DOI: 10.5061/dryad.2575t
title: Data from: Aggression supersedes individual oxygen demand to drive group air-breathing in a social catfish

description: 1) Group-living is widespread among animals and comes with numerous costs
 and benefits. To date, research examining group-living has focused on
 trade-offs surrounding foraging, while other forms of resource acquisition
 have been largely overlooked. 2) Air breathing has evolved in many fish
 lineages, allowing animals to obtain oxygen in hypoxic aquatic
 environments. Breathing air increases the threat of predation, so some
 species perform group air breathing, to reduce individual risk. Within
 species, air breathing can be influenced by metabolic rate as well as
 personality, but the mechanisms of group air breathing remain unexplored.
 It is conceivable that keystone individuals with high metabolic demand or
 intrinsic tendency to breathe air may drive social breathing, especially
 in hypoxia. 3) We examined social air breathing in African sharptooth
 catfish Clarias gariepinus, to determine whether individual physiological
 traits and spontaneous tendency to breathe air influence the behaviour of
 entire groups, and whether such influences vary in relation to aquatic
 oxygen availability. 4) We studied eleven groups of four catfish in a
 laboratory arena and recorded air-breathing behaviour, activity, and
 agonistic interactions at varying levels of hypoxia. Bimodal respirometry
 was used to estimate individual standard metabolic rate (SMR) and the
 tendency to utilise aerial oxygen when alone. 5) Fish took more air
 breaths in groups as compared to when they were alone, regardless of water
 oxygen content, and displayed temporally clustere air-breathing behaviour,
 consistent with existing definitions of synchronous air breathing.
 However, groups displayed tremendous variability in surfacing behaviour.
 Aggression by dominant individuals within groups was the main factor
 influencing air breathing of the entire group. There was no association
 between individual SMR, or the tendency to obtain oxygen from air when in
 isolation, and group air breathing. 6) For C. gariepinus, synchronous air
 breathing is strongly influenced by agonistic interactions, which may
 expose subordinate individuals to risk of predation. Influential
 individuals exerted an overriding effect on risk-taking by the entire
 group, for reasons independent of their physiological oxygen requirements.
 Overall, this illustrates that social context can obscure interactions
 between an individual’s physiological and behavioural traits and their
 tendency to take risks to obtain resources.
description: individual data within
 groupsThis file contains data
 for individual fish observed within group trials as described in the
 paper. Also includes metabolic rate and oxygen uptake data for each
 fish.group level
 dataThis file contains
 group-level data for each group tested at each level of oxygen
 availability. This includes metrics such as total number of attacks per
 group, as well as coefficients of dispersion for each type of behaviour
 quantified.isolated vs group
 behaviourContains behavioural
 data for each individual fish, collected while they were exposed to 100
 and 20% air saturation both alone and as part of a
 group.