My research aims to enhance our understanding of the dynamics of genetic, functional, ecological and evolutionary mechanisms that interactively determine past, present and future patterns of biodiversity. Evolutionary theory predicts an interactive process, whereby environmental characteristics influence genetic and phenotypic variation in natural populations, while genetic and phenotypic diversity buffer against stress and allow for adaptive evolution (Forsman et al. 2008). Accordingly, I investigate the causes of variation among individuals, populations, species and communities, as well as the consequences of genetic and phenotypic variation for the ecological success of populations and species. My research is hypothesis driven. I use a combination of methodological approaches and different model systems (insects, fishes and microorganisms). My study species differ in life-styles and occupy different environments, and have been selected because they are suitable for testing different hypotheses, and to offer opportunities to compare results and search for general patterns.