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Publication
Cortisol mediates cleaner wrasse switch from cooperation to cheating and tactical deception
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Advisor(s)
Abstract(s)
Recent empirical research, mostly done on humans, recognizes that individuals' physiological state affects levels
of cooperation. An individual's internal state may affect the payoffs of behavioural alternatives, which in turn
could influence the decision to either cooperate or to defect. However, little is known about the physiology
underlying condition dependent cooperation. Here, we demonstrate that shifts in cortisol levels affect levels of
cooperation in wild cleaner wrasse Labroides dimidiatus. These cleaners cooperate by removing ectoparasites
from visiting ‘client’ reef fishes but prefer to eat client mucus, which constitutes cheating. We exogenously
administrated one of three different compounds to adults, that is, (a) cortisol, (b) glucocorticoid receptor
antagonist mifepristone RU486 or (c) sham(saline), and observed their cleaning behaviour during the following
45 min. The effects of cortisol match an earlier observational study that first described the existence of “cheating”
cleaners: such cleaners provide small clients with more tactile stimulation with their pectoral and pelvic fins,
a behaviour that attracts larger clients that are then bitten to obtain mucus. Blocking glucocorticoid receptors
led to more tactile stimulation to large clients. As energy demands and associated cortisol concentration level
shifts affect cleaner wrasse behavioural patterns, cortisol potentially offers a general mechanism for condition
dependent cooperation in vertebrates.
Description
Keywords
Cortisol Cleaner fish Cooperative levels Tactical deception Labroides dimidiatus
Citation
Hormones and Behavior, 66, 346-350
Publisher
Elsevier