Number of Endemic Species by Freshwater Ecoregion

Number of freshwater endemic species, by freshwater ecoregion.

The map of the number of freshwater endemic species shows the number of endemic fish, freshwater turtles, crocodiles, and amphibians found in each freshwater ecoregion. To calculate the total number of endemic species by ecoregion, we simply added the number of endemic species in these four taxonomic groups. Fish endemics are from Abell et al. (2008). Extirpated fish species are included in these tallies, but resolved extinct species, as determined by the Committee on Recently Extinct Organisms, and introduced species are excluded. Data on amphibian species were generated from distribution maps for 5,640 amphibian species gathered by the Global Amphibian Assessment (IUCN et al. 2006). Data on freshwater turtles were generated from species distribution maps provided by Dr. Kurt A. Buhlmann, the Savannah River Ecology Laboratory, University of Georgia, United States; and the International Union for Conservation of Nature–Species Survival Commission (IUCN-SSC) and Conservation International/Center for Applied Biodiversity Science (CI/CABS) Global Reptile Assessment (preliminary results).

For both amphibians and turtles, species distribution maps were used to determine endemism by ecoregion. If at least 90 percent of a species’ range occurred in only one ecoregion, that species was said to be endemic. Some ecoregions with a long and narrow shape may have an overestimation of species given the way the range polygons were drawn. This is particularly true for the Amazonas High Andes ecoregion (312), where the mountain range has been used as a range boundary for hundreds of species. The two ecoregional endemic crocodiles were the Cuban crocodile (Crocodylus rhombifer) in the Cuba–Cayman Islands ecoregion (211), and the Chinese alligator (Alligator sinensis) in the Lower Yangtze ecoregion (766). These were added to the total tally for the respective ecoregions.

These data were derived by The Nature Conservancy, and were displayed in a map published in The Atlas of Global Conservation (Hoekstra et al., University of California Press, 2010). More information at http://nature.org/atlas.

Our primary data sources for the maps were the following:
Abell, R., M. L. Thieme, C. Revenga, M. Bryer, M. Kottelat, N. Bogutskaya, B. Coad, et al. 2008. Freshwater ecoregions of the world: A new map of biogeographic units for freshwater biodiversity conservation. BioScience 58, no. 5: 403–414.

Buhlmann, K. A., T. B. Akre, J. B. Iverson, D. Karapatakis, R. A. Mittermeier, A. Georges, A. G. J. Rhodin, P. P. van Dijk, and J. W. Gibbons. 2007. A global analysis of tortoise and freshwater turtle distributions. Data from the preliminary results of the Global Reptile Assessment. International Union for Conservation of Nature–Species Survival Commission (IUCN-SSC), Conservation International/Center for Applied Biodiversity Science (CI/CABS), and Savannah River Ecology Laboratory, University of Georgia, Athens, Georgia, USA.

International Union for Conservation of Nature (IUCN), Conservation International, and NatureServe. 2006. Global Amphibian Assessment. Available at www.iucnredlist.org/amphibians. Digital media.