Between universality and specificity: predator kairomones in aquatic predator–prey relationships

ABSTRACT Predator specific chemicals cues (so-called kairomones) are essential in shaping aquatic predator–prey interactions. While past research has largely focused on identifying these predator related kairomones, the broader question of whether predator kairomones function as universal signals (detected by many prey taxa) or as highly specific cues (recognized only by certain taxa) has received little attention. This distinction is crucial for understanding evolutionary ecology, and the response of food webs to environmental change. Universal predator kairomones can be widely emitted by predator taxa and are recognized by various prey taxa, offering a generalized warning system in dynamic ecological contexts. However, this general responsiveness of the prey may increase the risk of false alarms and unnecessary defensive responses. In contrast, specific predator kairomones are unique compounds, allowing for tailored defensive strategies in prey species but limiting adaptability to novel threats. This article integrates current knowledge of predator kairomone chemistry with the evolution of sensory detection pathways. We hypothesize that chemical communication is a mosaic of universal and specific predator kairomones and may be shaped by the phylogenetic background of the prey species. Understanding this balance is one key to predicting food web stability and adaptation under changing conditions.