New insights into the phylogeny and biogeography of the Gerbera- Complex (Asteraceae: Mutisieae)

The inter-generic relationships within the subfamily Mutisioideae (Asteraceae/Compositae) are historically uncertain. Most of the genera that once were recognized within the Mutisioideae s.l. are now segregated into a number of different tribes and subfamilies. In particular, the generic delimitations of the Gerbera-Complex, an informal group inside the tribe Mutisieae s.str., have been widely discussed. The species are generally herbs with monocephalous scapes and are grouped in eight genera: Amblysperma, Chaptalia, Gerbera, Leibnitzia, Lulia, Trichocline, Perdicium and Uechtritzia. The characters that delimit the inter-generic boundaries are still under discussion and the complex has never been the subject of a species-level molecular investigation to test the monophyly of the genera. This study presents a molecular phylogeny of the Gerbera-Complex based on both nuclear (ITS) and plastid (trnL-trnF, trnL-rpl32) markers, and provides the relative ages of this group and a reconstructed biogeographic history. The phylogenetic analysis showed two clades inside the Gerbera-Complex. Clade A contains only South American endemic genera, in which Lulia is sister to Brachyclados+Trichocline. Clade B mainly contains groups of taxa that colonized other continents including areas in the northern temperate latitudes. Clade B is further divided into two clades where Gerbera is shown to be non-monophyletic because the African Gerbera clade is sister to Amblysperma and the Asian Gerbera clade includes Uechtritzia. The biogeographic and molecular dating show a South American origin for the early-divergent nodes of the subfamily with a node age of 47.52–49.67 Ma in the Eocene. The Gerbera-Complex is likely to have originated in the Andes in the late Oligocene (mean node age of around 25.74 Ma) followed by long-distance dispersal events to North America and Asia, and separate dispersal events to Africa and Australia. This is the first phylogenetic analysis to show the systematic positions of Amblysperma, Lulia and Uechtritzia.