Taxonomy and phylogeny of Cardamine (Brassicaceae) species endemic to the Balkan Peninsula, Anatolia and the Caucasus

Abstract

The Balkan Peninsula harbours several Cardamine species endemic to this area with close relatives occurring in adjacent Anatolia and the Caucasus. They are perennials inhabiting wet habitats from lowlands up to the alpine belt. These species have been traditionally classified into three species complexes, namely the C. amara, C. pratensis, and C. raphanifolia (also referred to as C. tenera group) groups. Species relationships within and between the latter two groups, however, have been problematic, and species circumscription of some representatives from Anatolia and Caucasus have remained tentative. For instance, C. seidlitziana (Caucasus) has been sometimes considered as con- specific with the Balkan C. acris. The alpine C. uliginosa (Anatolia, Caucasus, reaching to Lebanon and Iran) is the most widespread, highly polymorphic species, previously also confused with lowland

C. penzesii.

In our study we apply the combination of next-generation sequencing method involving target en- richment capturing >1000 nuclear genes with genome skimming (Hyb-Seq), and multivariate mor- phometrics to resolve taxonomic and phylogenetic questions in these species complexes. Here we show that C. seidlitziana, although morphologically resembling C. acris, falls within the variation range of C. uliginosa. Cardamine penzesii appears phylogenetically closer to C. uliginosa than to oth- er members of the C. pratensis group, in congruence with its morphology. In summary, we conclude that the studied Cardamine species from the Balkan, Anatolia and Caucasus regions share their evolutionary history, and also demonstrate traces of past interspecific hybridization, in exceptional cases leading to allopolyploids.

Acknowledgements. This work is supported by the research grant from the Slovak Research and

Development Agency (APVV; grant APVV-17-0616).