DOI: 10.5061/dryad.2fqz612v3
title: Data from: Guppies in large groups cooperate more frequently in an experimental test of the group size paradox

description: The volunteer’s dilemma, in which a single individual is required to
 produce a public good, predicts that individuals in larger groups will
 cooperate less frequently. Mechanistically, this could result from
 trade-offs between costs associated with volunteering and costs incurred
 if the public good is not produced (nobody volunteers). During predator
 inspection, one major contributor to the cost of volunteering is likely
 increased probability of predation; however, a predator also poses a risk
 to all individuals if nobody inspects. We tested the prediction that
 guppies in larger groups will inspect a predator less than those in
 smaller groups. We also predicted that individuals in larger groups would
 perceive less threat from the predator stimulus because of the protective
 benefits of larger groups (e.g. dilution). Contrary to prediction, we
 found that individuals in large groups inspected more frequently than
 those in smaller groups but (as predicted) spent less time in refuges.
 There was evidence that individuals in intermediate-sized groups made the
 fewest inspections and spent the most time in refuges, suggesting that any
 link between group size, risk and cooperation is not driven by simple
 dilution. Extensions of theoretical models that capture these dynamics
 will likely be broadly applicable to risky cooperative behaviour.
description: # Data from: Guppies in large groups cooperate more frequently in an
 experimental test of the group size paradox ## Data files
 all_tracking_data.csv: All trajectory data for each fish, giving its
 position for each frame of the video, providing a resolution of 25Hz. This
 file contains the following variables: * frame -- the frame number * X --
 the x coordinate of the fish (in cm) * Y -- the y coordinate of the fish
 (in cm) * Fish_ID -- the individual fish identification number (unique
 within but not across trials; note the ID error could not be quantified so
 data are not appropriate for personality studies without post-processing)
 * Group_size -- the group size treatment * Trial_ID -- the identification
 code for the trial all_binned_data.csv: This file contains trajectory data
 for each fish; data are aggregated (/'binned') into a 1-second
 resolution. This file contains the following variables: * Fish_ID -- the
 individual fish identification number (unique within but not across
 trials) * Second -- the time point (as a second) of the data point * X --
 the x coordinate of the fish (in cm) * Y -- the y coordinate of the fish
 (in cm) * Dist_to_model -- the distance of the fish from the closest point
 of the predator model (in cm) * Group_size -- the group size treatment *
 Trial_ID -- the identification code for the trial all_inspection_data.csv:
 This file contains individual-level data about inspection behaviour,
 specifically the number, during, and distance of inspections. This file
 contains the following variables: * Fish_ID -- the individual fish
 identification number (unique within but not across trials) * Min_dist --
 the minimum distance that the individual approached the predator (in cm) *
 Time_within_30cm -- the amount of time (in seconds) that an individual
 spent within 30cm of the predator model * Total_time -- the total time
 that the fish was visible to the tracking software (in seconds) *
 Proportion_within_30cm -- the proportion of visible time that the fish was
 within 30cm of the predator model * Group_size -- the group size treatment
 * Trial_ID -- the identification code for the trial * N_inspections -- the
 number of inspections all_inspection_times_data.csv: This file contains
 individual-level data about inspection behaviour, specifically the time an
 individual entered and left the 30cm 'inspection zone'. This
 file contains the following variables: * Trial_ID -- the identification
 code for the trial * Group_size -- the group size treatment * Fish_ID --
 the individual fish identification number (unique within but not across
 trials) * In -- a timestamp (in seconds) that the fish entered within 30cm
 of the predator model * Out -- a timestamp (in seconds) that the fish left
 the 30cm radius of the predator model * Duration -- the amount of time (in
 seconds) that the fish spent within 30cm on that occasion
 before_all_tracking_data.csv: All trajectory data for each fish before the
 introduction of the predator model, giving its position for each frame of
 the video, providing a resolution of 25Hz. This file contains the
 following variables: * frame -- the frame number * X -- the x coordinate
 of the fish (in cm) * Y -- the y coordinate of the fish (in cm) * Fish_ID
 -- the individual fish identification number (unique within but not across
 trials) * Group_size -- the group size treatment * Trial_ID -- the
 identification code for the trial before_all_binned_data.csv: This file
 contains trajectory data for each fish before the introduction of the
 predator model; data are aggregated (/'binned') into a 1-second
 resolution. This file contains the following variables: * Fish_ID -- the
 individual fish identification number (unique within but not across
 trials) * Second -- the time point (as a second) of the data point * X --
 the x coordinate of the fish (in cm) * Y -- the y coordinate of the fish
 (in cm) * Group_size -- the group size treatment * Trial_ID -- the
 identification code for the trial all_lengths_data.csv: This file contains
 data on the length of each fish in each trial used in the manuscript. This
 file contains the following variables: * Length -- the length of the fish
 (in cm) * Date -- the date of the trial (analogous to trial ID since there
 was one trial per day) all_lengths_data_updated.csv: This file contains
 data on the length of each fish in each trial. This is an updated version
 of all_lengths_data, which contained the wrong lengths for the group
 tested on 07/12 (the difference in means is ~0.01cm; within measurement
 error range). This file contains the following variables: * Length -- the
 length of the fish (in cm) * Date -- the date of the trial (analogous to
 trial ID since there was one trial per day) all_refuge_data.csv: This file
 contains data on the proportion of time that fish spent in refuges. This
 file contains the following variables: * Fish_ID -- the individual fish
 identification number (unique within but not across trials) * Total_time
 -- the number of seconds the fish is visible * Time_refuge -- the
 proportion of time spent in the refuge (not visible) * Group_size -- the
 group size treatment * Trial_ID -- the identification code for the trial *
 Phase -- whether this was before or during predator stimulus exposure *
 pool_temp -- trial pool temperature in degrees C * fish_length -- mean
 length of fish in group in cm * pool_temp_scaled -- pool_temp z-scored *
 fish_length_scaled -- fish_length z-scored * Groupsize_Phase -- group_size
 * phase interaction group * Trial_Date -- date of trial in ddmm ## Version
 changes 7th February 2025 -- Added a new file,
 all_lengths_data_updated.csv. This is an updated version of
 all_lengths_data, which contained the wrong lengths for the group tested
 on 07/12 (the difference in means is ~0.01cm; within measurement error
 range); added all_refuge_data.csv, which was missing from initial upload.