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Chapter 55 Notes

Chapter 55 Notes - Chapter 55 Notes Biodiversity and...

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Chapter 55 Notes Biodiversity and Conservation Biology Biodiversity: the diversity of life considered at three levels o Genetic diversity o Species diversity o Ecosystem diversity 55.1 What is biodiversity? Biodiversity can be measured and analyzed at several levels ***To get a complete understanding of the diversity of life, biologists recognize and analyze biodiversity at the genetic, species, and ecosystem level Genetic diversity Genetic diversity : the total genetic information contained within all individuals of a species. o It is measured as the number of relative frequency of all alleles present in a species Species diversity Species diversity is based on the variety of species on Earth Bar coding: the use of a well-characterized gene sequence to identify distinct species, using the phylogenetic species concept Ecosystem diversity Ecosystem diversity: the array of biotic communities in a region along with abiotic components, such as soil, water, and nutrients Change through time How many species are living today? Given that only a fraction of the organisms alive have been discovered to date, how can biologists go about estimating the total number of species on earth? o One approach is based on intensive surveys of species-rich groups at small sites o A second strategy is based on attempts to identify all of the species present in a particular region Taxon-specific surveys All-taxa surveys 55.2 Where is Biodiversity Highest? Tropical rain forests are particularly species rich o Although only 7% of earth’s land area, contain at least 50% of all species present Hotspots of biodiversity and endemism Biodiversity hot spot: regions that are extraordinarily rich in biodiversity Endemic species: species that are found in an area and nowhere else Conservation Hotspots Mapping species richness hotspots and centers of endemism can inspire research on why certain regions contain many species or a high proportion on endemic taxa
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Biologists are studying the geographic distribution of biodiversity as a way of focusing conservation efforts 55.3 Threats to Biodiversity ***Today, species are vanishing faster than at virtually any other time in Earth’s history. Modern rates of extinction are 100 to 1000 times greater than the average, or
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