1492 and the loss of amazonian crop genetic resources. II. Crop biogeography at contact

Fifty seven percent of the 138 cultivated plant species present in Amazonia at contact probably originated in the Amazon Basin and another 27% origina ted in lowland northern South America. The relationship between probable in digenous human population density and resultant agricultural intensificatio n and crop diversity is used to propose the existence of a mosaic of crop g enetic resource concentrations in Amazonia at contact including two centers of diversity, four outlying minor centers, and five regions of diversity. This methodology is extrapolated to present a synthesis of South American c rop genetic biogeography at contact.