Phylogenetic relationships of the Siberian iris species inferred from noncoding chloroplast DNA sequences

A study of phylogenetic relationships of Iris species has been complicated because of extreme morphoecological diversity, wide distribution of the genus, multiple hybridizations, and convergent evolution processes in the genus. In order to get an insight into the evolutionary history of Iris and to clarify some contradictions of contemporary classifications, we performed a molecular analysis of the phylogenetic relationships of a heterogeneous group of Iris species occurring in Siberia and covering major taxonomic groups of the genus Iris. According to contemporary classifications, these species belong to the subgenera Limniris (Tausch) Spach, Xyridion (Tausch) Spach, Iris, and Pardanthopsis (Hance) Baker. However, the position of Pardanthopsis within the genus Iris and the position of Xyridion as a distinct subgenus or a part of Limniris are disputable. Based on an analysis of 56 RAPD markers in 12 Siberian Iris species and comparative analysis of trnL intron and trnL-trnF intergenic spacer noncoding chloroplast DNA sequences in all 22 Siberian Iris species, we reconstructed the phylogenetic relationships of Siberian Iris species. In general, the species grouping coincides with contemporary classifications. According to our results, Pardanthopsis dichotoma forms a separate branch on the phylogenetic trees based on sequences of chloroplast DNA and RAPD analysis, which supports its position as a distinct genus. All of the Siberian Iris species are clustered into four phylogenetic groups. Our results indicate that the phylogeny and taxonomic structure of the genus Iris may need reconsideration.