9527866 Ayers Phylogenetic studies of plants of the Andean alpine tundra provide a unique opportunity to investigate evolutionary processes in tropical, high-elevation environments. Dr. Tina Ayers of Northern Arizona University is studying the genus Lysipomia, a medium-sized group of ca. 28 species of small "cushion" plants restricted to tundra-like communities in Andean South America. The greatest species diversity in Lysipomia is found in Ecuador and Peru on both sides of a major geologic break in the northern Andes known as the Piura Divide or the Huancabamba Depression. The apparent absence of widespread species and the presence of a large number of narrow ranging endemic species adjacent to the Depression argues for the idea that this barrier and associated climatic changes have played an important evolutionary role in Lysipomia phylogeny. The primary focus of the study is to construct a phylogeny of the species of Lysipomia using information from morphology, anatomy, chromosomes, and DNA, and based upon herbarium material and recent field collections. Because morphological features may show convergence in these harsh environments, independent data sets generated from both chloroplast (restriction enzyme mapping) and nuclear (ribosomal ITS sequences) DNA will be emphasized. Other groups of Campanulaceae show major rearrangements in gene order on the chloroplast chromosome, and special efforts will be made to map such rearrangements, if encountered, in Lysipomia. A species-level phylogeny will allow tests of modes of speciation and adaptive radiation in Andean alpine habitats, and will help reconstruct the historical biogeography of high-elevation tropical communities.
