Evolution of the Cardamine pratensis (Brassicaceae) polyploid complex in Central and southeastern Europe

Recurrent polyploid formation, weak reproductive barriers among different polyploid lineages, and ecological or spatial segregation characterize the evolution of polyploid species complexes. Here we focused on uncovering the evolutionary processes that formed the Cardamine pratensis (Brassicaceae) complex in Central and south-eastern Europe. High-throughput target enrichment of low-copy nuclear genes (Hyb-Seq) was conducted to reveal genetic structure, evolutionary history and polyploid origins in this species complex. We used group-specific probes capturing over 2000 exons that were developed based on paired-end genome skim data of Cardamine parviflora and transcriptome sequences of Cardamine amara. We inferred multiple polyploid formations in the studied species, geographically structured genetic variation reflecting glacial survival and expansion from several refugia accompanied by major postglacial genetic reshuffling, as well as allopatric and ecological divergence patterns.