Reveal, Delwiche, and Hibbs The high Andes of South America support a unique flora of high endemism (restricted geographic range). However, compared with the lowland neotropical forest, the history and diversity of the high Andean paramo (or puna) vegetation have received relatively little attention from systematists. The biogeographic and evolutionary origin of the distinctive paramo flora is particularly interesting in view of the presumably recent geological origin (Plio-Pleistocene) of the high Andean habitats. Certain elements of this flora appear to have evolved in place from lowland ancestors, while other elements dispersed to the paramo from cool regions elsewhere, such as the Nearctic. The high Andean tree genus Polylepis (family Rosaceae, tribe Sanguisorbeae) is a major component of many paramo environments, and is thought to include 20-30 species in South America. The multiple layers of flaky bark and the small, hairy leaves are considered adaptations to harsh, cold climatic conditions in the Andean alpine and high-montane zones. In this project, graduate student Malin Hibbs, under the direction of Dr. James Reveal and Dr. Charles Delwiche at the University of Maryland, will investigate the evolutionary and biogeographic history of Polylepis and its close relatives in the tribe Sanguisorbeae using DNA sequence data from chloroplast and nuclear genes, in association with morphological studies on flowers and fruits. The inferred evolutionary relationships together with extant distribution patterns will be used to estimate a biogeographic history of the tribe, and in particular to assess the relative roles of elevational speciation (derivation of species from ancestors lower or higher in elevation) or lateral dispersal (derivation from stocks at similar elevations north or south along the Andean axis). Suveys of the distribution and status of the genus Polylepis are also of importance from a conservation standpoint because the plants are threatened by deforestation and introductions of foreign trees, usually members of the genera Eucalyptus and Pinus. In addition to the threat to Polylepis itself, many other species are dependent upon the habitat that Polylepis provides. Over a hundred species of birds have been recorded from Polylepis woodlands in South America, many of which are local endemics completely dependent upon this habitat. The taxonomic, phylogenetic, and natural-history results from this study will serve general biological and conservation goals.
