MEUDT, HEIDI* and BERYL SIMPSON. Section of Integrative Biology and the Plant Resources Center, The University of Texas at Austin, Austin, TX, 78712. - Austral Biogeography: The Evolution of Subalpine Ourisia (Scrophulariaceae s.l.) in a Phylogenetic Context.
We are investigating the biogeography and evolution of the austral,
subalpine genus Ourisia (Scrophulariaceae s.l.) using molecular data.
Species of Ourisia are found in the South American Andes (17 spp.),
alpine Tasmania (1 sp.), and the mountains of New Zealand (ca. 22
taxa). Sequences of three DNA markers, the nuclear Internal
Transcribed Spacer (ITS1, 5.8S, ITS2), chloroplast matK-3’trnK intron,
and chloroplast rps16 intron, have been obtained from 37 ingroup taxa
(or ca. 90% of the genus) and 15 outgroup genera. Phylogenies
reconstructed from separate and combined analyses of these data
indicate that Ourisia is composed of two well-supported clades
corresponding to differences in habit. One clade contains three
suffruticose southern Andean species, while the other clade contains
all the herbaceous species, including the remaining Andean species
plus all New Zealand and Tasmanian taxa. The New Zealand Ourisia form
a derived, poorly resolved, monophyletic group, perhaps suggestive of
a recent, rapid radiation in the mountains there. Ourisia integrifolia
from Tasmania appears to be sister to the New Zealand clade. These
results are most consistent with long-distance dispersal of Ourisia
from South America to Tasmania and subsequently New Zealand. These
data add to the growing body of evidence that dispersal, not
vicariance, may be responsible for the austral biogeographic patterns
of other plant groups.
Key words: Andes, Austral Biogeography, molecular phylogeny, New Zealand, Scrophulariaceae s.l., Tasmania