Date of Award


Publication Type

Master Thesis

Degree Name



Biological Sciences

First Advisor

Higgs, Dennis


Aggression, Behaviour, Dominance, Fish, Hormone expression




Exploration of the mechanisms underlying conflict resolution has been key to our understanding of the dynamics driving the formation and organization of complex animal societies. This thesis examines the role of aggression and individual variation on dominance hierarchies and the correlates of expression of cortisol, 11-ketotestosterone, and testosterone on individual social status in novel size-matched Amphiprion ocellaris dominance hierarchies. Here, I report that greater aggressiveness relays higher dominance status during hierarchy establishment, as well as during experimental recruitment of highly aggressive smaller individuals into established groups. Additionally, I show that cortisol expression profiles are related to social status in both unstable and stable hierarchies, with top-ranked dominants and lowest-ranked subordinates demonstrating stress of dominance and subordination respectively. These results offer a contrasting elucidation to the size-based hierarchy hypothesis typically implicated in modulating anemonefish social structures and provide evidence indicating that dominance may be driven by variation in individual aggressiveness and stress profiles.