Biodiversity is the degree of variation of life forms within a given ecosystem, biome, or an entire planet. Biodiversity is one measure of the health of ecosystems. Life on Earth today consists of many millions of distinct biological species. The United Nations declared the year 2010 as the International Year of Biodiversity. Biodiversity is not consistent across the Earth. In the terrestrial context for example, tropical regions are typically rich whereas polar regions support fewer species. Rapid environmental changes typically cause extinctions. 99.9 percent of species that have existed on Earth are now extinct. Since life began on Earth, five major mass extinctions have led to large and sudden drops in Earthly biodiversity. The Phanerozoic eon (the last 540 million years) marked a rapid growth in biodiversity in the Cambrian explosion—a period during which nearly every phylum of multicellular organisms first appeared. The next 400 million years was distinguished by periodic, massive biodiversity losses classified as mass extinction events. The Permo-Triassic Extinction, 251 million years ago was the worst, devastating life in the sea and on land; vertebrate recovery took 30M years.. The most recent, the Cretaceous–Tertiary extinction event, occurred 65 million years ago, and has attracted more attention than all others because it killed the nonavian dinosaurs. The period since the emergence of humans has displayed an ongoing reduction in biodiversity. Named the Holocene extinction, the reduction is caused primarily by human impacts, particularly the destruction of plant and animal habitat. In addition, human practices have caused a loss of genetic diversity. Biodiversity's impact on human health is a major international issue Etymology
The term was used first by wildlife scientist and conservationist Raymond F. Dalesman in the 1968 lay book A Different Kind of Country advocating conservation. The term was widely adopted only after more than a decade, when in the 1980s it came into common usage in science and environmental policy. Use of the term by Thomas Lovejoy, in the foreword to the book Conservation Biology, introduced the term to the scientific community. Until then the term "natural diversity" was common, introduced by The Science Division of The Nature Conservancy in an important 1975 study, "The Preservation of Natural Diversity." By the early 1980s TNC's Science program and its head, Robert E. Jenkins, Lovejoy and other leading conservation scientists at the time in America advocated the use of "biological diversity". The term's contracted form biodiversity may have been coined by W.G. Rosen in 1985 while planning the National Forum on Biological Diversity organized by the National Research Council (NRC) which was to be held in 1986, and first appeared in a publication in 1988 when entomologist E. O. Wilson used it as the title of the proceedings of that forum. Since this period both the term and the concept have achieved widespread use among biologists, environmentalists, political leaders, and concerned citizens. The term is sometimes used to reflect concern for the natural environment and nature conservation. This use has coincided with the expansion of concern over extinction observed in the last decades of the 20th century. A similar concept in use in the United States is "natural heritage." Less scientific, it predates the others and is more accepted by the wider audience interested in conservation. Unlike biodiversity, it includes geology and landforms (geodiversity).
A Sampling of fungi collected during summer 2008 in Northern Saskatchewan mixed woods, near LaRonge is an example regarding the species diversity of fungi. In this photo, there are also leaf lichens and mosses. "Biological diversity" or "biodiversity" can have many interpretations and it is most commonly used to replace the more clearly defined and long established terms, species diversity and...
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