Dissertation Research: Artocarpus Phylogenetics and Conservation, Taxonomy and Biogeography of Breadfruit (Artocarpus altilis)

New York Botanical Garden, Bronx NY

Investigators

Abstract

0073161 Motley and Conard The genus Artocarpus is a member of the fig and mulberry family (Moraceae). It consists of approximately 50 tree species all native to the tropics of Southeast Asia and the Pacific. Many of the species are cultivated on a local level for their timber, fruit, or seeds. Two species, breadfruit, A. altilis and jackfruit, A. heterophyllus, are important crops throughout the tropics. Despite the economic and subsistence significance of this group of plants, the evolutionary relationships among them remain unclear. Graduate student Nyree Conard, under the direction of Dr. Timothy Motley, is investigating these relationships, including morphological features as well as DNA sequences from all of the species, to create a phylogeny or "family tree" of the genus. The phylogeny will be useful for identifying close relatives of the cultivated species in the genus and for setting an evolutionary framework for more detailed species level studies such as conservation and germplasm work on breadfruit. Breadfruit is a traditional staple crop in the Pacific Islands where it has been cultivated and improved upon by human selection for millennia so that today hundreds of seedless and seeded varieties exist. Although the entire tree has uses, it is primarily harvested for either its starchy fruit or proteinaceous seeds. In the late 16th century European explorers began travelling to the Pacific Islands and wrote accounts of breadfruit. At this point in time, it was already being widely cultivated throughout Oceania (Melanesia, Micronesia, Polynesia) and the Europeans soon realized how useful the tree was and began distributing it to colonies throughout the tropics. Although its native region is known to be somewhere in Oceania, its precise center of origin and its subsequent human-facilitated dispersal route through the Pacific is unclear. Additionally, the taxonomy of breadfruit is controversial with one to three different species of breadfruit being recognized and possible hybrids existing. By using DNA fingerprinting techniques, relationships among varieties from different Pacific Island groups will be assessed to address the issues of origin, human-facilitated dispersal routes, and taxonomy. In addition to providing insight into human migrations in the Pacific, the fingerprinting data will also be used to help manage living breadfruit germplasm collections so that their genetic diversity can be most effectively utilized and conserved.