Different speciation types meet in a Mediterranean genus: the biogeographic history of Cymbalaria (Plantaginaceae)

Cymbalaria is a Mediterranean genus including ten species and six subspecies growing on rocky habitats. A very fragmented distribution, the different ecologic preferences of partially sympatric species and the presence of different ploidy levels, suggest the role of allopatric, sympatric ecological and polyploid speciation in its evolution. The aims of this study are to verify the monophyly and to reconstruct the phylogenetic relationships of Cymbalaria, to infer its biogeographic history by estimating the lineage divergence dates and the ancestral areas of distribution, and to discuss the role of different types of speciation. To address these issues, we constructed a complete phylogeny of the genus with ITS, 3ETS, ndhF and rpl32-trnL sequences. A time-calibrated phylogeny and an ancestral-area estimation were obtained from the nrDNA data. The evidence supported the genus Cymbalaria as monophyletic. It originated ca. 5 Ma and three lineages segregated rapidly, one with the single extant taxa Cymbalaria microcalyx subsp. microcalyx and the other two corresponding to western and central-eastern species, respectively. The main diversification events occurred after the onset of the Mediterranean climate and during Pleistocene oscillations. Founder-event and sympatric speciation were supported by the biogeographic analyses, and chromosome data combined with our phylogeny supported at least two polyploidization events. We observed that the consequences of physical barriers were different amongst the different species.\n\nSupplementary MaterialElectronic Supplement (Figure S1, Table S1) are available in the Supplementary Data section of the online version of this article (http://www.ingentaconnect.com/content/iapt/tax).