Hahn and Noblick Dr. William Hahn of Columbia University and Dr. Larry Noblick of the Montgomery Botanical Center are combining their molecular and morphological expertise to study the systematics and evolution of the coconut, Cocos nucifera, and its taxonomic relatives. The coconut is one of the three most economically important species of palms, yet its origins and relationships are poorly understood. The palm tribe Cocoeae consists of 22 genera (including the coconut) with two genera in Madagascar, one genus in South Africa, the coconut in Southeast Asia and the Pacific, and the remaining 18 genera in the New World. Available taxonomies for the tribe are in need of critical reevaluation as several different taxonomies have been proposed over the past few decades. An estimate of evolutionary relationships is needed to resolve these taxonomic debates as well as controversy over the geographic origin of the coconut. The species appears to be native to Southeast Asia and the South Pacific, but all of its close relatives are found in Africa, Madagascar, or the New World. Because of its remarkable ability to disperse by floating, both natural and human-mediated dispersal have been suggested to explain its origins and current distribution. Two primary geographic scenarios have been proposed: from Madagascar/Africa across the Indian Ocean or from the Americas across the Pacific Ocean. An explicit examination of the coconut's relationships to other palms is necessary to choose between these competing biogeographic hypotheses. Dr. Hahn and Dr. Noblicks's research uses modern molecular and morphological phylogenetic methods to reconstruct the evolutionary history of the coconut and related species and to develop a molecular clock framework for the evaluation of rates of diversification. Morphological and molecular data will be accumulated to estimate evolutionary relationships among the 22 genera that form tribe Cocoeae, with anticipated improvements to genus-level circumscription and classification. Molecular clocks (based on multiple nuclear and plastid genes) will be used to date divergence events among the taxa in this tribe and to estimate the time of origin for the coconut. Based on these results, tests of alternative taxonomic and biogeographic hypotheses can be conducted, leading to a better understanding of the evolutionary process in an economically important crop species. Both graduate and undergraduate students will be supported in this project and will be instructed in field, botanical garden, herbarium, computer, and molecular evolutionary techniques. Results of these studies will also be presented in the public education programs of the Montgomery Botanical Center in Miami, Florida.
