DOI: 10.5061/dryad.1g1jwsv7f
title: Data from: Prey or protection? Access to food alters individual responses to competition in black widow spiders

description: Animals influence the phenotype and reproductive success of their
 conspecifics through competitive interactions. Such effects of competition
 can alter the intensity of selection and ultimately change the rate of
 evolution. However, the magnitude of the effects of competition, and their
 evolutionary impact, should vary depending on environmental conditions and
 individual responses among competitors. We tested whether a key
 environmental variable, resource availability, affects the response to
 competition in black widow spiders by manipulating access to prey and the
 level of competition. We examined if focal spiders modify their web
 structure and aggressiveness towards prey stimuli when a competitor is
 present, and whether these responses depend on prior prey access. We also
 tested if any effects of competition vary with individual differences
 among competitors. Access to resources changed how individuals respond to
 competition. Spiders with limited access to prey were less likely to
 attack prey stimuli in the presence of a conspecific competitor than
 spiders with greater access to prey, suggesting that limiting resources
 hinders competitive responses. In contrast, all spiders built
 better-protected webs in the presence of competitors, regardless of prior
 access to prey. Crucially, these responses differed among focal spiders
 and depended on individual competitors. Our findings highlight the
 importance of environmental conditions and individual differences in
 mediating the impact of social interactions on phenotypes and eventually
 on their evolution.
description: # Data from: Prey or protection? Access to food alters individual
 responses to competition in black widow spiders
 [https://doi.org/10.5061/dryad.1g1jwsv7f](https://doi.org/10.5061/dryad.1g1jwsv7f) ## Description of the data and file structure Data, analysis script and associated files for: Ratz T, Montiglio P-O (submitted) Prey or protection? Access to food alters individual responses to competition in a black widow spider Data collected by TR. Please refer to the manuscript for data collection methods and statistical analyses. For questions or to notify the authors if any errors are identified in the data, please contact Dr. Tom Ratz ([tom.ratz@uzh.ch](mailto:tom.ratz@uzh.ch)). ### Files and variables #### File: DATA\_aggressiveness.csv **Description:** These data were used to test for effects of the food treatment (Low vs. High) and the presence of a stimulus spider on focal aggressiveness towards prey stimuli. ##### Variables * id_focal: Identity of the focal spider from 955 to 1060 * treatment:  Food treatment: restricted (low food) or ad_libitum (high food) * partner_present: Presence of a stimulus spider: present = Yes, absent = No * id_partner: Identity of the stimulus spider from 957 to 1058 * web_no: Number of the web building session from 1 to 3 * trial: Aggression trial number from 1 to 24 * trial_time: Time of the day at which the trials began: AM, PM * assay_series: Number of the series of aggression assays from 1 to 8 * distance: Distance in the web where the prey stimulus was applied: near, far, between * aggress: Aggression score from 0 to 4 #### File: DATA\_web\_structure.csv **Description:** These data were used to test for effects of the food treatment (Low vs. High) and the presence of a stimulus spider on the structure of the web built by focal spiders. ##### Variables * id_focal: Identity of the focal spider from 955 to 1060 * treatment: Experimental treatment: low, high, stimulus * web_no: Number of the web building session from 1 to 3 * web_date: Date at which the web building session began in the format yyyymmdd * weight_before: Focal body weight in grams measured before web building * partner_present: Presence of a social partner: present = Yes, absent = No * id_partner: Identity of the social partner from 955 to 1060 * weight_before_partner: Social partner's body weight in grams measured before web building * weight_after: Focal body weight in grams of the spider after web building * rel_weight_loss: Percentage of focal body weight loss b/w before–after web building * no_structural: Total number of focal structural threads counted * no_trap: Total number of focal trap threads counted * total_threads: Total number of focal vertical threads counted (i.e. structurals+traps) * web_mass_fresh: Fresh mass of the focal web in grams * web_mass_dry: Dry mass of the focal web in grams ## Code/software Annotated R script for the statistical analysis of "DATA_aggressiveness.csv" and "DATA_web_structure.csv". ## Access information Other publicly accessible locations of the data: * [https://osf.io/4hxvb/files/osfstorage](https://osf.io/4hxvb/files/osfstorage)