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性担忧与警觉性提升。该情绪状态在脊椎动物中已有广泛报道，近年来在少数无脊椎动物物种中也有相关记录。然而，其进化适应度价值仍尚不明确。本研究以端足类甲壳动物（amphipod crustacean）为研究对象，以电击作为厌恶性刺激，并结合药理学实验，探究了类焦虑行为及其相关后果。在穴居钩虾（Gammarus fossarum）中，电击诱导产生的类焦虑状态会通过在无捕食风险情境下增加隐蔽行为得以体现，由此表明该行为反应具有普遍性。电击次数的增加不仅提升了生物对隐蔽场所的使用频次，还延缓了行为恢复进程。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）——进行处理，可削弱电击引发的行为效应。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，在微宇宙实验中可提升捕食压力下的存活率。本研究证实了从进化视角开展焦虑研究的价值，并呼吁后续研究深入探究抵消本研究中所证实的、提升焦虑水平所带来的生存益处的相关成本。