A Simple Behavioral Model Predicts the Emergence of Complex Animal Hierarchies

Abstract

Social dominance hierarchies are widespread, but little is known about the mechanisms that produce nonlinear structures. In addition to despotic hierarchies, where a single individual dominates, shared hierarchies exist, where multiple individuals occupy a single rank. In vertebrates, these complex dominance relationships are thought to develop from interactions that require higher cognition, but similar cases of shared dominance have been found in social insects. Combining empirical observations with a modeling approach, we show that all three hierarchy structures-linear, despotic, and shared-can emerge from different combinations of simple interactions present in social insects. Our model shows that a linear hierarchy emerges when a typical winner-loser interaction (dominance biting) is present. A despotic hierarchy emerges when a policing interaction is added that results in the complete loss of dominance status for an attacked individual (physical policing). Finally, a shared hierarchy emerges with the addition of a winner-winner interaction that results in a positive outcome for both interactors (antennal dueling). Antennal dueling is an enigmatic ant behavior that has previously lacked a functional explanation. These results show how complex social traits can emerge from simple behaviors without requiring advanced cognition.

The Neuropeptide Corazonin Controls Social Behavior and Caste Identity in Ants

“…1B). Besides a slight delay in the onset and peaking of dueling, these kinetics were similar to those observed upon gamergate removal from larger colonies containing workers of different ages (Sasaki et al, 2016). …”

“…Unlike most other ant species, when a Harpegnathos queen dies or becomes too old to maintain her reproductive output, some of the workers rise to replace her and take over reproductive duties, thus prolonging the life of the colony (Peeters and Holldobler, 1995). The selection of the queen’s replacements occurs by a ritualized “tournament”, during which workers engage in policing, biting, and dueling behaviors, in the attempt to re-establish a social hierarchy (Peeters et al, 2000; Penick et al, 2014; Sasaki et al, 2016). Victorious individuals activate their dormant ovaries, stop performing worker tasks, and start laying fertilized eggs.…”

An Engineered orco Mutation Produces Aberrant Social Behavior and Defective Neural Development in Ants

“…While some desist rapidly, most of those that persist in dueling become gamergates and lay eggs (Sasaki et al, 2016)(G.M., in preparation; J. Gospocic, submitted). To address whether the orco mutation affected dueling and the gamergate transition, we generated a colony with 39 randomly selected young F4 putative orco mutant ants within a setting devoid of a queen or gamergates, and tested their ability to become gamergates.…”

“…Most ant castes are established during development in diploid females, while normally, the only role for haploid males is reproduction (Hölldobler and Wilson, 1990). However, the ponerine ant species Harpegnathos saltator displays strong adult phenotypic plasticity: When a queen dies or is removed from a colony, workers compete via antennal dueling, and the most frequent duelers become reproductive gamergates (pseudoqueens) (Bonasio, 2012; Hölldobler and Wilson, 2008; Peeters et al, 2000; Sasaki et al, 2016; Yan et al, 2014). While these gamergates are not morphologically different from workers, they exhibit queen-like physiology and behavior ( e.g.…”

A practical guide for inferring reliable dominance hierarchies and estimating their uncertainty

“…Extensive theoretical efforts have been made on understanding how dominance hierarchies are formed and maintained (e.g. Dugatkin & Earley, 2004;Parker, 1974;Sasaki et al, 2016).…”