Phylogenetic relationships and genetic diversity among members of the Festuca-Lolium complex (Poaceae) based on ITS sequence data

There have been few DNA sequence-based studies of phylogenetic relationship s within the Festuca-Lolium complex. Here we infer the phylogeny of 31 Fest uca-Lolium taxa with a dataset of 116 ITS sequences. The results are consis tent with previous studies that resolved two major Festuca clades: one clad e of fine fescues and another clade that contains Lolium and associated Fes tuca species. This study is unique in suggesting a third, basal Festuca cla de, but support for the basal position of this group is low. Extensive samp ling permitted investigation of the effects of lineage sorting and reticula te events on the evolution of the complex. Roughly half of the taxa show ev idence of lineage sorting or reticulation, and the monophyly of Lolium has likely been obscured by reticulate events. Overall, polyploid species harbo r higher levels of ITS sequence diversity than diploids; ITS sequence varia nts may provide clues to the identity of allopolyploid parents.