In this project, we want to contribute to the conceptual and methodological integration of ecology and evolutionary biology, by (1) studying the characteristics of evolutionary responses to strong selection pressures (predation, parasitism, pollution and temperature/climate change) in an ecologically sound context, taking multiple traits and multiple selection pressures as well as the presence of other species into consideration, and by (2) documenting and quantifying the occurrence of feedback loops of micro-evolution to community structure and ecosystem functioning. Our analysis of micro-evolution aims to generate a comprehensive view on the evolutionary potential and constraints in natural populations. We will therefore work on natural aquatic populations, in a multivariate context, and pay attention to micro-evolutionary and macro-evolutionary as well as ecological constraints on evolution. By explicitly considering the impact of dispersal / gene flow in our study of the feedback loop between evolutionary responses and ecological processes, our project has direct bearing on the emerging field of metacommunity ecology. More specifically, we here incorporate evolution as a process contributing to metacommunity structure. We use three model organisms: the water flea Daphnia, the three-spined stickleback Gasterosteus aculeatus, and damselfly larvae of the genera Enallagma and Lestes. Our approach involves a combination of field work, field and laboratory experiments, genetics and genomics, and modeling.