One major challenge in biology is to understand how microevolutionary processes generate macroevolutionary patterns. My research group studies plants and plant-feeding insects, as phylogenetic studies indicate that speciation in these groups is driven by divergent specialization in traits of importance for the species interaction. Here, we focus on the evolution of floral scent, a complex trait of crucial importance for plant-insect interactions. After several years of eco-evolutionary studies in a plant model system, Arabis alpina, we are applying a combination of field studies, crossing experiments, chemical ecology and genomics to investigate how floral scent is diversified in natural populations. In particular, we test how a striking floral scent variation among populations relates to geographic variation in their interaction with insects. The available A. alpina reference genome allows us to couple ecological surveys, field transplant experiments and genomic studies aimed at reconstructing the phylogeographic background to floral scent variation. Toward that end, we have re-sequenced ten individuals from each of six different natural populations of Arabis alpina. These are located in Italy and Greece, where A. alpina is self-incompatible and thus completely dependent on insect pollination for reproduction, and where previous studies have shown that the floral scent bouquet can vary extensively even among populations located only a few tenths of kilometres apart. The genomic data obtained were first analyzed in a master’s thesis and later presented also as part of a doctoral thesis, testing the hypothesis that floral scent differentiation is driven by local adaptation rather than genetic drift or population history. These initial analyses are part of a manuscript in preparation for being submitted within the next few months. There are, however, still many analyses to be done, for example to identify candidate regions that explain the presence and absence of particular floral scent phenotype of the analysed individuals. These analyses will be included in a future manuscript. Now, we have launched the second step of the project, which is to resequence a set of segregating F2-individuals, produced in crosses between highly scented A. alpina individuals, and “natural knockouts” that emit no, or very little, detectable floral scent. The F1-and F2-generations are now extracted and will soon be sent off to sequencing. We will also perform a transcriptomics study to quantify the importance of gene expression variation for floral scent divergence. Collectively, this means that we will generate new large dataset in need of storage resources. The project is supported by grants from the Swedish Research Council to Magne Friberg and from the National Science Foundation of the USA and the Erik Philip Sörensson Foundation to Katherine Eisen, who is a new postdoc in the project. These grants allow us during next year to add also gene expression analyses of genes involved in the floral scent production. Collectively, these studies address several unresolved questions about how complex traits like floral scent are molded and diversified through selection from each local ecological network of interacting insects.