The area on Earth considered to have the greatest biodiversity is the Tropical Andes region covering 1,258,000 km² (485,716 miles²) and running through Venezuela, Colombia, Ecuador, Peru, Bolivia, Chile and a small area of northern Argentina. So far, 45,000 species of vascular plants have been described (15-17% of world's species) as well as 1,666 bird species, 414 mammal species and 1,309 reptile and amphibian species. The Tropical Andes is called an environmental hotspot which is a concept used to determine priorities among terrestrial ecosystems. British ecologist Norman Myers first defined the biodiversity hotspot concept in 1988. Two factors are considered for hotspot designation. Hotspots are regions that harbour a great diversity of endemic species and, at the same time, have been significantly impacted and altered by human activities. Plant diversity is the biological basis for hotspot designation given the fact that most other forms of life depend upon them. To qualify as a hotspot, a region must support 1,500 endemic plant species, 0.5 percent of the global total. Existing primary vegetation is the basis for assessing human impact in a region; to qualify as a hotspot, a region must have lost more than 70 percent of its original habitat. Marine systems are not included in the 'hotspot' concept.