This polygon shapefile represents World Wildlife Fund (WWF) global terrestrial ecoregions. Ecoregions are defined as relatively large areas of land or water in the world containing a characteristic set of natural communities that share a large majority of their species, dynamics, and environmental conditions. This data set contains all terrestrial ecoregions, which include those of the Global 200. Global 200 ecoregions are a collection of the Earth's most outstanding and diverse terrestrial, freshwater, and marine habitats where the Earth's biological wealth is most distinctive and rich, where its loss will be most severely felt, and we must protect if we are to preserve the web of life. For more information, contact http://www.worldwildlife.org. This layer is part of the 2014 ESRI Data and Maps collection for ArcGIS 10.2. World Wildlife Fund Terrestrial Ecoregions provides a global view of terrestrial ecoregions defined by the World Wildlife Fund Conservation Science Program, and can be used for geographic display and analysis at national and world levels. World Wildlife Fund; ESRI. (2014). World Wildlife Fund Terrestrial Ecoregions. ESRI. Available at: http://purl.stanford.edu/fk938jc7981