PREMISE: Although Boechera (Boechereae, Brassicaceae) has become a plant model system for both ecological genomics and evolutionary biology, all previous phylogenetic studies have had limited success in resolving species relationships within the genus. The recent effective application of sequence data from target enrichment approaches to resolve the evolutionary relationships of several other challenging plant groups prompted us to investigate their usefulness in Boechera and Boechereae. METHODS: To resolve the phylogeny of Boechera and closely related genera, we utilized the Hybpiper pipeline to analyze two combined bait sets: Angiosperms353, with broad applicability across flowering plants; and a Brassicaceae-specific bait set designed for use in the mustard family. Relationships for 101 samples representing 81 currently recognized species were inferred from a total of 1114 low-copy nuclear genes using both supermatrix and species coalescence methods. RESULTS: Our analyses resulted in a well-resolved and highly supported phylogeny of the tribe Boechereae. Boechereae is divided into two major clades, one comprising all western North American species of Boechera, the other encompassing the eight other genera of the tribe. Our understanding of relationships within Boechera is enhanced by the recognition of three core clades that are further subdivided into robust regional species complexes. CONCLUSIONS: This study presents the first broadly sampled, well-resolved phylogeny for most known sexual diploid Boechera. This effort provides the foundation for a new phylogenetically informed taxonomy of Boechera that is crucial for its continued use as a model system.

CEITEC Central European Institute of Technology Masaryk University Kamenice 5 Brno 625 00 Czech Republic

Department of Biology Botany University of Osnabrück Barbarastraße 11 Osnabrück D 49076 Germany

Department of Biology Duke University Durham 27708 North Carolina USA

Department of Biology New Mexico State University Las Cruces New Mexico USA

Department of Experimental Biology Faculty of Science Masaryk University Kamenice 5 Brno 625 00 Czech Republic

Institute of Biology Leiden Plant Sciences Leiden University Sylviusweg 72 2333 BE Leiden The Netherlands

National Centre for Biomolecular Research Faculty of Science Masaryk University Kamenice 5 Brno 625 00 Czech Republic

Naturalis Biodiversity Center P O Box 9517 Leiden 2300 RA The Netherlands

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