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（anxiety）是一种情绪状态，通常表现为对环境的持续性警觉不安且警戒水平升高。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类群中被证实存在。然而，其进化适合度价值仍难以阐明。我们以端足类甲壳动物（amphipod crustacean）为研究对象，采用电击作为厌恶性刺激（aversive stimuli）并结合药理学实验（pharmacological assays），探究了类焦虑行为（anxiety-like behaviour）及其相关后果。在霍夫钩虾（Gammarus fossarum）中，电击诱导的类焦虑状态表现为无捕食风险时个体的避蔽行为增多，这表明该类行为反应具有普遍性。增加电击次数，不仅会提升个体的栖身避险频次，还会延迟其行为恢复进程。预先使用LY354740——一种代谢型谷氨酸受体II/III激动剂（metabotropic glutamate receptor group II/III agonist）——处理，可缓解电击引发的行为效应。重要的是，我们发现这种对类焦虑状态下决策过程的调控，在微宇宙实验（microcosm experiments）中可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学术价值，并呼吁后续进一步探究抵消本研究中所发现的高焦虑水平带来的存活益处的相关代价。