Artocarpus altilis (breadfruit)

Nyree Conard Zerega
Director,  Plant Biology and Conservation Master's Program
Northwestern University & The Chicago Botanic Garden

2205 Tech Drive
Hogan 6-140A
Evanston, IL 60208

Phone: (847) 467-1266  
E-mail: n-zerega@northwestern.edu

Ph.D. 2003, New York University and The New York Botanical Garden
M.S. 1998, New York University
B.A. 1995, Truman State University

RESEARCH INTERESTS

My research integrates molecular, morphological, and phylogenetic tools with fieldwork to investigate the systematics, evolution, biogeography, and reproductive ecology of plants. I am also interested in the origins of cultivated plants. My work focuses primarily on members of the Moraceae (mulberry) family (~1100 species in 37 genera). The family displays an amazing array of diversity in inflorescence structures, pollination syndromes, breeding systems, floral characters, and growth forms. This diversity makes it an excellent group for addressing many intriguing evolutionary questions. Additionally, it includes several important food and fiber sources such as breadfruit, figs, and paper mulberry.  Some recent projects are briefly summarized below.


BREADFRUIT ORIGINS.  Breadfruit 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).

  click here for larger image

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 AFLPs and morphological characters to revise breadfruit taxonomy (Zerega et al. 2005). Three species and hybrids are recognized. Much of the plant material used in this study came from the world's largest and most comprehensive breadfruit germplasm collection located at the Breadfruit Institute at the National Tropical Botanical Garden (NTBG) in Hawaii.
breadfruit
Breadfruit, Artocarpus altilis

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, Noor, and Motley, in preparation).

jackfruit, Artocarpus heterophyllus


DORSTENIA SYSTEMATICS. With 105 species, Dorstenia is the second largest genus in the Moraceae. 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). Work is focused on Dorstenia phylogeny reconstruction to test sectional classification, study character evolution, and for biogeographcial studies. The evolutionary framework will also direct pollination studies in the family.
Dorstenia hildebrandtii

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, Clement, Datwyler, and Weiblen, in review). 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.
Ficus dammaropsis syconium
(photo by George Weiblen)

 

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, in press).  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.

Antiaropsis decipiens infructescence


PUBLICATIONS

Zerega, N.J.C., D. Ragone, and T.J. Motley. 2005. Breadfruit Origins, Diversity, and Human-faciliated Distribution. Pp. 213-238 in T.J. Motley, N.J.C. Zerega, and H.B. Cross [eds.], Darwin 's Harvest: New Approaches to the Origins, Evolution, and Conservation of Crops. Columbia University Press, New York , New York , USA .

Motley, T.J., N.J.C. Zerega , and H.B. Cross. 2005. Darwin 's Harvest: New Approaches to the Origins, Evolution, and Conservation of Crops. Columbia University Press, New York , New York , USA .

Zerega, N.J.C ., D. Ragone, and T.J. Motley. 2005. Species limits and a taxonomic treatment of breadfruit ( Artocarpus , Moraceae). Systematic Botany 30(3): 603-615.

Zerega, N.J.C ., W.L. Clement, S.L. Datwyler, and G.D. Weiblen. 2005. Biogeography and divergence times in the mulberry family based on chloroplast and nuclear DNA sequences . Molecular Phylogenetics and Evolution 37: 402-416.

Zerega, N.J.C. , Mound, L.A. , and G.D. Weiblen. 2004. Pollination in the New Guinea endemic Antiaropsis decipiens (Moraceae) is mediated by a new species of thrips, Thrips antiaropsidis (Thysanoptera: Thripidae). International Journal of Plant Sciences 165(6): 1017-1026.

Zerega, N.J.C ., D. Ragone, and T.J. Motley. 2004. Complex origins of breadfruit: Implications for human migrations in Oceania . American Journal of Botany 91(5): 760-766.

Motley T. J., L. Lück and N. J. C. Zerega . 2004. Genetic diversity and DNA fingerprinting of black cohosh ( Actaea racemosa ). Proceeding of the Global Summit on Medicinal Plants 1:112-118 .

Zerega, N.J.C. 2003. The Breadfruit Trail. Natural History 112(10): 46-51.

Zerega, N.J.C. , S. Mori, C. Lindqvist, Q. Zheng, and T.J. Motley. 2002. Using amplified fragment length polymorphisms (AFLP) to identify black cohosh ( Actaea racemosa ). Economic Botany 56(2): 154-164.

Bultman, T.L. and N.J. Conard . 1998. Effects of endophytic fungus, nutrient level, and plant damage on performance of Fall Armyworm (Lepidoptera: Noctuidae). Environmental Entomology 27(3): 631-635.

 Page last updated September 6, 2006