DOI: 10.5061/dryad.km75s
title: Data from: Determinants of parasitoid communities of willow-galling sawflies: habitat overrides physiology, host plant, and space

description: Studies on the determinants of plant–herbivore and herbivore–parasitoid
 associations provide important insights into the origin and maintenance of
 global and local species richness. If parasitoids are specialists on
 herbivore niches rather than on herbivore taxa, then alternating escape of
 herbivores into novel niches and delayed resource tracking by parasitoids
 could fuel diversification at both trophic levels. We used DNA barcoding
 to identify parasitoids that attack larvae of seven Pontania sawfly
 species that induce leaf galls on eight willow species growing in
 subarctic and arctic–alpine habitats in three geographic locations in
 northern Fennoscandia, and then applied distance- and model-based
 multivariate analyses and phylogenetic regression methods to evaluate the
 hierarchical importance of location, phylogeny and different galler niche
 dimensions on parasitoid host use. We found statistically significant
 variation in parasitoid communities across geographic locations and willow
 host species, but the differences were mainly quantitative due to
 extensive sharing of enemies among gallers within habitat types. By
 contrast, the divide between habitats defined two qualitatively different
 network compartments, because many common parasitoids exhibited strong
 habitat preference. Galler and parasitoid phylogenies did not explain
 associations, because distantly related arctic–alpine gallers were
 attacked by a species-poor enemy community dominated by two parasitoid
 species that most likely have independently tracked the gallers’
 evolutionary shifts into the novel habitat. Our results indicate that
 barcode- and phylogeny-based analyses of food webs that span forested vs.
 tundra or grassland environments could improve our understanding of
 vertical diversification effects in complex plant–herbivore–parasitoid
 networks.
description: Barcode sequences of
 reared parasitoid reference specimensCOI barcode sequences of
 72 reared adult parasitoid reference specimens that were used to identify
 larval parasitoids based on their barcodes.Barcode_sequences_of_reared_parasitoid_reference_specimens.nexBarcode sequences of parasitoid larvaeCOI barcode sequences of 561 parasitoid larvae collected from galls induced by Pontania sawfliesBarcode_sequences_of_parasitoid_larvae.nexParasitoid numbers in Pontania population-level samplesNumbers of parasitoid larvae (identified by COI barcodes) representing each of 14 parasitoid species in 22 Pontania leaf-galler community samples.Parasitoid_numbers_raw_data.xlsxCommands and data for GLM analyses in mvabundCombined text file containing commands and data used for the model-based analyses of the effects of host (galler and willow species) and location on parasitism using the mvabund package in R.Commands_and_data_for_GLM_analyses_in_mvabund.txtCommands and data for test of phylogenetic effectsCombined text file containing commands and data used for testing the effects of galler and parasitoid phylogenies on proportional species-level parasitism as described in Ives & Godfray (2006).Commands_and_data_for_test_of_phylogenetic_effects.txt