Biodiversity is shorthand for biological diversity and refers to the variety of genes, species and ecosystems which are part of nature.
All life is part of one great, interdependent system.
Scientists classify living organisms into separate species based upon their physical form and the potential to interbreed and produce viable, fertile offspring. Consider horses and donkeys. Horses and donkeys are therefore separate species. Two painted donkeys Photo courtesy Department of the Interior, BLM Estimates of the total number of species on the Earth range from 5 million to 100 million. Species diversity is the total number of species found within a given area.