DOI: 10.5061/dryad.29p63mb
title: Data from: Spider webs, stable isotopes and molecular gut content analysis: multiple lines of evidence support trophic niche differentiation in a community of Hawaiian spiders

description: 1. Adaptive radiations are typically characterized by niche partitioning
 among their constituent species. Trophic niche partitioning is
 particularly important in predatory animals, which rely on limited food
 resources for survival. 2. We test for trophic niche partitioning in an
 adaptive radiation of Hawaiian Tetragnatha spiders, which have diversified
 in situ on the Hawaiian Islands. We focus on a community of nine species
 belonging to two different clades, one web building and the other actively
 hunting, which co-occur in wet forest on East Maui. We hypothesize that
 trophic niches differ significantly both 1) among species within a clade,
 indicating food resource partitioning, and 2) between the two clades,
 corresponding with their differences in foraging strategy. 3. To assess
 niches of the spider species, we measure a) web architecture, the
 structure of the hunting tool, and b) site choice, the physical placement
 of the web in the habitat. We then test whether differences in these
 parameters translate into meaningful differences in trophic niche by
 measuring c) stable isotope signatures of carbon and nitrogen in the
 spiders’ tissues, and d) gut content of spiders based on metabarcoding
 data. 4. We find significant interspecific differences in web architecture
 and site choice. Importantly, these differences are reflected in stable
 isotope signatures among the five web-building species, as well as
 significant isotopic differences between web-builders and active hunters.
 Gut content data also show interspecific and inter-clade differences.
 Pairwise overlaps of web architecture between species are positively
 correlated with overlaps of isotopic signature. 5. Our results reveal
 trophic niche partitioning among species within each clade, as well as
 between the web-building and actively hunting clades. Based on the
 correlation between web architecture and stable isotopes, it appears that
 the isotopic signatures of spiders’ tissues are influenced by
 architectural differences among their webs. Our findings indicate an
 important link between web structure, microhabitat preference and diet in
 the Hawaiian Tetragnatha.
description: Web architecture and
 site choice dataIncludes web
 architecture and site choice data for web-building
 spiderswebs_2013_2014.csvIsotope dataMaster spreadsheet of isotope data for all samplesisotopes_2014_2016.csvGut content data: order level of preyTable showing relative sequence read abundance of different prey orders in spider species, rarefied to 500 reads per spidergutES.csvGut content data: OTU level of preyTable showing relative sequence read abundance of different prey OTUs (97% sequence similarity) in spider species, rarefied to 500 reads per spiderotuES.csvIsotope data: controlled for elevation and yearIsotope data for samples only collected at higher elevation, and controlled for year (2014 for web-builders, 2016 for Spiny Leg spiders). Used for inter-species comparisons included in Supporting Informationisotopes_2014_2016_upper.csvIsotope data: 2014 onlyIsotope data for samples only collected in 2014. Used to test for isotopic differences between clades (web-building and Spiny Leg) when controlling for year and elevation (used in Supporting Information)isotopes_2014.csvReadMeDescribes raw data files and scripts included in data packageHypervolume scriptScript for initial analysis of spider niche data. Performs PCA on web architecture, generates the hypervolume and calculates the hypervolume overlap for web architecture and stable isotopes, and calculates beta diversity of gut contents among speciesspiders_calcOverlap.RHypervolume toolsWrapper functions written by JYL to calculate hypervolume overlap from a dataframehypervolumeTools.RNiche analysesSecond script to run for spider niche analysis, after running "spiders_calcOverlap.R". Calculates the Tukey HSD tests for each of the web architectural and isotopic variables, and tests for correlation between hypervolume overlapsspiders_analysis.RPermanova scriptScript that uses PERMANOVA to test for differences in taxonomic composition of gut contents between pairs of species, at both order and OTU level of preypermanova.RSupplementary analyses scriptUsing datasets controlled for sampling year and elevation, this script calculates the Tukey HSD tests for each of the isotopic variables within each clade (web-builders and Spiny Leg spiders). Results appear in Supporting Informationspiders_analysis_supp.RWeb photos 2013, 1 of 2Field photos of webs measured for web architecture analysisweb_photos_13_1-60.zipWeb photos 2013, 2 of 2Field photos of webs measured for web architecture analysisweb_photos_13_61-117.zipWeb photos 2014, 1 of 3Field photos of webs measured for web architecture analysisweb_photos_14_1-30.zipWeb photos 2014, 2 of 3Field photos of webs measured for web architecture analysisweb_photos_14_31-60.zipWeb photos 2014, 3 of 3Field photos of webs measured for web architecture analysisweb_photos_14_61-82.zipGut content sequence readsSequence reads for prey DNA in individual spiders used for gut content analysissequences.zip