Unavoidable limits on group size in a body size-based linear hierarchy

Ang, Tzo Zen; Manica, Andrea

doi:10.1093/beheco/arq062

Cited by 40 publications

(36 citation statements)

References 45 publications

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“…First, if the stability of dominance hierarchies depends on individual recognition [21], then larger groups may be less likely to maintain a stable hierarchy. Second, if dominance relations are the probabilistic outcomes of preexisting asymmetries in competitive ability (known as the 'prior attributes' model: [22]), increase in group size will decrease the average competitive asymmetry between pairs of individuals, making linear hierarchies less likely [9,23]. In addition to group size, other socioecological differences across species or higher-level taxonomic groups could drive variation in the structure of dominance hierarchies [24].…”

Section: Introductionmentioning

confidence: 99%

The network motif architecture of dominance hierarchies

Shizuka

McDonald

2015

J. R. Soc. Interface.

101

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The widespread existence of dominance hierarchies has been a central puzzle in social evolution, yet we lack a framework for synthesizing the vast empirical data on hierarchy structure in animal groups. We applied network motif analysis to compare the structures of dominance networks from data published over the past 80 years. Overall patterns of dominance relations, including some aspects of non-interactions, were strikingly similar across disparate group types. For example, nearly all groups exhibited high frequencies of transitive triads, whereas cycles were very rare. Moreover, pass-along triads were rare, and double-dominant triads were common in most groups. These patterns did not vary in any systematic way across taxa, study settings (captive or wild) or group size. Two factors significantly affected network motif structure: the proportion of dyads that were observed to interact and the interaction rates of the top-ranked individuals. Thus, study design (i.e. how many interactions were observed) and the behaviour of key individuals in the group could explain much of the variations we see in social hierarchies across animals. Our findings confirm the ubiquity of dominance hierarchies across all animal systems, and demonstrate that network analysis provides new avenues for comparative analyses of social hierarchies.

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Section: Introductionmentioning

confidence: 99%

The network motif architecture of dominance hierarchies

Shizuka

McDonald

2015

J. R. Soc. Interface.

101

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“…Therefore the next challenge for our understanding of conflict resolution, and patterns of social organization more broadly, requires attempts to understand variation in size ratios in natural populations (e.g. Ang and Manica, 2010b;Wong 2011). …”

Section: Discussionmentioning

confidence: 99%

“…In particular, investigating size ratio variation both between species and between populations of a given species would be helpful, as would detailed investigations into the causes and consequences of variation in both actual and threshold size ratios (Buston and Cant 2006;Wong et al 2007;Ang and Manica 2010b;Wong 2011).…”

Section: Discussionmentioning

confidence: 99%

The four elements of within-group conflict in animal societies: an experimental test using the clown anemonefish, Amphiprion percula

Wong

Uppaluri

Medina

et al. 2016

Behav Ecol Sociobiol

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Conflicts of interest are part and parcel of living in a social group, yet actual conflict can be rare in established groups. Within limits, individuals can maximize the benefits of group living by resolving conflict with other group members. Thus, understanding what causes conflict, what determines its outcome, and how it is resolved holds the key to understanding the evolution and maintenance of sociality. Here, we investigate these questions using the clown anemonefish Amphiprion percula. Clownfish live in groups composed of a breeding pair and zero to four non-breeders that queue for breeding positions. Within groups, there is potential conflict over rank yet actual conflict is very rare. We staged contests in aquaria between pairs of nonbreeding individuals over access to a key resource (an anemone), analogous to contests that would occur at the onset of group formation in the wild. The initial size ratio between individuals tended to predict the intensity, and predicted the outcome and resolution of conflict: conflict intensity was greater when individuals were more similar in size; the probability of the smaller individual winning was greater when individuals were more similar in size; and the loser of the contest grew less than the winner when individuals were more similar in size. These results provide a critical test of foundational assumptions upon which our understanding of clownfish and other fish societies has been built. More generally, the results show that one of the simplest and most effective ways for animals to resolve conflict is to modify the phenotype that triggers conflict. causes conflict, what determines its outcome and how it is resolved holds the key to understanding the evolution and maintenance of sociality. Here, we investigate these questions using the clown anemonefish Amphiprion percula. Clownfish live in groups composed of a breeding pair and zero to four non-breeders that queue for breeding positions. Within groups, there is potential conflict over rank yet actual conflict is very rare. We staged contests in aquaria between pairs of non-breeding individuals over access to a key resource (an anemone), analogous to contests that would occur at the onset of group formation in the wild. The initial size ratio between individuals predicted the intensity, outcome and resolution of conflict: conflict intensity was greater when individuals were more similar in size; the probability of the smaller individual winning was greater when individuals were more similar in size; and the loser of the contest grew less than the winner when individuals were more similar in size. These results provide a critical test of foundational assumptions upon which our understanding of clownfish and other fish societies has been built. More generally, the results show that one of the simplest and most effective ways for animals to resolve conflict is to modify the phenotype that triggers conflict.

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“…Juveniles were not considered as subordinates in this categorisation. We had previously demonstrated that if group members had home ranges that were unusually spatially segregated from each other, lowered encounter rates could mitigate the effect of group members on each other’s behaviour (Ang & Manica 2010a,c). Therefore, to avoid any effect of subordinate presence being obscured by spatial segregation, from our observational data, we excluded the groups which were highly spatially segregated, with an average overlap of adjacently ranked female home ranges below 5% (for further details see Ang & Manica 2010a,c).…”

Section: Methodsmentioning

confidence: 99%

Effect of the Presence of Subordinates on Dominant Female Behaviour and Fitness in Hierarchies of the Dwarf Angelfish Centropyge bicolor

Ang

Manica

2011

Ethology

Self Cite

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In many hierarchical animal societies, dominant individuals control group membership owing to their power to evict subordinates. In such groups, the presence of subordinates, and therefore group stability, is continually dependent on subordinates being tolerated by dominants. The dominant decision to tolerate or evict is, in turn, dependent on the costs and benefits to dominants of subordinate presence. We investigated the effect of subordinate presence on dominants in the female dominance hierarchy of the dwarf angelfish Centropyge bicolor, using both observations of natural groups and experimental removals of subordinates. We found that the presence of subordinates had no effect on dominant access to resources, as measured by dominant foraging rates and home range areas, nor on dominant fitness, as measured by growth rates and spawning frequencies. Our results suggest that the presence of subordinates has a neutral effect on the current fitness of dominants, so that dominants have no great incentive to evict subordinates. We discuss the possibility that tolerance of subordinates might be further explained by considering future fitness, as dominant females in these haremic protogynous angelfish stand to inherit the male position, whereupon subordinate females change from potential competition to useful mates.

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Unavoidable limits on group size in a body size-based linear hierarchy

Cited by 40 publications

References 45 publications

The network motif architecture of dominance hierarchies

The network motif architecture of dominance hierarchies

The four elements of within-group conflict in animal societies: an experimental test using the clown anemonefish, Amphiprion percula

Effect of the Presence of Subordinates on Dominant Female Behaviour and Fitness in Hierarchies of the Dwarf Angelfish Centropyge bicolor

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