Lucon-Xiccato Tyrone
Department of Life Sciences and Biotechnology, University of Ferrara, Via L. Borsari 46, 44121, Ferrara, Italy; Department of General Psychology, University of Padova, Padova, Italy.
Behav Processes. 2019 May;162:86-89. doi: 10.1016/j.beproc.2019.02.004. Epub 2019 Feb 12.
Aquatic prey species show sophisticated mechanisms to adjust their antipredator behaviours to the level of risk, which they estimate either by direct experience with predators or from indirect indicators such as chemical alarm cues released by injured conspecifics. For instance, evidence suggests that the alarm cues of tadpoles exposed to high levels of background predation risk elicit a stronger antipredator response compared to alarm cues of tadpoles exposed to low risk. Similarly, the alarm cues of tadpoles from environments with reduced vegetation cover might cause a stronger response than alarm cues of tadpoles from environments with abundant vegetation because tadpoles suffer high predation when vegetation is scarce. I tested this hypothesis in the edible frog, Pelophylax esculentus, by comparing the response of focal tadpoles (not exposed to vegetation manipulation) to alarm cues of donor tadpoles raised from eggs in either high- or low-vegetation treatment. I also tested the alarm cues of donor tadpoles switched from high- to low-vegetation treatments and vice versa after hatching because this would enable understanding whether an eventual difference in alarm cues occurred due to the embryonic or larval environments and whether the treatments at the two developmental stages had interactive effects. Alarm cues from the low-vegetation, and thus the high-risk, treatment elicited stronger antipredator response in focal tadpoles in comparison to the alarm cues from the high-vegetation, low-risk treatment. Results from switching donor tadpoles between vegetation treatments after hatching suggested that the observed effect was due to the vegetation treatment experienced by donor tadpoles during the larval stage, with no interactive effects. Chemical alarm cues convey information about cover abundance, an environmental factor that indirectly covaries with predation risk.
水生猎物物种展现出复杂的机制，能够根据它们所估计的风险水平来调整其反捕食行为，它们通过与捕食者的直接接触经验或者诸如受伤同种个体释放的化学警报信号等间接指标来进行风险估计。例如，有证据表明，相较于处于低风险环境中的蝌蚪的警报信号，处于高背景捕食风险环境中的蝌蚪的警报信号会引发更强的反捕食反应。同样，来自植被覆盖较少环境中的蝌蚪的警报信号，可能比来自植被丰富环境中的蝌蚪的警报信号引发更强的反应，因为当植被稀缺时蝌蚪会遭受更高的捕食风险。我通过比较焦点蝌蚪（未接触植被操控）对在高植被或低植被处理中从卵孵化出的供体蝌蚪的警报信号的反应，对食用蛙（欧洲林蛙）的这一假设进行了测试。我还测试了孵化后从高植被处理转换到低植被处理以及反之亦然的供体蝌蚪的警报信号，因为这将有助于了解警报信号最终的差异是由于胚胎期还是幼体期的环境造成的，以及两个发育阶段的处理是否具有交互作用。与来自高植被、低风险处理的警报信号相比，来自低植被（即高风险）处理的警报信号在焦点蝌蚪中引发了更强的反捕食反应。孵化后在植被处理之间转换供体蝌蚪的结果表明，观察到的效应是由于供体蝌蚪在幼体阶段所经历的植被处理，不存在交互作用。化学警报信号传达了关于遮蔽物丰富度的信息，遮蔽物丰富度是一个与捕食风险间接相关的环境因素。
