Biodiversity

Biodiversity is the degree of variation of life forms within a given species, ecosystem, biome, or an entire planet. Biodiversity is a measure of the health of ecosystems. Biodiversity is in part a function of climate. In terrestrial habitats, tropical regions are typically rich whereas polar regions support fewerspecies.
Rapid environmental changes typically cause mass extinctions. One estimateis that less than 1% of the species that have existed on Earth areextant.[1]
Since life began on Earth, five major mass extinctions and several minor events have led to large and sudden drops in biodiversity. The Phanerozoic eon (the last 540 million years) marked a rapid growth in biodiversity via the Cambrian explosion—a period during which the majority of multicellular phylafirstappeared.[2] The next 400 million years included repeated, massive biodiversity losses classified as mass extinction events. In the Carboniferous,rainforest collapse led to a great loss of plant and animal life.[3] The Permian–Triassic extinction event, 251 million years ago, was the worst; vertebrate recovery took 30 million years.[4] The most recent, the Cretaceous–Paleogene extinction event, occurred65 million years ago, and has often attracted more attention than others because it resulted in the extinction of the dinosaurs.[5]
The period since the emergence of humans has displayed an ongoing biodiversity reduction and an accompanying loss of genetic diversity. Named theHolocene extinction, the reduction is caused primarily by human impacts, particularly habitat destruction. Conversely,biodiversity impacts human health in a number of ways, both positively and negatively.[6]
The United Nations designated 2011-2020 as the United Nations Decade on Biodiversity.
Contents  [hide]  * 1 Etymology * 2 Definitions * 3 Distribution * 3.1 Latitudinal gradients * 3.2 Hotspots * 4 Evolution * 4.1 Evolutionary diversification * 5 Human benefits * 5.1 Agriculture *5.2 Human health * 5.3 Business and industry * 5.4 Leisure, cultural and aesthetic value * 5.5 Ecological services * 6 Number of species * 7 Species loss rates * 8 Threats * 8.1 Habitat destruction * 8.2 Introduced and invasive species * 8.2.1 Genetic pollution * 8.3 Overexploitation * 8.4 Hybridization, genetic pollution/erosion and food security* 8.5 Climate change * 8.6 Human overpopulation * 9 The Holocene extinction * 10 Conservation * 11 Protection and restoration techniques * 11.1 Resource allocation * 12 Legal status * 12.1 International * 12.2 National level laws * 13 Analytical limits * 13.1 Taxonomic and size relationships * 14 See also * 15 References * 16 Further reading *17 External links * 17.1 Documents * 17.2 Tools * 17.3 Training material * 17.4 Resources |
-------------------------------------------------
[edit]Etymology
The term biological diversity was used first by wildlife scientist and conservationist Raymond F. Dasmann in the 1968 lay book A Different Kind of Country[7] advocating conservation. The term was widely adopted only after morethan a decade, when in the 1980s it came into common usage in science and environmental policy. Thomas Lovejoy, in the foreword to the book Conservation Biology,[8] 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." Bythe early 1980s TNC's Science program and its head, Robert E. Jenkins,[9] 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 1986 National Forum on Biological Diversity organized by the National Research Council(NRC). It first...