The project deals with the ecology and evolution of predator- induced defenses (PIDs) in aquatic invertegrates. PIDs are pheno- typic changes (morphology, behaviour and/or life history) induced directly by cues associated with predators. PIDs will be studied under conflicting environmental pressures (e.g.,time constraints) and internal conditions (e.g. hunger level). The variation in the use of PIDs by prey species and populations gives the opportunity to study macro- as well as micro-evolution of PIDs, including local adaptation. Prey populations that are locally adapted to a certain predator environment will differ in their use of PIDs, and this will create differences in the strength of direct and indirect interactions with other species in the community. Ultimately, this may result in differences in the dynamics of local food webs.