Neophobia, the fear response of organisms towards novel cues, is a phenotypically plastic trait that manifests among prey that experience uncertain, often high levels of risk. Prey that find themselves in uncertain or highly variable risk environments over ecological and evolutionary time could benefit from reducing the costs associated with ‘making a bad decision’ when they detect novel or unknown predatory threat. Hence, understanding ecological uncertainty in the context of prey decision making is of key interest. While ecological uncertainty remains a poorly defined concept, the degree of uncertainty experienced by prey, and by extension neophobia, should be influenced by the predictability of risk. Here, we test whether prey exposed to the same overall level of predation risk exhibit stronger neophobic responses towards a standardized novel cue when they experience the risk in an unpredictable versus predicable manner. Northern red-bellied dace, Chrosomus eos, exposed to conspecific alarm cues (risk cue) over a 3-day period exhibited a stronger intensity of neophobia than those exposed to low-level risk. However, if the alarm cues were presented as three exposures ranging in volume, the dace exhibited stronger neophobic responses compared to dace exposed to three equal exposures per day. Similarly, our second experiment showed that dace exposed over 3 days to elevated risk at random versus consistent times each day had stronger neophobic response under the random schedule. Combined, our results demonstrate that the degree of predictability of risk is a critical factor determining uncertainty and neophobia exhibited by prey populations.

中文翻译：

---

不可预测的风险加剧了北方红腹鲱鱼的恐新症

Neophobia，生物体对新线索的恐惧反应，是一种表型可塑性特征，表现在经历不确定的、通常是高风险水平的猎物中。在生态和进化过程中发现自己处于不确定或高度可变的风险环境中的猎物可以从减少与“做出错误决定”相关的成本中受益，当它们检测到新的或未知的掠夺性威胁时。因此，在猎物决策的背景下理解生态不确定性是关键。虽然生态不确定性仍然是一个定义不明确的概念，但猎物所经历的不确定性程度，以及扩展的恐新症，应该受到风险可预测性的影响。这里，我们测试暴露于相同总体捕食风险水平的猎物，当它们以不可预测与可预测的方式经历风险时，是否对标准化的新线索表现出更强的恐惧反应。在 3 天内暴露于同种警报线索（风险线索）的北方红腹鲇鱼 Chrosomus eos 表现出比暴露于低水平风险的人更强的恐新症强度。然而，如果警报提示以体积不同的 3 次暴露呈现，则与每天暴露于 3 次等量暴露的 dace 相比，dace 表现出更强的新恐惧反应。同样，我们的第二个实验表明，在随机时间表下，每天随机暴露于高风险环境中超过 3 天的鲱鱼具有更强的恐新症反应。结合，