Understanding the forces that shape patterns of genetic variation across the genome and how this translates into phenotypic variation is of great general and applied interest. Recent genomic studies have shown that the interaction between selection and recombination, or linked selection, can have a profound impact on levels of genetic and heritable phenotypic variation. However, so far, we know little about the general impact of linked selection on heritable variation in plants, and the factors causing variation in the type of linked selection among species remain unclear. Here, I therefore propose a project aiming to elucidate the impact of linked selection in crucifer species. The main aim of this project is to quantify the relative impact of population size and mating system on the type and strengh of linked selection. To achieve this, I will use a combination of population genomics and population genetic modeling. The results are key for a general understanding of the forces that shape genetic variation in plants.