Genomic studies of adaptive evolution in outcrossing Arabidopsis species

•Outcrossers are powerful models of adaptation with clear advantages over selfers.•Arabidopsis arenosa is the subject of many of the most recent large-scale studies.•Recent studies focused on adaptation to both environmental and intracellular challenge.

Large-scale population genomic approaches have very recently been fruitfully applied to the Arabidopsis relatives Arabidopsis halleri, A. lyrata and especially A. arenosa. In contrast to A. thaliana, these species are obligately outcrossing and thus the footprints of natural selection are more straightforward to detect. Furthermore, both theoretical and empirical studies indicate that outcrossers are better able to evolve in response to selection pressure. As a result, recent work in these species serves as a paradigm of population genomic studies of adaptation both to environmental as well as intracellular challenges.