Antipredator responses of three species within the species complex to two invertebrate predators.

Prey communities in natural environments face a diverse array of predators with distinct hunting techniques. However, most studies have focused only on the interactions between a single prey species and one or more predators and typically only one of many induced defense traits, which limits our understanding of the broader effects of predators on prey communities. In this study, we conducted a common garden experiment using five clones each of three species (, , and ) from the species complex to investigate the plasticity of predator-induced defenses in response to two predators in a community ecology setting. Five clones from each species were subjected to predator kairomones from two closely related invertebrate predators that are common in several European lakes, or for a duration of 10 days, and the morphological traits of body size, head size, spina size, and the presence of spinules on the ventral and dorsal carapace margins were measured. We show that among the species within this species complex there are different antipredator reactions to the invertebrate predators. The induced responses exhibited were species, trait, and predator-specific. Notably, and developed distinctive helmets as defensive mechanisms, while microdefenses were induced in and , but not in . This demonstrates that the expression of micro- and macrodefenses across species was unrelated, highlighting the possible independent evolution of microstructures as defensive modules in 's antipredator strategies. This study is the first to document both micro- and macrodefensive phenotypic plasticity in three co-occurring species within the species complex. The differences in inducible defenses may have a substantial impact on how these three species cohabit with and .