Desert oases as genetic refugia of heritage crops: Persistence of forgotten fruits in the Mission orchards of Baja California, Mexico

Gary Paul Nabhan¹*, Jesus Garcia², Rafael Routson³, Kanin Routson⁴ and Micheline Cariño-Olvera⁵

¹Southwest Center, University of Arizona, Arizona, United States.

² Kino Fruit Trees Project, Arizona Desert-Sonora Museum, Arizona, United States.

³School of Geography and Development, University of Arizona, Arizona, United States.

⁴Arid Lands Resource Sciences, University of Arizona, Arizona, United States.

⁵Universidad Autónoma de Baja California Sur, Mexico.

*Corresponding author. E-mail: gpnabhan@email.arizona.edu. Tel: 928-225-0293.

Fax: 520-621-2484.

Accepted 11 January, 2010

     Abstract

The first introductions of agricultural crops to desert oases of Baja California, Mexico were initiated by Jesuit missionaries between 1697 and 1768 and historic records from these Jesuits provided a detailed benchmark by which temporal changes in agro-biodiversity can be measured. Longitudinal studies at the agricultural oases on the Baja California peninsula of Mexico can help determine whether such isolated “islands” of cultivation function as refugia or de facto reserves for in situ conservation of eighteen perennial species introduced by Jesuits. We compared survivorship of these historically introduced perennials at nine oases and determined that at least fifteen of the original eighteen Mission-era introductions of perennial species persist at these Baja California oases and one additional species persists on the peninsula outside of its original historic context. Despite this level of overall persistence, no species is cultivated in all nine oases. The archipelago of cultivated oases in Baja California should be considered as an aggregate worthy of conservation investments, rather than assuming that any single oasis is sufficient to maintain all historic varieties in the future. We use an analysis of the “forgotten fruits” of Baja California’s missions and ranchos to propose that the theory of island biogeography may be applicable to conservation planning for agro-biodiversity, as it has been for wild biodiversity nested in isolated habitats.

Key words: Agro-biodiversity; in situ conservation, desert oases, heritage foods, heirloom fruits, Mexico, island biogeography, genetic erosion, Baja California.