Phylogeography of the Moonwort Fern Botrychium Lunaria (ophioglossaceae) Based on Chloroplast DNA in the Central-European Mountain System

Botrychium s.s. is a cosmopolitan fern genus comprising about 35 currently recognized species. Despite unexpected high genetic diversity recently highlighted within Botrychium lunaria in the circumboreal region, few studies have included representative samples from Central Europe. Therefore, the aim of this work was to study the phylogeography of B. lunaria in the Central-European Mountain System and to compare it with that of flowering plants. Two noncoding chloroplast regions (psbA-trnH and trnL-F) were sequenced (918 bp) from 87 individuals from 34 populations in the major European mountain chains (Sierra Nevada, Pyrenees, Massif Central, Jura, Vosges, Black Forest, Alps, Apennines, and Carpathians). Among the 24 haplotypes found in the B. lunaria aggregate in Europe, bayesian phylogeny and median-joining network support four main clades (LUN1, LUN2, LUN3, and TUN). NST and GST comparison as well as homogeneous groups indicated by SAMOVA indicate a clear phylogeographical pattern. However, unlinked to geographical distance, genetic diversity is greatest in the Prealps and highlights three main barriers to gene flow: S–N of Central Alps (Aosta-Lepontic Alps), and two separating E–W Alps (Lago di Como-Rhaetian Alps and Dolomites-Noric-Julian Alps). Our results indicate that alpine populations of the B. lunaria aggregate survived the Quaternary glaciations in situ in two main refugia, in the southern and eastern periphery of the Alps. Not only areas with higher values of genetic diversity, but also refugia and sites of geographical boundaries to gene flow, appear similar in both ferns and flowering plants.