(centre of diversity) An area that shows considerable genetic diversity of certain crop plants and their relatives. Some gene centres, the primary centres, are believed to correspond to the region where a particular crop originated. For example, numerous forms of wheat exist in the Middle East and, since many of the wild relatives of wheat are also found in this area, it is believed the crop was first domesticated there. Other centres, the secondary centres, do not contain wild relatives and are believed simply to be areas where the crops have been cultivated for a considerable period. Ethiopia is an example of a secondary centre. Gene centres are typically found in mountainous regions. This may be because human communities are more isolated and climatic conditions more variable in such areas - both conditions that would lead to more rapid divergence of crop populations. The recognition of gene centres is important in conservation and plant breeding work as such areas are important reservoirs of natural genetic variability. See also genetic erosion. |
