Comparing species interaction networks along environmental gradients
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Author(s)
Pellissier, Loïc
Albouy, Camille
Bascompte, Jordi
Farwig, Nina
Graham, Catherine
Loreau, Michel
Maglianesi, Maria Alejandra
Melián, Carlos J.
Pitteloud, Camille
Roslin, Tomas
Date Issued
September 2017
Journal
Biological Reviews
Publisher
Wiley Blackwell
Citation
Pellissier, Loïc et al. “Comparing Species Interaction Networks Along Environmental Gradients.” Biological Reviews 93, 2 (September 2017): 785–800 © 2017 Cambridge Philosophical Society
Version
Author's final manuscript
Abstract
Knowledge of species composition and their interactions, in the form of interaction networks, is required to understand processes shaping their distribution over time and space. As such, comparing ecological networks along environmental gradients represents a promising new research avenue to understand the organization of life. Variation in the position and intensity of links within networks along environmental gradients may be driven by turnover in species composition, by variation in species abundances and by abiotic influences on species interactions. While investigating changes in species composition has a long tradition, so far only a limited number of studies have examined changes in species interactions between networks, often with differing approaches. Here, we review studies investigating variation in network structures along environmental gradients, highlighting how methodological decisions about standardization can influence their conclusions. Due to their complexity, variation among ecological networks is frequently studied using properties that summarize the distribution or topology of interactions such as number of links, connectance, or modularity. These properties can either be compared directly or using a procedure of standardization. While measures of network structure can be directly related to changes along environmental gradients, standardization is frequently used to facilitate interpretation of variation in network properties by controlling for some co‐variables, or via null models. Null models allow comparing the deviation of empirical networks from random expectations and are expected to provide a more mechanistic understanding of the factors shaping ecological networks when they are coupled with functional traits. As an illustration, we compare approaches to quantify the role of trait matching in driving the structure of plant–hummingbird mutualistic networks, i.e. a direct comparison, standardized by null models and hypothesis‐based metaweb. Overall, our analysis warns against a comparison of studies that rely on distinct forms of standardization, as they are likely to highlight different signals. Fostering a better understanding of the analytical tools available and the signal they detect will help produce deeper insights into how and why ecological networks vary along environmental gradients. Keywords: network; metaweb; motif; rarefaction analysis; null model; environmental gradient; network comparison; network properties
MIT Department
Massachusetts Institute of Technology. Department of Civil and Environmental Engineering
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Creative Commons Attribution-Noncommercial-Share Alike
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DOI of Published Version
https://doi.org/10.1111/BRV.12366
