Species diversity is one of the three main levels of biodiversity, the others being ecosystem and genetic diversity. This indicator is linked to other indicators which have implications for biodiversity. No international targets exist for this indicator. The underlying concepts are well articulated, although countries may use variations of terminology. Extinction means no longer existing anywhere in the world, at least in the wild.
Extirpation means no longer existing in the country or area of interest.
Threatened species relates to Class, the third highest level in the taxonomic hierarchy, after kingdom and phylum. For each class, calculate the percentage of threatened native species against total native species in this class. Countries may wish to make separate compilations for each of the 4 sub-indicators of species at risk of extinction, and species at risk of extirpation. This indicator is a State indication of biodiversity. Genetic variation within some species may be as important as differences between species, but may be missed by reporting at the species level alone.