DOI: 10.5061/dryad.4q78p
title: Data from: Relative impacts of environmental variation and evolutionary history on the nestedness and modularity of tree-herbivore networks.

description: Nestedness and modularity are measures of ecological networks whose
 causative effects are little understood. We analyzed antagonistic
 plant–herbivore bipartite networks using common gardens in two contrasting
 environments comprised of aspen trees with differing evolutionary
 histories of defence against herbivores. These networks were tightly
 connected owing to a high level of specialization of arthropod herbivores
 that spend a large proportion of the life cycle on aspen. The gardens were
 separated by ten degrees of latitude with resultant differences in abiotic
 conditions. We evaluated network metrics and reported similar connectance
 between gardens but greater numbers of links per species in the northern
 common garden. Interaction matrices revealed clear nestedness, indicating
 subsetting of the bipartite interactions into specialist divisions, in
 both the environmental and evolutionary aspen groups, although nestedness
 values were only significant in the northern garden. Variation in plant
 vulnerability, measured as the frequency of herbivore specialization in
 the aspen population, was significantly partitioned by environment (common
 garden) but not by evolutionary origin of the aspens. Significant values
 of modularity were observed in all network matrices. Trait-matching
 indicated that growth traits, leaf morphology, and phenolic metabolites
 affected modular structure in both the garden and evolutionary groups,
 whereas extra-floral nectaries had little influence. Further examination
 of module configuration revealed that plant vulnerability explained
 considerable variance in web structure. The contrasting conditions between
 the two gardens resulted in bottom-up effects of the environment, which
 most strongly influenced the overall network architecture, however, the
 aspen groups with dissimilar evolutionary history also showed contrasting
 degrees of nestedness and modularity. Our research therefore shows that,
 while evolution does affect the structure of aspen–herbivore bipartite
 networks, the role of environmental variations is a dominant constraint.
description: README:
 OverviewThis package contains a
 copy of the data files used for this paper.Genotype_DGC_Latitude_LongitudeDetails of the northern, southern (or central) DGC (where available), and the original latitude and longitude of the trees cloned and planted in the common gardens.Southern_garden_all_genotypes_abundancesHerbivorous arthropod morphospecies (numbered as they appear in Table 2 of the manuscript) as mean counts on aspen genotypes in the southern common garden.Northern_garden_all_genotypes_abundancesHerbivorous arthropod morphospcies (numbered as they appear in Table 2 of the manuscript) as mean counts on aspen genotypes in the northern common garden.Northern_garden_trait-matching_all_genotypesPhenotypic data for all genotypes in the northern garden: latitude of genotype origin, tree height, tree diameter, bud flush date, bud set date, active growth period, mean individual leaf area, mean specific leaf area, mean petiole length, the proportion of leaves bearing extra-floral nectaries (EFNs), foliar total phenolics, foliar condensed tannins, and the paired difference index based on arthropod herbivore counts. Module is the module number to which each genotype was assigned.Northern_garden_trait-matching_South_DGCPhenotypic data for aspen genotypes comprising the South DGC in the northern garden: latitude of genotype origin, tree height, tree diameter, bud flush date, bud set date, active growth period, mean individual leaf area, mean specific leaf area, mean petiole length, the proportion of leaves bearing extra-floral nectaries (EFNs), foliar total phenolics, foliar condensed tannins, and the paired difference index based on arthropod herbivore counts. Module is the module number to which each genotype was assigned.Northern_garden_trait-matching_North_DGCPhenotypic data for aspen genotypes comprising the North DGC in the northern garden: latitude of genotype origin, tree height, tree diameter, bud flush date, bud set date, active growth period, mean individual leaf area, mean specific leaf area, mean petiole length, the proportion of leaves bearing extra-floral nectaries (EFNs), foliar total phenolics, foliar condensed tannins, and the paired difference index based on arthropod herbivore counts. Module is the module number to which each genotype was assigned.Southern_garden_trait-matching_all_genotypesPhenotypic data for all genotypes in the southern garden: latitude of genotype origin, tree height, tree diameter, bud flush date, bud set date, active growth period, mean individual leaf area, mean specific leaf area, mean petiole length, the proportion of leaves bearing extra-floral nectaries (EFNs), foliar total phenolics, foliar condensed tannins, and the paired difference index based on arthropod herbivore counts. Module is the module number to which each genotype was assigned.Southern_garden_trait-matching_North_DGCPhenotypic data for aspen genotypes comprising the North DGC in the southern garden: latitude of genotype origin, tree height, tree diameter, bud flush date, bud set date, active growth period, mean individual leaf area, mean specific leaf area, mean petiole length, the proportion of leaves bearing extra-floral nectaries (EFNs), foliar total phenolics, foliar condensed tannins, and the paired difference index based on arthropod herbivore counts. Module is the module number to which each genotype was assigned.Southern_garden_trait-matching_South_DGCPhenotypic data for aspen genotypes comprising the South DGC in the southern garden: latitude of genotype origin, tree height, tree diameter, bud flush date, bud set date, active growth period, mean individual leaf area, mean specific leaf area, mean petiole length, the proportion of leaves bearing extra-floral nectaries (EFNs), foliar total phenolics, foliar condensed tannins, and the paired difference index based on arthropod herbivore counts. Module is the module number to which each genotype was assigned.