Molecular study of the Cardamine maritima group (Brassicaceae) from the Balkan and Apennine Peninsulas based on amplified fragment length polymorphism

Abstract

The amphi-Adriatic region, and especially the Western Balkan Peninsula, belongs to the most important biodiversity hotspots in the temperate region. Nevertheless, detailed phylogeographic and molecular systematic studies in the Western Balkan are rare due to sporadic sampling in regions, where access has been, until recently, restricted by war. The Cardamine maritima group, which is the focus of this study, comprises not only the currently recognised species C. maritima and C. monteluccii, but also other taxa, which have been rendered to synonymy by most of the national floras and checklists. Molecular data acquired by the amplified fragment length polymorphism method showed a clear pattern within the group. Italian populations of C. monteluccii are well separated from Balkan taxa. In a step forward from previous taxonomic confusion surrounding Balkan populations, the present study confirms that five allopatric units—each with a clearly delimited and a rather restricted distribution range—can be easily recognised here. They correspond to C. fialae, C. serbica, C. rupestris, and two genetically distant and allopatric units within C. maritima. While individual taxa gained high bootstrap support in the neighbour-joining tree, there is low support for the internal nodes and it is hard to infer any relationships among taxa based on this information. The majority of Balkan populations of the C. maritima group exhibit features of genetic variability that enable us to hypothesise that these populations are relic ones.