Molecular phylogenetic and genome-wide analyses of Artocarpus (Moraceae): Implications for the systematics, origins, human-mediated dispersal, and conservation of breadfruit

Artocarpus is the third largest genus in the Moraceae family and is native to Southeast Asia and Malesia. It includes several important cultivated species including breadfruit, a traditional starch crop in Oceania. However, no in-depth phylogeny exists for the genus and the origins of breadfruit remain unresolved. A phylogeny based on DNA sequence and morphological data from Artocarpus and four other genera (Hullettia, Parartocarpus, Prainea, and Treculia) in the same subtribe, reveals both the subtribe and the genus Artocarpus to be paraphyletic. The results are considered with regard to character evolution and are used to propose a new subgeneric treatment of the genus Artocarpus. The phylogeny is also used to determine the closest wild relatives of breadfruit, which are studied in greater detail with the genome-wide DNA fingerprinting technique amplified fragment length polymorphisms (AFLP). Two species, A. camansi and A. mariannensis, are shown to be involved in breadfruit origins. In Melanesia and Polynesia A. camansi is the primary progenitor of breadfruit, while in Micronesia, the majority of cultivars are the result of introgressive hybridization involving both species. Because breadfruit is primarily seedless, it had to be dispersed by humans throughout the Pacific Islands. This human-mediated dispersal is considered in light of human migration events in Oceania. AFLP fingerprints unique to each wild species were traced in breadfruit cultivars throughout the Pacific Islands and support a human-mediated dispersal of breadfruit eastward through Melanesia into Polynesia as well as a northerly migration from eastern Melanesia into Micronesia. The AFLP data is also used to assess the genetic diversity of Pacific breadfruit, particularly cultivars represented in the National Tropical Botanical Garden breadfruit collection, and to target additional species closely related to breadfruit for conservation.