Evolutionary history of the chili pepper Capsicum baccatum L. (Solanaceae): domestication in South America and natural diversification in the Seasonally Dry Tropical Forests

Plant domestication genetics has been of interest not only for evolutionary biologists but also for anthropologists and breeders, because of its past and present role in human cultural evolution. Capsicum baccatum, which grows in the Seasonally Dry Tropical Forests of South America (SDTF), was domesticated by native peoples and used as a spice. The centre of domestication has been discussed, and vast territories of Peru and Bolivia have been proposed. The aims of this research were to elucidate the geographical origin of cultivated C. baccatum and to infer geological and climate events that have influenced the distribution of its genetic variability. Samples were collected from 25 localities across the entire range of wild C. baccatum and analysed using DNA sequences and phylogeographical approaches; they were then compared with 20 samples of cultivated forms obtained from different South American markets. We found a main centre of C. baccatum domestication spanning Bolivian Amazonia and the inter-Andean valleys. We also inferred an ancient cultivation site between Bolivia and Argentina. Finally, we found two lineages of wild populations distributed in nuclei of SDTFs which have been fragmented during glacial periods, when aridity increased and expansion of Chaco vegetation fragmented the region.