Tight and prolonged associations between organisms of different species are prevalent in nature. Such symbiotic relationships can range from mutualistic (both species benefit) to parasitic (one species benefits at the expense of the other) and play a crucial role in the eco-evolutionary dynamics of populations, communities and entire ecosystems. Despite the importance of symbioses in natural systems, symbiosis research is still in its infancy. At EPB, we investigate symbioses from several perspectives and using a variety of systems, including Archaea, nematodes, water fleas and mycorrhizal fungi, using omics techniques, experimental evolution, and theoretical modelling.