Soares Marta C, Cardoso Sónia C, Grutter Alexandra S, Oliveira Rui F, Bshary Redouan
CIBIO, Centro de Investigação em Biodiversidade e Recursos Genéticos, Universidade do Porto, Campus Agrário de Vairão, Vairão 4485-661, Portugal.
Unidade de Investigação em Eco-Etologia, ISPA-Instituto Universitário, Lisboa, Portugal.
Horm Behav. 2014 Jul;66(2):346-50. doi: 10.1016/j.yhbeh.2014.06.010. Epub 2014 Jun 18.
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 45min. 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.
近期主要针对人类开展的实证研究认识到，个体的生理状态会影响合作水平。个体的内部状态可能会影响行为选择的收益，进而可能影响合作或背叛的决策。然而，对于依赖条件的合作背后的生理机制却知之甚少。在此，我们证明皮质醇水平的变化会影响野生裂唇鱼（Labroides dimidiatus）的合作水平。这些清洁鱼通过清除前来“客户”礁鱼身上的体外寄生虫来进行合作，但它们更喜欢吃掉客户的黏液，这构成了欺骗行为。我们对成年清洁鱼外源施用三种不同化合物中的一种，即（a）皮质醇、（b）糖皮质激素受体拮抗剂米非司酮RU486或（c）假处理（生理盐水），并在接下来的45分钟内观察它们的清洁行为。皮质醇的作用与一项早期观察性研究相符，该研究首次描述了“欺骗”清洁鱼的存在：这类清洁鱼会用胸鳍和腹鳍为小客户提供更多触觉刺激，这种行为会吸引更大的客户，然后清洁鱼会咬它们以获取黏液。阻断糖皮质激素受体会导致对大客户有更多的触觉刺激。由于能量需求和相关皮质醇浓度水平的变化会影响裂唇鱼的行为模式，皮质醇可能为脊椎动物依赖条件的合作提供了一种普遍机制。
