In total, this updated analysis reveals the existence of 34 biodiversity hotspots, each holding at least 1,500 endemic plant species, and having lost at least 70 percent of its original habitat extent. Overall, the 34 hotspots once covered 15.7 percent of the Earth's land surface. In all, 86 percent of the hotspots' habitat has already been destroyed, such that the intact remnants of the hotspots now cover only 2.3 percent of the Earth’s land surface.
Results from the updated analysis:
Endemic Plant Species
Endemic Vertebrate Species
Between them, the hotspots hold at least 150,000 plant species as endemics, 50 percent of the world's total. The total number of terrestrial vertebrates endemic to the hotspots is 11,980, representing 42 percent of all terrestrial vertebrate species. Reptiles and amphibians, are more prone to hotspot endemism than are the more wide-ranging mammals and birds, but the overall similarity between taxonomic groups is remarkable. Overall, 22,022 terrestrial vertebrate species call the hotspots home, 77 percent of the world's total. With rapid increases in data quality and synthesis, we can now derive species lists for each hotspot, above and beyond estimated species numbers. The current analysis also includes the first assessment of inland fishes across all hotspots. Although most current statistics are likely underestimates — because almost 200 freshwater fish species are discovered each year — the hotspots already hold 29 percent of the world's freshwater fish species as endemics, with 55 percent of species occurring.
While the 34 hotspots clearly hold astounding levels of species endemism, this is not sufficient to describe the extent to which they represent the history of life. This is important because it could be argued that measures of biodiversity at higher taxonomic levels than the species better represent evolutionary potential, ecological diversity, and the range of options for future human use. In the current analysis, we therefore measure hotspot endemism at the higher taxonomic levels of genera and families, and find an extremely high concentration of biodiversity at these levels, even compared to what we would expect based on their levels of species endemism.
Three major conclusions emerge from this updated hotspots analysis. First, it is clear that the hotspots concept is solidifying. This update results in few major modifications to the broad global picture of hotspots. Second, the amount of biodiversity contained in the hotspots is extremely high. More than half of the planet's species are endemic to only 16 percent of its land area. Based on the evidence from terrestrial vertebrates, it seems that the overall number of species occurring in the hotspots is much greater — approaching four-fifths. If we consider only the extent of remaining habitat — 2.3 percent of the planet's land surface — these numbers are even more remarkable. Finally, and most importantly, hotspots provide us with the real measure of the conservation challenge. Unless we succeed in conserving this small fraction of the planet’s land area, we will lose more than half of our natural heritage.