Bio153_Lecture20_Biodiversity_sv

Bio153_Lecture20_Biodiversity_sv - Biodiversity 1. 2....

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Biodiversity and Conservation Biodiversity 1. diversity of ecosystems 2. diversity/variety of species - species richness - relative abundance 3. genetic variation within each species Biodiversity • Diversity of organisms in a given area • Two elements: –In t e r specific variation or species diversity (studied by ecologists) –In t ra specific variation or gene diversity (studied by geneticists) Biodiversity • Biologically diverse ecosystems are in general more stable than simple ones – Species richness characterizes an ecosystem’s biodiversity • Two factors are important in promoting biodiversity – Ecosystem size – Latitude • Larger ecosystems… • A reduction in an ecosystem size, will reduce the number of species it can support – extinction may occur Ecosystem Size • The number of species in the tropics is far more than that in the arctic region Latitude • Two principal reasons:
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• In undisturbed ecosystems extinction rates have been estimated at 1 species lost every 10 years • During the past century massive habitat destruction, particularly in tropical regions, has increased rates of extinction to at least 4,000-6,000 species per year Biodiversity and Extinctions Golden lion tamarin Biodiversity Crisis: Major Causes of Species Extinction 1. habitat destruction 2. overexploitation of species 3. introduced species: 4. pollution Biggest threat to biodiversity Single most important cause Undisturbed tropical forest in Amazonia Logged rainforest in Amazonia HABITAT DESTRUCTION Figure 58.1 Disappearance of Forests
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Destruction of Wetlands Wetlands hold water Cost of flood damage: 33 trillion US$ in one year Habitat Fragmentation • Habitat fragmentation occurs when a large expanse of habitat is transformed into a number of smaller patches HABITAT FRAGMENTS AND SURVIVAL - the proportion of a habitat patch subject to detrimental edge effects increases
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This note was uploaded on 02/01/2012 for the course BIOLOGY 153 taught by Professor Dr.arts during the Fall '10 term at University of Toronto- Toronto.

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Bio153_Lecture20_Biodiversity_sv - Biodiversity 1. 2....

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