The Peruvian and Atacama coastal deserts of South America (8-28 degrees S latitude) are the planet's driest and most inhospitable landscapes, often compared to those found on Mars. Although these deserts are largely devoid of plants, there are "oases" of vegetation made possible by local seasonal accumulation of fog precipitation. Biologists have studied speciation in oceanic islands, but, less studied are "virtual" islands that exist within continental ecosystems and are isolated by intervening habitats. In the coastal deserts, such communities are called "lomas formations" and occur as discrete islands of vegetation, separated by varying distances of hyper-arid habitat. The lomas formations represent a virtual archipelago, largely unstudied. They offer the perfect laboratory for examining evolutionary patterns and testing biogeographic hypotheses. With 85 species, the plant genus Nolana (Solanaceae or Potato Family) is one of the most frequently encountered members of the Atacama and Peruvian desert flora, with at least one species occurring on every lomas island. Nolana species exhibit extensive variation in growth habit, vegetative and floral morphology, and ecological preferences, making them an ideal subject for investigating evolutionary models, taxonomic relationships, and distribution patterns. Dr. Michael Dillon and his colleague Dr. Jun Wen at the Field Museum of Natural History will conduct comprehensive field studies in coastal Chile and Peru to collect at least 75 species of Nolana. Three nuclear genes (GBSSI, nitrate reductase (NIA) introns, ribosomal 5S) and two chloroplast genes (trnC-trnD region, ndhF ) will be DNA-sequenced from all these samples to measure mutational differences and to examine the evolution and biogeographic history of Nolana. Molecular and morphological results will be used to test hypotheses of broad-scale distribution patterns in the coastal deserts. Further, the evolutionary history of Nolana holds clues to the age and origin of the coastal deserts and their reactions to short-term events (ENSO or El Nino phenomena) and longer-term events (glacial cycles and sea-level changes). Additional products from the research will include a comprehensive taxonomic monograph of Nolana and extensive development of website accessible information. Islands and their biotas have long interested students of evolution and biogeography. The results of this project will provide important insights into the genetic diversity of Nolana and will establish strategies for the conservation of threatened and endangered species within coastal desert environments. The project will provide training for a graduate student and a post-doctoral researcher in both field and laboratory methodologies in plant systematics and biogeography. The research will be developed in close collaboration with scientists and students in Chile and Peru. Our discoveries will be of interest not only to plant scientists and ecologists, but also to climatologists, ecophysiologists and geoarcheologists.
