ABSTRACT
Changes in wheat diversity in Australia between 1965 and 1997 are examined at three levels: national, state, and shires within the state of New South Wales (NSW). Two measures of apparent spatial diversity, richness and evenness of named varieties, as well as the latent spatial diversity based on variety pedigrees, are assessed at each level. At the national level, richness and evenness measures indicate that diversity increased during the period. At the state level, three states had relatively steady diversity, and two had increasing levels. At the shire level, apparent diversity was considerably lower than at the state or national level, and showed some signs of marked decline in some shires, although different parts of New South Wales demonstrated different trends. A different picture emerged from the latent diversity measure based on pedigree data, where diversity declined in later periods in all shires and most states, while remaining high at the national level. This was consistent with an increase in the number of varieties grown, but also where the varieties are relatively closely related genetically. The implication of the findings for policies to address diversity appropriately could be significant.
