Biodiversity - PowerPoint PPT Presentation

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Biodiversity

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  1. Biodiversity …refers to the variety of living organisms, genetic diversity, and the types of ecological communities into which they are assembled.

  2. What is biodiversity? species richness (N) species diversity (H’)- weighted measure Shannon-Wiener Index Simpson Index intraspecific diversity- within and between populations ecosystem/biome diversity- vegetative patterns

  3. Patterns of Species Richness • The earth is not uniform. • climate • topography, geology, & soil fertility • structural complexity of habitats

  4. Patterns of Richness • alpha richness- number of species in a relatively small homogeneous area • beta richness- rate of species change across habitats • gamma richness- rate of species change across landscapes

  5. Patterns of Species Richness • species richness is greatest in tropical regions • islands tend to be relatively species poor. • species-area relationship • endemism & vicariance • ecological release

  6. Immediate causes effecting current levels of species diversity. (after McNeely et al. 1995) • exploitation of natural resources • expansion of agriculture • habitat loss and fragmentation • species introductions • pollution • global climate change

  7. Underlying causes effecting current levels of species diversity. (after McNeely et al. 1995) • human social organization • human population growth • patterns of natural resource consumption • global trade • economic systems and policies • inequity of ownership and distribution of wealth

  8. Species Density total number of species occurring anywhere within a given quadrate.

  9. Reptile Species Density Matrix

  10. Amphibian Species Density Matrix

  11. Species Density Contour Maps

  12. Kiester, A.R. 1971. Species density of North American amphibians and reptiles. Syst. Zool.20:127-137. • density increases toward the equator • mammal density is higher in the west while reptiles and amphibians have higher densities in the east. • mammal density is positively correlated with topographic relief • amphibians are positively correlated with topographic relief and annual rainfall • reptiles are negatively correlated with topographic relief

  13. Extinction • mass extinction- a rapid and substantial global decline in species affecting a broad range of taxonomic groups.

  14. Patterns of Species Vulnerability • rare species- human caused rarity may be more devastating because the species are not adapted to low numbers • long lived species- delayed sexual maturity, low fecundity, high juvenile survivorship • keystone species associations-

  15. Endangered Biological Phenomena • Fire • floods • migrating herds

  16. Loss of Ecosystem Function and Disruption of the Evolutionary Process