biodiversity

Topics: Biodiversity, Extinction, Invasive species Pages: 14 (8804 words) Published: October 29, 2014

Biodiversity
From Wikipedia, the free encyclopedia

Coral reefs are amongst the most diverse ecosystems on earth.

Rainforests are an example of biodiversity on the planet and typically possess a great deal of species diversity. This is the Gambia River in Senegal's Niokolo-Koba National Park. Biodiversity is the degree of variation of life.[1] It is a measure of the variety of organisms present in different ecosystems. This can refer to genetic variation, ecosystem variation, or species variation (number of species)[1] within an area, biome, or planet. Terrestrial biodiversity tends to be highest near the equator,[2] which seems to be the result of the warm climate and high primary productivity.[3] Biodiversity is not distributed evenly on Earth. It is the richest in the tropics. Marine biodiversity tends to be highest along coasts in the Western Pacific, where sea surface temperature is highest and in the mid-latitudinal band in all oceans. There are latitudinal gradients in species diversity.[4] Biodiversity generally tends to cluster in hotspots,[5] and has been increasing through time[6][7] but will be likely to slow in the future.[8]Rapid environmental changes typically cause mass extinctions.[9][10][11] One estimate is that <1%–3% of the species that have existed on Earth are extant.[12]The earliest evidences for life on Earth are graphite found to be biogenic in 3.7 billion-year-old metasedimentary rocks discovered in Western Greenland[13] and microbial mat fossils found in 3.48 billion-year-old sandstone discovered in Western Australia.[14][15] 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 phyla first appeared.[16] 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.[17] The Permian–Triassic extinction event, 251 million years ago, was the worst; vertebrate recovery took 30 million years.[18] The most recent, the Cretaceous–Paleogene extinction event, occurred 65 million years ago and has often attracted more attention than others because it resulted in the extinction of the dinosaurs.[19]The period since the emergence of humans has displayed an ongoing biodiversity reduction and an accompanying loss of genetic diversity. Named the Holocene 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.[20]The United Nations designated 2011–2020 as the United Nations Decade on Biodiversity. Contents

1 Etymology2 Definitions3 Distribution
3.1 Latitudinal gradients3.2 Hotspots4 Evolution and history 4.1 Evolutionary diversification5 Biodiversity and ecosystem services 5.1 The balance of evidence
5.1.1 Services enhanced by biodiversity
5.1.1.1 Provisioning services5.1.1.2 Regulating services5.1.2 Services with mixed evidence 5.1.2.1 Provisioning services5.1.2.2 Regulating services5.1.3 Services for which biodiversity is a hindrance 5.1.3.1 Provisioning services5.1.3.2 Regulating services5.1.4 Services for which there is insufficient data to draw conclusions 5.1.4.1 Provisioning services5.1.4.2 Regulating services5.2 Biodiversity and agriculture5.3 Biodiversity and human health5.4 Biodiversity, business and industry5.5 Biodiversity, leisure, cultural and aesthetic value5.6 Biodiversity and ecological services6 Number of species7 Species loss rates8 Threats 8.1 Habitat destruction8.2 Introduced and invasive species

8.2.1 Genetic pollution8.3 Overexploitation8.4 Hybridization, genetic pollution/erosion and food security8.5 Climate change8.6 Human overpopulation9 The Holocene...
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