Evolution and Diversification in the Sapindales
Miller, Allison .
Origin and evolution of Spondias purpurea (Anacardiaceae).
Domestication occurs as humans select and cultivate wild plants in agricultural habitats. In the Sapindales, numerous tree species are cultivated for their fruits, including citrus, cashew, lychee, mango, marula, pink peppercorn, pistachio, and rambutan, among others, but few studies have investigated the domestication process in Sapindalean taxa. This study documents the evolutionary history of one of the important tree crops of the Sapindales, the jocote tree, Spondias purpurea (Anacardiaceae), a native of Mesoamerica. DNA sequence data from the chloroplast (trnG-trnS) and nucleus (pepC IV) are used to delimit the S. purpurea lineage in Mesoamerica, and to identify regions within Mesoamerica where S. purpurea may be hybridizing with closely related species. The geographic origins of cultivated S. purpurea populations are identified using chloroplast sequence data and aflp data. The impact of human selection on the amount and structure of genetic variation in cultivated S. purpurea populations is quantified using aflp data. Changes in the ecological characteristics of the S. purpurea distribution are assessed using ecological niche modeling techniques. Results indicate that S. purpurea is a distinct lineage in Mesoamerica but is hybridizing with S. mombin and S. radlkoferi in restricted portions of its range (northwestern Costa Rica and southwestern Nicaragua). Chloroplast sequence data and aflp data provide evidence for at least two independent origins of cultivated populations from their wild progenitors, one in western Central Mexico and one in Central America. The domestication process in S. purpurea resulted in decreased levels of genetic variation, and increased structure in genetic variation, in cultivated S. purpurea populations relative to wild S. purpurea populations. Finally, human selection during domestication has led to cultivated S. purpurea populations that occupy a wider range of habitats than their wild ancestors.
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1 - Saint Louis University, Biology, 3507 Laclede Avenue, St. Louis, MO, 63103, USA
crop wild relatives.
Presentation Type: Symposium or Colloquium Presentation
Location: Boulevard B/Hilton
Date: Tuesday, July 10th, 2007
Time: 11:15 AM