What is Biodiversity?
Biodiversity was first defined as taxonomic diversity – the number of species. More recently, biodiversity has been broadened to include biological and geographic entities such as genetic diversity (genes, chromosomes), taxonomic diversity (species, genera, families, phyla, etc.) and biogeographic diversity (biogeographic regions, landscapes, ecosystems, habitats). Biodiversity always refers to the genetic, or taxonomic variability, within a specific area or region.
Biodiversity on Earth
The biodiversity of earth is astounding. Our planet supports between 3 and 30 million species of plants, animals, fungi, protozoa, and bacteria. Despite two centuries of research, systematists have described only about 1.4 million species. The ecology, or role of these species in ecosystems, has been studied for less than one percent. We know more about large, economically important plants and animals than we do about fungi and bacteria, despite their important ecological roles. Only about 200,000 species of fungi have been described of the estimated 1-1.5 million species. In contrast, virtually all of the 9,000 species of birds and 4,500 species of mammals have been described.
Biodiversity of Fungus
Recent research suggests that fungal biodiversity is much higher than previously thought. 145 different species of microfungi have been found in very small samples of fresh and decayed leaves from the forest floor of tropical rainforests. About 29,000 microfungi have been estimated to occur in the United States. The number of macrofungi in the United States has been estimated to range from 5,000 to 10,000 species. Despite their importance, none of the 711 federally listed endangered and threatened species under the jurisdiction of the U.S. Fish and Wildlife Service are fungi.
Loss of Biodiversity
Earth’s biodiversity is rapidly decreasing in response to pollution and habitat destruction as forests are logged, prairies converted to subdivisions, and wet lands drained for development. The 1991 Red List for the former Federal Republic of Germany, for instance, lists 1,037 species of threatened larger fungi (mushrooms, puff balls, etc), 35% of all the larger fungi. No similar comparison is available for microfungi. With the loss of each species, we lose potential sources of new medicines, other chemicals, and food. We also lose links in food webs and critical ecosystem processes that are essential for clean air, clean water, and healthy ecosystems. The air pollution in Western Europe is harmful to the symbiotic fungi that act as extensions of trees’ root systems by absorbing the minerals trees need for growth. The loss of these symbiotic fungi has resulted in the death of millions of trees. The concern about the loss of biodiversity has fostered a number of initiatives to discover, describe, and classify (name) the world’s species. One component in this process is Bioinformatics, which utilizes the catalogues of museum collections to provide baseline data on where species occur, have occurred, and their abundance. Surveys of poorly known regions, or poorly known groups of organisms are another component. There are also attempts to study the interactions among groups of organsisms in order to identify critical "keystone" species responsible for controlling the functioning and structure of ecosystems.