The effects of cross- and self-fertilization have attracted the interest of many generations of biologists, including Darwin. However, although about 40% of flowering plants have intermediate outcrossing rates and are mixed mating, most population genetic studies have only contrasted highly selfing and highly outcrossing species. Our current picture of the population genomic effects of mating system variation thus remains incomplete. Indeed, while recent population genetic theory predicts that mixed mating populations can avoid the negative genomic effects of high selfing rates and benefit from more efficient selection on recessive mutations, few studies have tested these predictions. The Alpine rock-cress Arabis alpina offers an ideal opportunity to study the effects of mixed mating, because it harbors both self-incompatible outcrossing, mixed mating and highly self-fertilizing populations. Here, we aim to take full advantage of this system to contrast the signature of natural selection on genomic patterns of variation and repeat content across the full range of mating systems, including mixed mating.