DOI: 10.5061/dryad.sqv9s4n8m
title: Host-enemy interactions provide limited biotic resistance for a range-expanding species via reduced apparent competition

description: Aim: As species’ ranges shift poleward in response to anthropogenic
 change, they may lose antagonistic interactions if they move into less
 diverse communities, fail to interact with novel populations or species
 effectively, or if ancestral interacting populations or species fail to
 shift synchronously. We leveraged a poleward range expansion in a
 tractable insect host-enemy community to uncover mechanisms by which
 altered antagonistic interactions between native and recipient communities
 contributed to “high niche opportunities” (limited biotic resistance) for
 a range-expanding insect. Location: North America, Pacific Northwest
 Methods: We created quantitative insect host-enemy interaction networks by
 sampling oak gall wasps on 400 trees of a dominant oak species in the
 native and expanded range of a range-expanding gall wasp species. We
 compared host-enemy network structure between regions. We measured traits
 (phenology, morphology) of galls and interacting parasitoids, predicting
 greater trait divergence in the expanded range. We measured function
 relating to host control and explored if altered interactions and traits
 contributed to reduced function or biotic resistance. Results: Interaction
 networks had fewer species in the expanded range and lower complementarity
 of parasitoid assemblages among host species. While networks were more
 generalized, interactions with the range-expanding species were more
 specialized in the expanded range. Specialist enemies effectively tracked
 the range-expanding host, and there was reduced apparent competition with
 co-occurring hosts by shared generalist enemies. Phenological divergence
 of enemy assemblages interacting with the range-expanding and co-occurring
 hosts was greater in the expanded range, potentially contributing to weak
 apparent competition. Biotic resistance was lower in the expanded range,
 where fewer parasitoids emerged from galls of the range-expanding host.
 Main conclusions: Changes in interactions with generalist enemies created
 high niche opportunities, and limited biotic resistance, suggesting weak
 apparent competition may be a mechanism of enemy release for
 range-expanding insects embedded within generalist enemy networks.
description: R (packages include: vegan, bipartite) 
description: This README file was generated on 2023-09-07 by Kirsten Prior GENERAL
 INFORMATION 1. Title of Dataset: Host-enemy interactions provide limited
 biotic resistance for a range-expanding species via reduced apparent
 competition 2. Author Information A. Principal Investigator Contact
 Information Name: Kirsten Prior Institution: Binghamton University
 Address: Binghamton, NY USA Email: kprior@binghamton.edu 3. Data of data
 collection: May - August 2017 4. Geographic location of data collection:
 Washington State, Vancouver Island, British Columbia 5. Information about
 funding source that supported the collection of the data: National
 Geographic Society grant (NGS-53395R-18) National Science Foundation
 (DEB1934387) SHARING/ACCESS INFORMATION 1. Licenses/restrictions placed on
 the data: CC0 1.0 Universal (CC0 1.0) Public Domain 2. Links to
 publications that cite or use the data: Prior, K. M., Jones, D. G.,
 Meadley-Dunphy, S. A., Lee, S., Milks, A. K., Daughton, S., Forbes, A. A.,
 & Powell, T. H. Q. (2023). Host–enemy interactions provide limited
 biotic resistance for a range-expanding species via reduced apparent
 competition. Diversity and Distributions, 00, 1–16.
 https://doi.org/10.1111/ddi.13763 3. Links to other publicly accessible
 locations of the data: None 4. Links/relationships to ancillary data sets:
 None 5. Was data derived from another source? No A. If yes, list
 sources(s): NA 6. Recommended citation for this dataset: Prior, K. M.,
 Jones, D. G., Meadley-Dunphy, S. A., Lee, S., Milks, A. K., Daughton, S.,
 Forbes, A. A., & Powell, T. H. Q. (2023). Data from: Host–enemy
 interactions provide limited biotic resistance for a range-expanding
 species via reduced apparent competition. Diversity and Distributions, 00,
 1–16. https://doi.org/10.1111/ddi.13763 DATA & FILE OVERVIEW 1.
 File List: A)network dataframes (folder) sc.txt rp.txt nan.txt mtz.txt
 mto.txt lmd.txt ghe.txt fl.txt cow.txt bah.txt B) sitemetrics.txt C)
 phenology\_julian dates.xlsx E) correlation.txt F) trait dataframes
 (folder) bahquant.txt cowquant.txt flquant.txt ghequant.txt lmdquant.txt
 mtoquant.txt mtzquant.txt nanquant.txt rpquant.txt scquant.txt G)
 cumparratesites.txt (datframe) 2. Relationship between files, if
 important: None 3. Additional related data collected that was not included
 in the current data package: None 4. Are there multiple versions of the
 dataset? No A. If yes, name of file(s) that was updated: NA i. Why was the
 file updated? NA ii. When was the file updated? NA
 #########################################################################
 DATA-SPECIFIC INFORMATION FOR: network dataframe (folder) 1. Variables in
 columns of matrix: parasitoid morphospecies 2. Variables in rows of
 matrix: oak gall wasp morphotypes 3. Missing data codes: None 4.
 Specialized formats or other abbreviations used: file names in the folder
 refer to study sites
 #########################################################################
 DATA-SPECIFIC INFORMATION FOR: sitemetrics.txt 1. Number of variables: 36
 2. Number of cases/rows: 10 3. Variable List: * range:
 ("native") range (Washington State, USA) or
 ("expanded") range (Vancouver Island, British Columbia, Canada)
 of Neuroterus saltatorius * site: study sites * hostrichobs: host
 morphotype richness (observed) * parrichobs: parasitoid morphospecies
 richness (observed) * websize: network size (observed host richness x
 observed parasitoid richness) * hostrichest: host morphotype richness
 (estimated, Chao 1) * parrrichest: parasitoid morphospecies richness
 (estimated, Chao 1) * estwebsize: network size (estimated host richness x
 estimated parasitoid richness) * interactobs: interaction richness
 (observed unique number of interactions between hosts and parasitoids) *
 interactest: estimated interaction richness (estimated, Chao 1 unique
 interactions between hosts and parasitoids) * htwo: H2, weighted network
 specialization * sdiversity: interaction diversity (Shannon Entropy) *
 ievenness: network interaction evenness * linkdensity: linkage density,
 weighted diversity of interactions per species * wconnect: weighted
 Connectance, linkage density divided by number of species in network *
 propspec: proportion of specialist parasitoids out of all parasitoids *
 nsad: d' weighted specialization of parasitoids interacting with
 gamic generation of N. saltatorius * nsgd: d' weighted specialization
 of parasitoids interacting with agamic generation of N. saltatorius * nsd:
 d' specialization of parasitoids interacting with both generations of
 N. saltatorius * propspecns: propportion of specialist parasitoids of N.
 saltatorius * PACnsa: potential for apparent competition from other host
 galls to N. saltatorius (agamic) * PACnsg: potential for apparent
 competition from other host galls to N. saltatorius (gamic) * PACns:
 potential for apparent competition from other host galls to N. saltatorius
 * nspar: parasitoid morphospecies richness (observed) for parasitoids
 emerged from N. saltatorius * estarnspar: parasitoid morphospecies
 richness (estimated, Chao 1) for parasitoids emerged from N. saltatorius *
 hostshared: mean number of shared host partners * parshared: mean number
 of shared parasitoid partners * wNODF: weighted nestedness * wTC: weighted
 trophic complementarity, inverse of weighted NODF * phennsg: phenological
 divergence (difference in julian date of parasitoid emergence between
 other hosts and gamic generation of N. saltatorius) * phennsa:
 phenological divergence (difference in julian date of parasitoid emergence
 between other hosts and agamic generation of N. saltatorius) * morphnsg:
 morphological divergence (difference in traits of parasitoids emerged from
 other hosts and gamic generation of N. saltatorius) * morphnsa:
 morphological divergence (difference in traits of parasitoids emerged from
 other hosts and agamic generation of N. saltatorius) 4. Missing data
 codes: None 5. Specialized formats or other abbreviations used: None
 #########################################################################
 DATA-SPECIFIC INFORMATION FOR: phenology\_julian dates.xlsx 1. Number of
 variables: 4 2. Number of cases/rows: 65 3. Variable List: * Region:
 native ("WA") or expanded ("VI") region of N.
 saltatorius * Site: study site * Cynipid ID: host gall wasp morphotypes *
 Mean Julian date: mean julian date of parasitoid attack calculated as
 julian date of when host was collected weighted by the number of
 parasitoids emerging from galls collected on that date 4. Missing data
 codes: None 5. Specialized formats or other abbreviations used: None
 #########################################################################
 DATA-SPECIFIC INFORMATION FOR: correlation.txt 1. Number of variables: 8
 2. Number of cases/rows: 10 3. Variable List: * trophiccomp: trophic
 complementarity (standardized\_z value) * netsize: network size (estimated
 host x parasitoid richness (standardized\_z value) * connect: weighted
 connectance (standardized\_zvalue) * h2: weighted network specialization
 (standardized\_zvalue) * Nsald: specialization (d') of parasitoids
 interacting with N. saltatorius (standardized\_zvalue) * NsalPAC:
 potential for apparent competition (standardized\_zvalue) * phenology:
 phenological divergence (standardized\_zvalue) * traits: trait divergence
 (standardized\_zvalue) 4. Missing data codes: None 5. Specialized formats
 or other abbreviations used: None
 #########################################################################
 DATA-SPECIFIC INFORMATION FOR: trait dataframes (folder) 1. Number of
 variables: 7 2. Number of cases/rows: variable depending on file 3.
 Variable List: * cmorphotype: host gall wasp morphotype * morphospecies:
 parasitoid morphospecies * body: body size, length of thorax and abdomen
 of parasitoids (mm) * wareac: parasitoid wing area (mm2)/ body size (mm) *
 thoraxc: thorax width (mm)/ body size (mm) * ovic: external ovipositor
 length (mm) / body size (mm) 4. Missing data codes: None 5. Specialized
 formats or other abbreviations used: "none" refers to a
 parasitoid that is present in the metanetwork but does not interact with a
 host gall at a particular site; files are named with site acronyms
 #########################################################################
 DATA-SPECIFIC INFORMATION FOR: cumparratessite 1. Number of variables: 4
 2. Number of cases/rows: 23 3. Variable List: * site: study sites in
 different years * rate: emergence rates of parasitoids from collected N.
 saltatorius galls * range: ("na") native or ("ex")
 expanded range of N. saltatorius * year: collection years -
 ("seven") 2007, ("eight") 2008,
 ("twentyone") 2021 4. Missing data codes: None 5. Specialized
 formats or other abbreviations used: None
 #########################################################################
 CODE/SOFTWARE Code is provided in a file "CODE.R" Package used:
 bipartite, vegan, labdsv, ggplot2, scales, RColorBrewer, corrplot, Rmisc,
 lme4, lmerTest, MASS