Molecular phylogeny of Edraianthus (Grassy Bells; Campanulaceae) based on non-coding plastid DNA sequences

Abstract

The Balkan Peninsula is known as an ice-age refugium and an area with high rates of speciation and diversification. Only a few genera have their centers of distribution in the Balkans and the endemic genus Edraianthus is one of its most prominent groups. As such, Edraianthus is an excellent model not only for studying speciation processes and genetic diversity but also for testing hypotheses regarding biogeography, identification and characterization of refugia, as well as post-glacial colonization and migration dynamics in SE Europe. The genus comprises 10 to 28 species and was traditionally divided into three sections: E. sect. Edraianthus, E. sect. Uniflori, and E. sect. Spathulati. We present here the first phylogenetic study of Edraianthus based on multiple plastid DNA sequences (trnL-F region and rbcL-atpB spacer) derived from a wide taxonomic sampling and geographic range. While the sister-group to Edraianthus could not be ascertained, the results strongly support its monophyly as currently circumscribed. The phylogentic relationships among Edraianthus and its closely related genera Halacsyella, Petkovia, Muehlbergella, and Protoedraianthus are discussed and their respective taxonomical standings are reevaluated based on molecular evidence. Our study identified several distinct monophyletic groups within Edraianthus, some of which correspond closely to previously established taxonomic treatments and some of which are first identified here. Morphologic, taxonomic, and biogeographic implications of these relationships are also discussed.