JACKFRUIT DIVERSITY AND ORIGINS. The place of origin and wild ancestor of jackfruit (Artocarpus heterophyllus, Moraceae) is unknown. It has been cultivated for millennia and was referred to as early as 300 B.C. by Theophrastus. It is now so widely cultivated that the region in which it is indigenous and where its greatest diversity may lie is unclear. Today it can be found in cultivation at low elevations from the Indian subcontinent through Bangladesh, Myanmar, into Southern China, Laos, Vietnam, Cambodia, Thailand, Malaya, Indonesia and Oceania. It is also commonly cultivated in the Philippines, and has been introduced throughout Africa and the Neotropics. While the western Ghats of India is commonly cited as its location of origin, there is very little evidence to support this and little work has been conducted on understanding jackfruit diversity. We are developing microsatellite markers for jackfruit to investigate its genetic diversity and origins and are also conducting ethnobotanical studies of jackfruit in Bangladesh
BREADFRUIT ORIGINS. Breadfruit (Artocarpus altilis, Moraceae) is a traditional starch crop in Oceania where it has been cultivated and improved upon by human selection for millennia and today hundreds of seedless as well as seeded cultivars exist. The entire tree can be utilized by humans, but it is primarily grown for its fruit. I have used AFLPs (Amplified Fragment Length Polymorphisms) to investigate the origins of breadfruit and its human-mediated dispersal through Pacific Island groups (Zerega 2003, Zerega et al. 2004). I am currently developing microsatellite markers for breadfruit.
BREADFRUIT SYSTEMATICS. The taxonomy of breadfruit has long been controversial with variable numbers of species being recognized and possible hybridization among them. I have used DNA fingerprinting and morphological characters to revise breadfruit taxonomy (Zerega et al. 2005). Three species and hybrids are recognized. Thee plant material used in this study came from fieldwork in Papua New Guinea, Micronesia, and the world's largest and most comprehensive breadfruit germplasm collection located at the Breadfruit Institute at the National Tropical Botanical Garden (NTBG) in Hawaii.
ARTOCARPUS PHYLOGENY. Artocarpus is the third largest genus in the Moraceae family and comprises approximately 60 species native to Southeast Asia and Malesia. Members of the genus are all latex producing, monoecious trees (rarely shrubs) with syncarpous fruits that can attain tremendous sizes (i.e. jackfruit, A. heterophyllus and chempedak, A. integer). While only the jackfruit and breadfruit, A. altilis, are commonly cultivated throughout the tropics, several other species are cultivated on a more regional scale in Southeast Asia for their timber, fruit, or seeds. Using nuclear and chloroplast DNA sequence data and morphological characters, an Artocarpus phylogeny has been reconstructed to study the evolution of inflorescence characters, address taxonomic issues, and identify wild relatives of the cultivated species in the genus (Zerega et al. 2010).
DORSTENIA SYSTEMATICS AND POLLINATION. With 105 species, Dorstenia is the second largest genus in the Moraceae family. Despite its close relationship with figs, virtually nothing is known about its reproductive ecology, and evolutionary relationships within the genus are not well understood. The genus is predominantly herbaceous (a unique condition in the family), and is evenly distributed between the Neotropics and Afrotropics (with one species reaching into Asia).A MS student, Tracy Misiewicz, focused on Dorstenia phylogeny reconstruction to test its monophyly, sectional classification, study character evolution, and understand Dorstenia biogeography. She has also conducted preliminary pollination studies in the family.
MORACEAE PHYLOGENY. Recent work has focused on biogeographical patterns and evolutionary rates of divergence in the Moraceae to understand when and where the family diversified (Zerega et al. 2005). Of particular interest are the temporal and geographic origins of the genus Ficus (figs) because of its highly specialized obligate mutualism with pollinating fig wasps. Figs and fig wasps are often considered to be a model for the study of coevolution and the implication is that figs diverged in parallel with their pollinators because the reproductive interdependence of these obligate mutualists requires that the lineages be temporally and geographically congruent. Although this supposition is commonly applied to host-specific ecological interactions, few studies have actually tested this hypothesis by considering independent divergence dates for interacting lineages. Estimation of divergence dates for Moraceae will enable the comparison of scenarios for the origin of fig pollination based on dates from both figs and fig wasps.
POLLINATION IN THE SISTER TRIBE TO FIGS. Although the obligate pollination mutualism between figs and fig wasps is well studied, very little is known about pollination in the rest of the Moraceae family. In order to better understand Moraceae pollination and the origins of the fig pollination syndrome, a member of the sister tribe (Castilleae) to figs has been investigated. Antiaropsis decipiens, a dioecious New Guinea endemic, is an early diverging lineage in the Castilleae. Based on phenological measurements, insect trapping, and pollinator exclusion experiments, a new species, Thrips antiaropsidis (Thysanoptera, Thripidae), has been recorded feeding on Antiaropsis pollen, breeding in the staminate inflorescences, and pollinating the carpellate inflorescences (Zerega, Mound, and Weiblen, 2004). It appears that thrips are lured from staminate to carpellate inflorescences by deceit. These findings combined with evidence of thrips pollination in neotropical Castilleae suggest that thrips pollination is common if not ubiquitous in the sister group to figs and entomophily coupled with breeding in inflorescences preceded the origin of the fig pollination mutualism. I am interested in pursuing additional pollination studies in the Moraceae family, particularly in the genus Artocarpus and closely related genera.
