Ex situ conservation of crop wild relatives, which means protecting them outside of their natural habitats, is essential both to prevent the loss of CWR genetic diversity and to facilitate the use of their diversity in crop breeding. In situ conservation, in contrast, involves the maintenance and recovery of populations of crop wild relative species in their natural surroundings, and is necessary to ensure their continued evolution in the field, including the natural exchange of genes with each other and their cultivated cousins.
Crop wild relatives are held ex situ in national crop diversity collections, international genebanks such as those of the CGIAR, the Millennium Seed Bank, and the Svalbard Global Seed Vault. Examples of in situ conservation of CWR include the Sierra de Manantlán Biosphere Reserve in Jalisco, Mexico, which preserves the endemic maize relative Zea diploperennis, and the Erebuni Reserve in Armenia, which helps to conserve a number of wild wheat relatives and other wild cereal species.[i] In some instances, CWR are the primary goal of in situ conservation efforts, while in others, CWR are present in existing protected areas that were established for other purposes.
