks

2017 ◽  
Vol 14 (131) ◽  
pp. 20170189 ◽  
Author(s):  
Gang Yan ◽  
Neo D. Martinez ◽  
Yang-Yu Liu
Keyword(s):  
Food Webs ◽  
Network Architecture ◽  
Interspecific Interactions ◽  
Ecological Networks ◽  
Ecological Stability ◽  
Small Perturbations ◽  
Return To Equilibrium ◽  
Predator Prey ◽  
Fundamental Properties ◽  
The Stability

A classic measure of ecological stability describes the tendency of a community to return to equilibrium after small perturbations. While many advances show how the network architecture of these communities severely constrains such tendencies, one of the most fundamental properties of network structure, i.e. degree heterogeneity—the variability of the number of links associated with each species, deserves further study. Here we show that the effects of degree heterogeneity on stability vary with different types of interspecific interactions. Degree heterogeneity consistently destabilizes ecological networks with both competitive and mutualistic interactions, while its effects on networks of predator–prey interactions such as food webs depend on prey contiguity, i.e. the extent to which the species consume an unbroken sequence of prey in community niche space. Increasing degree heterogeneity tends to stabilize food webs except those with the highest prey contiguity. These findings help explain why food webs are highly but not completely interval and, more broadly, deepen our understanding of the stability of complex ecological networks.

scholarly journals Parallel ecological networks in ecosystems

2009 ◽  
Vol 364 (1524) ◽  
pp. 1755-1779 ◽  
Author(s):  
Han Olff ◽  
David Alonso ◽  
Matty P. Berg ◽  
B. Klemens Eriksson ◽  
Michel Loreau ◽  
...  
Keyword(s):  
Food Webs ◽  
Trophic Position ◽  
Abiotic Factors ◽  
Ecological Networks ◽  
Test Cases ◽  
Predator Prey ◽  
Ecological Interaction ◽  
Plant Parts ◽  
Food Web Interactions ◽  
New Ideas

In ecosystems, species interact with other species directly and through abiotic factors in multiple ways, often forming complex networks of various types of ecological interaction. Out of this suite of interactions, predator–prey interactions have received most attention. The resulting food webs, however, will always operate simultaneously with networks based on other types of ecological interaction, such as through the activities of ecosystem engineers or mutualistic interactions. Little is known about how to classify, organize and quantify these other ecological networks and their mutual interplay. The aim of this paper is to provide new and testable ideas on how to understand and model ecosystems in which many different types of ecological interaction operate simultaneously. We approach this problem by first identifying six main types of interaction that operate within ecosystems, of which food web interactions are one. Then, we propose that food webs are structured among two main axes of organization: a vertical (classic) axis representing trophic position and a new horizontal ‘ecological stoichiometry’ axis representing decreasing palatability of plant parts and detritus for herbivores and detrivores and slower turnover times. The usefulness of these new ideas is then explored with three very different ecosystems as test cases: temperate intertidal mudflats; temperate short grass prairie; and tropical savannah.

Species interactions in ecological networks

2019 ◽  
pp. 179-205
Author(s):  
Gary G. Mittelbach ◽  
Brian J. McGill
Keyword(s):  
Food Webs ◽  
Species Interactions ◽  
Ecological Networks ◽  
Weak Links ◽  
Future Research ◽  
Positive Interactions ◽  
Trophic Links ◽  
Mutualistic Networks ◽  
The Many ◽  
Potential Interactions

This chapter explores ecological networks and their properties. Ecological networks summarize the many potential interactions between species within a community by representing species as nodes in the network and using links between nodes to represent the interactions between species. The earliest and best-studied ecological networks are food webs that describe who eats whom within a community (trophic links). Most food webs contain a few strong and many weak links between species; the preponderance of weak links promotes food web stability. Body size is a key trait in determining the pattern and strength of trophic interactions in food webs. Mutualistic networks describe the positive interactions between species in a community, where patterns of species associations may be characterized as either “nested” or “modular”. Nestedness may increase stability in mutualistic networks. A major challenge to future research is to incorporate multiple types of species interactions into the same ecological network.

FROM FOOD WEBS TO ECOLOGICAL NETWORKS

2005 ◽  
pp. 27-36 ◽  
Author(s):  
Ulrich Brose ◽  
Eric L. Berlow ◽  
Neo D. Martinez
Keyword(s):  
Food Webs ◽  
Ecological Networks
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