WANNTORP, LIVIA. Department of Botany, Stockholm University, SE-106 91 Stockholm, Sweden. - Phylogeny of Gunnera.
Gunnerais a genus of angiosperms with 30-40 species occurring
in America, from Southern Patagonia to Mexico, in New Zealand,
Tasmania, the Malayan Archipelago, Hawaii, from South Africa to
Ethiopia and on Madagascar. Many studies have recently been conducted
in order to identify the systematic position of Gunnera. In
contrast, the phylogeny within Gunnerahas never been studied
before. Consequently, no cladistic studies intended to explain the
biogeographic antarctic pattern of Gunnerahave been presented
so far. The phylogeny of Gunnerais investigated here for the
first time by using three different gene regions, rbcL and the rps16
intron of the chloroplast genome, and the nuclear ribosomal
transcribed internal spacer (ITS) region. Analyses based on single
gene regions, as well as the combined analysis of the three gene
regions, all confirmed the same general phylogenetic pattern: the rare
G. herterifrom Uruguay, which is also the only annual in the
genus, is sister to all other species. Furthermore, the African G.
perpensais sister to two well-supported monophyletic clades, one
including all the South American and the Hawaiian species, and the
other comprising all the species from New Zealand, Tasmania and the
Malayan area. The phylogeny of Gunnerais discussed and in the
light of the new results, the evolution of some morphological
characters, as well as biogeographical patterns of Gunneraare
addressed.
Key words: biogeography, Gunnera, ITS, phylogeny, rbcL, rps16 intron