PHYLOGENY AND BIOGEOGRAPHY OF THE GENUS FERULA (FERULINAE, APIACEAE)

Phylogenetic relationships within Apiaceae tribe Scandiceae subtribe Ferulinae were investigated using sequence data from the chloroplast DNA and nuclear ribosomal DNA internal transcribed spacer (ITS) regions. One hundred and seventy-six accessions were examined, representing the genera of the subtribe (Ferula, Dorema, Leutea) and outgroup taxa. The cpDNA markers included three non-coding loci: rpoB-trnC intergenic spacer, rps16 intron and rpoC1 intron. These loci were analyzed separately and combined to assess their relative utility for resolving relationships. Partition homogeneity tests yielded trees that demonstrated the incongruency between cpDNA and nrDNA regions. Among the loci examined, rps16 intron showed less variability relative to its size than the other used cpDNA markers. Phylogenies derived from maximum parsimony and Bayesian analyses of combined cpDNA and nrDNA sequences for 156 accessions (representing 114 species of Ferula, 6 species of Dorema, 9 species of Leutea and 10 outgroup taxa) were resolved to some extent. Based on these analyses, Dorema is nested within Ferula and should be therefore subsumed within the latter. In contrast, Leutea appears to be in a sister position to Ferula and should be retained as a separate genus. Biogeographical inferences were obtained by applying statistical dispersal- vicariance analysis (S-DIVA) and Bayesian binary MCMC (BBM) analysis implemented in RASP. These analyses revealed that subtribe Ferulinae has originated in the Armeno-Iranian Province and diversified in central Asia, floristically encompassing the central and eastern part of the Irano-Turanian Floristic Region, where the representatives of nearly all major groups occur. The notable exceptions are two groups that are mostly distributed in the Mediterranean region and in China. Since the species boundaries in Ferula are not clear, one may also suspect that the high number of species, particularly of the central Asiatic endemics, may have resulted from taxonomic splitting rather than rapid radiation of the genus in this region.