Data from: Anxiety-like behaviour increases safety from fish predation in an amphipod crustacea

Anxiety is an emotional state generally expressed as sustained apprehension of the environment and elevated vigilance. It has been widely reported in vertebrates, and, more recently, in a few invertebrate species. However, its fitness value remains elusive. We investigated anxiety-like behaviour and its consequences in an amphipod crustacean, using electric-shock as an aversive stimuli, and pharmacological assays. Anxiety-like state induced by electric shocks in Gammarus fossarum was expressed through increased sheltering behaviour in absence of predation risk, thereby showing the pervasive nature of such behavioural response. Increasing the number of electric shocks both increased refuge use and delayed behavioural recovery. The behavioural effect of electric shock was mitigated by pre-treatment with LY354740, a metabotropic glutamate receptor group II/III agonist. Importantly, we found that this modulation of decision making under anxiety-like state resulted in an increased survival to predation in microcosm experiments. This study confirms the interest in taking an evolutionary view to the study of anxiety, and calls for further investigation on the costs counterbalancing the survival benefit of an elevated anxiety level evidenced here.

焦虑是一种情绪状态，通常表现为对环境的持续忧虑与警戒水平升高。该情绪状态已在脊椎动物中被广泛报道，近年来也在少数无脊椎动物物种中有所记录。然而，其进化适合度价值仍不明朗。本研究以端足类甲壳动物为研究对象，采用电击作为厌恶性刺激（aversive stimuli），结合药理学实验（pharmacological assays），探究了类焦虑行为（anxiety-like behaviour）及其相关后果。在穴居钩虾（Gammarus fossarum）中，电击诱导的类焦虑状态表现为：在无捕食风险的情境下，个体的隐蔽行为显著增加，从而印证了该类行为反应的普遍性。电击次数的增加不仅提升了个体的避难行为频次，还延缓了其行为恢复速度。预先施用代谢型谷氨酸受体II/III激动剂（metabotropic glutamate receptor group II/III agonist）LY354740，可缓解电击所引发的行为效应。尤为重要的是，本研究发现，在类焦虑状态下对决策过程的这种调控，可在微宇宙实验（microcosm experiments）中提升个体的捕食存活概率。本研究证实了从进化视角开展焦虑研究的价值，并呼吁后续研究探索抵消本研究中所证实的、焦虑水平升高所带来的存活益处的相关成本。