DOI: 10.5061/dryad.39jv1
title: Data from: What can interaction webs tell us about species roles?

description: The group model is a useful tool to understand broad-scale patterns of
 interaction in a network, but it has previously been limited in use to
 food webs, which contain only predator-prey interactions. Natural
 populations interact with each other in a variety of ways and, although
 most published ecological networks only include information about a single
 interaction type (e.g., feeding, pollination), ecologists are beginning to
 consider networks which combine multiple interaction types. Here we extend
 the group model to signed directed networks such as ecological interaction
 webs. As a specific application of this method, we examine the effects of
 including or excluding specific interaction types on our understanding of
 species roles in ecological networks. We consider all three currently
 available interaction webs, two of which are extended plant-mutualist
 networks with herbivores and parasitoids added, and one of which is an
 extended intertidal food web with interactions of all possible sign
 structures (+/+, -/0, etc.). Species in the extended food web grouped
 similarly with all interactions, only trophic links, and only nontrophic
 links. However, removing mutualism or herbivory had a much larger effect
 in the extended plant-pollinator webs. Species removal even affected
 groups that were not directly connected to those that were removed, as we
 found by excluding a small number of parasitoids. These results suggest
 that including additional species in the network provides far more
 information than additional interactions for this aspect of network
 structure. Our methods provide a useful framework for simplifying networks
 to their essential structure, allowing us to identify generalities in
 network structure and better understand the roles species play in their
 communities.
description: Tatoosh Non-trophic
 InteractionsText file containing a
 matrix indicating absence (0) positive (1) or negative (-1) non-feeding
 effects of one species (across columns of the matrix) on another species
 (down rows of the matrix) from the middle intertidal (mussel-dominated)
 zone of Tatoosh Island, Washington, USA. Species names and order
 corresponding to matrix columns/rows are found in file
 TatooshSpeciesNames.txt and Tatoosh-Taxonomy.csvTatooshNonTrophic.txtTatoosh-TaxonomyCSV file containing taxonomic information for each of the nodes used in the interaction web files for Tatoosh Island, Washington. The order of taxa in the table corresponds to the order of taxon as they appear in the interaction webs.TatooshTrophicText file containing a matrix indicating absence (0), prey (1) or consumer (-1) trophic effects of one species (across columns of the matrix) on another species (down rows of the matrix) from the middle intertidal (mussel-dominated) zone of Tatoosh Island, Washington, USA. Species names and order corresponding to matrix columns/rows are found in file TatooshSpeciesNames.txt and Tatoosh-Taxonomy.csvTatoosh Interaction WebInteraction web (trophic and non-trophic) for the middle intertidal, mussel dominated community of Tatoosh Island, Washington, provided as a matrix of positive (1), negative (-1) or no (0) interaction. Taxon identity and order are contained in Tatoosh-Taxonomy.csvTatoosh.txt