Lecture 14 Biodiversity

Lecture 14 Biodiversity - Lecture 14: Biodiversity &...

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Biodiversity: Shortening of “biological diversity”; a measure of the richness and abundance of life; includes 3 components: genetic diversity (genotypic variation within species), species diversity (the number of species), and ecosystem diversity (number of unique ecosystems). Critics argue that the term biodiversity is so all inclusive as to become meaningless (i.e., it means everything, therefore it means nothing. Genetic Diversity : Columbia River has genetically unique “runs” of salmon that spawn at different times. Species Diversity or Species Richness : the number of unique species inhabiting a given area. Species richness of the earth is unknown; about 1.7-2.0 million species are known to science (i.e. have been formally named with Latin binomials), but true number of species thought to be 5-30 million (Huge discrepancy! Most unknowns are fungi, inverts, bacteria, etc.). Measurement of species richness depends on our definition of a species, but recall that there is an ongoing scientific debate between biological versus phylogenetic species. Species richness increases due to speciation events (i.e. creation of new species via evolutionary diversification). This is extremely slow! Species richness declines through extinction. There have been 5 great extinction events in fossil history. Some biologists believe we are witnessing the 6 th great extinction now due to human impacts. Ecosystem Diversity : unique communities of organisms (e.g. coral reef, redwood forest) Minnesota’s most imperiled ecosystems include tall-grass prairie (99% gone), oak savanna (99% gone), prairie wetlands (90% gone), and red/white pine forest (86% gone) Biodiversity Hotspots : 25 worldwide ecosystems that cover just 1.4% of Earth’s surface, but harbor 44% of all known plants, 36% of all known terrestrial vertebrates, including many endemics (species found nowhere else in the world). These areas have already lost 88% of their natural habitat, and contain 1 B people. Primarily in 3 rd world. Extinction : The complete loss of all living individuals of a given species (e.g. Dodo, Passenger Pigeon, Carolina Parakeet). Extirpation : The elimination of a species from a specific area (but not from everywhere). Bison have been extirpated from Minnesota, but they still live in the wild elsewhere, and in
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This note was uploaded on 04/07/2008 for the course ESPM 1101 taught by Professor Arnold during the Spring '08 term at Minnesota.

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Lecture 14 Biodiversity - Lecture 14: Biodiversity &...

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