In situ conservation of maize in Mexico: Genetic diversity and maize seed management in a traditional community

Results from a study of maize varieties and seed sources in a traditional community in Jalisco, Mexico, raise questions about the relationship between generic erosion and the introduction of varieties. The relevance of models for in situ conservation of crop genetic resources based on geographical isolation of a community is discussed The morphophenological diversity of local materials is shown to be enhanced by introductions of both improved cultivars and landraces from farmers in other communities. On the other hand, the geographical point of reference for defining ''local'' landrace is shown to be larger than the community itself: Farmers will classify seed obtained from other farmers in and outside the community as that of a local landrace if it resembles their own according to the phenotypic characteristics they use to distinguish varieties. Maize diversity in this community is then the result of a certain level of introduction of genetic material and not of geographical isolation.