At present human well-being, and particularly food security, depends on a relatively small base at the species level. Failure of one individual crop can have catastrophic human consequences (e.g. potato blight). Species directly used by humans in productive systems on a large scale consist of a few tens of domesticated animal species, a few hundred crop plant species (with the exception of ornamental and horticultural plants), and a few tens of major plantation timber species.

Genetic diversity within these domesticated and cultivated species is crucial to maintaining the goods and services they provide, including properties such as high yields, resistance to pests and diseases, and ability to adapt to different and changing environmental conditions.

Genetic diversity within crops in farming systems is usually described by varieties, which can be either local or traditional (land races) or improved. Unfortunately, variation at varietal level, whether varieties are named or unnamed, is very hard to quantify. There is no standard as to how much difference, or what kind, is enough to separate one variety from another. Often differently named seed strains of crops, for example, may prove to have no discernible difference when they are actually compared as plants.
In livestock species the pattern is similar to that in crops, with genetic diversity usually being described in terms of breed diversity. However, livestock breeds are less genetically uniform than plant varieties and it is common for animals from different breeds to be crossed, often in an unsystematic and unrecorded manner. Moreover, the way in which “breeds” are delineated depends to a considerable extent on cultural factors that do not always correspond well to underlying genetic differences.

Ex situ crop collections are a key tool for the conservation of crop plant varieties and their wild varieties, and help to ensure that genetic diversity is not lost with the globalisation of agriculture. Data from such collections may be developed as an indicator to shows changes in the crop genetic diversity available for sustainable agricultural production. This data may also reflect changes in the efforts to collect specimens and conserve diversity.

Ex situ collections are far less well developed as a method for conserving livestock breeds. The maintenance of genetic diversity in livestock remains largely dependent on ongoing use. FAO publishes status and trends which present an analysis based on the risk status of all the breeds for which population data are available.