On the way to elucidating the complex evolutionary history and cryptic diversity of the Balkan-Anatolian Cardamine (Brassicaceae) species complex

Adam Kantor ¹, Marek Šlenker ¹, Dušan Senko ¹, Lenka Mártonfiová ², Gabriela Šrámková ³, Veronika Cetlová ¹, Ali A. Dönmez ⁴, Sırrı Yüzbaşıoğlu ⁵, Judita Zozomová-Lihová ¹

Plant Science and Biodiversity Centre, Slovak Academy of Sciences, Bratislava, Slovak Republic ¹, Botanical Garden of P. J. Šafárik University in Košice, Košice, Slovak Republic ², Department of Botany, Faculty of Science, Charles University, Prague, Czech Republic ³, Department of Biology, Faculty of Science, Hacettepe University, Beytepe-Ankara, Türkiye ⁴, Department of Botany, Faculty of Science, İstanbul University, Istanbul, Türkiye ⁵

Deciphering patterns of diversification at the lower taxonomic levels is crucial for understanding evolution of biodiversity of a specific region in a broader context. For example, we know little about the significance of interplay of specific mechanisms and factors shaping evolution of most individual species. Resolving evolutionary histories may be especially important but challenging in regions such as the Balkan Peninsula, which represents center of species and genetic diversity with a high representation of endemics. Survival and diversification of species in this area was facilitated by several specifics of this area, including its topographical heterogeneity, diversity of habitats and favorable conditions during the Pleistocene climatic oscillations. In the recently published study, we focused on unravelling the diversity of mountain hygrophytes from the species complex Cardamine acris s.l., which in its original understanding included the Balkan species C. acris (with three recognized subspecies) and the species C. anatolica, endemic to northwestern Anatolia. We used a series of phylogenetic and phylogeographic analyses based on data obtained by restriction-site associated DNA sequencing (RADseq) and target enrichment (Hyb-Seq), supplemented by habitat suitability modelling. This combination of methods provided us with surprising results that had not been discovered in multiple previous studies which were based on far less robust sequence data. Instead of four originally recognized entities, we were able to distinguish six within the studied complex, while the Asian clade of C. anatolica turned out to be nested within the other Balkan lineages. The Balkan lineages most likely arose by vicariance, being allopatrically distributed, although we found also direct evidence of gene flow between two of them. Habitat suitability dynamics modelling shown that the ecological confinement of these plants to mountains and humid habitats played a fundamental role in expansion and diversification of the species complex. Another novel finding concerned the cytotype diversity of the complex: all taxa were previously thought to be exclusively diploid, however, we discovered populations of four different ploidy levels in the Balkans, originating both via intra- and inter-lineage polyploidization. Our results underline already known complexity of plant evolution in the Balkans, which has been shaped by interlaced combination of multiple processes. In the current study in progress, we aim to further analyze this recently discovered cryptic diversity and investigate if and how it links to phenotype and DNA content of the members of the species complex. We use multivariate morphometric analyses and genome size measurements acquired by flow cytometry to evaluate differentiation among the six entities. Outcomes of these analyses will be used to provide reevaluated taxonomic concept for the challenging species complex of C. acris s.l. This study is supported by the Slovak Research and Development Agency (Grant no. APVV-021-0044).

Main author career stage: Postdoc / Fellow

Contribution type: Poster

First choice session: 1. Systematics, phylogenetics, biogeography and evolution

Second choice session: 5. Genetics, genomics, and bioinformatics