Damage, digestion, and defense: The roles of alarm cues and kairomones for inducing prey defenses.

Inducible defences are widely used for studying phenotypic plasticity, yet frequently we know little about the cues that induce these defences. For aquatic prey, defences are induced by chemical cues from predators (kairomones) and injured prey (alarm cues). Rarely has anyone determined the separate and combined effects of these cues, particularly across phylogenetically diverse prey types. We examined how tadpoles (Hyla versicolor) altered their defences when 10 different prey were either crushed by hand or consumed by predators. Across all prey types, crushing induced only a subset of the defences induced by consumption. Consuming vs. crushing produced additive responses for behaviour but synergistic responses for morphology and growth. Moreover, we discovered the first extensive evidence that prey responses to different alarm cues depends on prey phylogeny. These results suggest that the amount of information available to the prey affects both the quantitative and qualitative nature of the defended phenotype.

诱导防御(inducible defences)被广泛应用于表型可塑性(phenotypic plasticity)的相关研究，但学界往往对触发此类防御的信号因子仍缺乏深入了解。对于水生猎物而言，其防御反应可由两类化学信号触发：一类来自捕食者的利它素(kairomones)，另一类来自受伤猎物的报警信号(alarm cues)。此前极少有研究明确这两类信号各自及联合作用的效应，尤其是在系统发育多样的猎物类群中。本研究设置了"手工碾碎猎物"与"捕食者捕食猎物"两种处理，以此探究10种不同猎物分别作用下，灰树蛙(Hyla versicolor)的防御反应如何发生改变。针对所有猎物类群，手工碾碎处理仅能诱导出捕食过程所触发的部分防御反应。与碾碎处理相比，捕食处理对猎物的行为响应呈现加性效应，而对形态与生长响应则呈现协同效应。此外，本研究首次提供了大量实证证据，表明猎物对不同报警信号的响应依赖于其自身的系统发育背景。上述研究结果表明，猎物可获取的信息总量，会同时影响防御型表型(defended phenotype)的量化特征与质化特征。