Species density (a relative measure of species richness) decreases poleward. Functional diversity is highest in the Tropical Eastern Pacific and at dispersed hotspots at a range of latitudes. Color classifications differ between maps due to different ranges and distributions of diversity values. Minimum and maximum observed values are provided in the key for each plot as effective numbers per 500 square meters
The number of different species in an ecosystem — what researchers call “species richness” — has dominated the scientific view of global biodiversity patterns since the days of Darwin and Linnaeus. It has also long been used as a biological basis for management of imperiled ecosystems.