Genetic diversity occurs within and between populations of species as well as between species.
Species diversity refers to the variety of living species. Ecosystem diversity relates to the variety of habitats, biotic communities, and ecological processes, as well as the tremendous diversity present within ecosystems in terms of habitat differences and the variety of ecological processes. What constitutes an occurrence depends on the biology of the species. For birds, a nesting pair would for most species constitute an occurrence, while for annual plants, an occurrence may include thousands of individuals.