16 - BIO LECTURE NOTES (2/13/09) Biodiversity and...

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BIO LECTURE NOTES (2/13/09) Biodiversity and conservation How many species are living today? o Approx 1.5 million species have been cataloged to date o Two general approaches have been used to estimate the total number of species: 1) surveys of species-rich groups at smalls ties ( taxon-speceifioc surveys ) 2) surveys of all he species present in a particular region ( all-taxa surveys ) Taxon-Specific Surveys o researchers estimated the number of insect species living in the canopy of a single tropical tree. They identified over 900 species of beetles alone o from these data, they estimated that the world total of arthropod species exceeds 30 million species All-Taxa Surveys o The first effort tot find and catalog all of the species present in a large area, the Great Smoky Mountains National Park, is now under way o The survey started in 199 and will be finished in 2015 o To date, over 650 new species have been discovered Where is biodiversity highest? o In most taxonomic groups, species richness is highest in the tropics and declines toward the poles. The tropical rain forests are particularly species rich o Hotspots are regions that are much more species rich than others o In addition, some regions of the world have a high proportion of
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16 - BIO LECTURE NOTES (2/13/09) Biodiversity and...

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