Evolution of Domestication

The study of plant domestication is one of the most interesting fields of plant evolutionary biology. We take a multi-disciplinary, collaborative approach to understanding the genetic, phenotypic, ecological, and social consequences of plant evolution in a tropical semi-domesticate.

CAIMITO: THE ORIGINS AND HISTORY OF A TROPICAL SEMI-DOMESTICATE

The caimito or star apple tree, Chrysophyllum cainito L. (Sapotaceae), is prized for its golden foliage and large, edible fruits. The origin of caimito is debated. Various authors have argued that it is native only to the Greater Antilles and was planted across Central and South America only after the Spanish Conquest, others claim it originated in Mexico, while others believe that it is a native to Central America. In Panama, it has been promoted as a native reforestation species. With collaborators Jennifer Petersen and Dan Potter of UC Davis, we tested hypotheses of the origin of this species and its center of domestication using phylogeographic approaches.

Our results suggest that C. cainito evolved and was domesticated in southern Mesoamerica or northern South America, not in Mexico or the Antilles. Panama contains a large proportion of the genetic diversity of this species and should be included in germplasm collections.

Jennifer Petersen

LIFE HISTORY TRADEOFFS AND HUMAN SELECTION VS. NATURAL SELECTION

Isis López

Harold Henry

A fundamental assumption of ethnobotany and the study of plant domestication is that natural selection in the wild necessarily acts in opposition to human selection. That is, that domesticated genotypes are less fit in natural environments than their wild progenitors. We are testing this hypothesis in caimito in Panama, where both natural selection and anthropogenic selection are currently at work. Our studies focus on 1) quantifying variation in fruit and seed traits, 2) understanding how these traits are influenced by domestication, and 3) understanding how these traits affect survival and success in the wild.

We have found that cultivated genotypes of caimito show a domestication syndrome of larger and sweeter fruits. The seeds from cultivated trees also germinate faster, have higher moisture content, and are more sensitive to desiccation. We are investigating the performance of wild-type vs. cultivated genotypes in the ancestral habitat, the tropical forest understory.

For more details, see:

Parker, I. M., López, I., Petersen, J. J., Anaya, N., Cubilla-Rios, L., & Potter, D. 2010. Domestication syndrome in Caimito (Chrysophyllum cainito L.): fruit and seed characteristics. Economic botany, 64(2), 161-175.

Petersen, J. J., Parker, I. M., & Potter, D. 2012. Origins and close relatives of a semi‐domesticated neotropical fruit tree: Chrysophyllum cainito (Sapotaceae). American Journal of Botany, 99(3), 585-604.

I do my research in Panama with the support of the Smithsonian Tropical Research Institute, where I am a Research Associate.

Read a STRI article about my work on caimito here. An essay on this work was written by Kate Galloway.

CONSERVING THE DIVERSITY OF TROPICAL FRUITS

Prof. Josué Ortiz, Lic. Francisco Abre and collaborators at Ciudad del Arbol

We collaborate with the University of Panama Extension and with Panamanian NGO/community organizers at “Proyecto Ciudad Del Arbol,” a reforestation site where we have established a common garden plantation of over 100 C. caimito genotypes from throughout Panama.

In addition to providing a common garden where we can study genetic variation in a common environment, our caimito plantation represents an important repository for genetic diversity for this species. The globalization of food production and distribution has had a negative impact on local knowledge and utilization of local plant products. We hope to contribute to reversing the loss of this species from Panama’s cultural and culinary heritage.

You can find publications from these projects and more at Ingrid's Google Scholar page.

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