Investigating the underlying mechanisms of diversification and adaptation is central to understanding how organisms can adapt to new environments, e.g. newly emerging pathogens or novel conditions caused by climate change, and to conserve biodiversity. For instance, we aim at understanding how cooperation or competition between organisms, hybridization between species, diversification of molecular pathways, and epigenetic processes contribute to adaptation. While questions relating to this topic have been central in evolutionary biology for decades, it has been difficult to study them at the molecular level. The recent advances of the genomic revolution now allow us to study the molecular basis of adaptive evolution as it has become possible to obtain the required genome-wide polymorphism data in both laboratory and natural populations. Thus, the spatial and temporal changes of (epi)allele frequencies – or Evolution in Action – can be identified in organisms exposed to selection in their natural or experimental environments.