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Communities and Ecosystems

Communities and Ecosystems. ESC 556 week 7. Community. Collection of species populations Members from most kingdoms Linked in a web Mainly predator/prey Environment & habitat / Dominant species Lake/grassland Sizes. Habitats and Niches. Habitat: A collection of niches Habitat

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Communities and Ecosystems

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  1. Communities and Ecosystems ESC 556 week 7

  2. Community • Collection of species populations • Members from most kingdoms • Linked in a web • Mainly predator/prey • Environment & habitat / Dominant species • Lake/grassland • Sizes

  3. Habitats and Niches • Habitat: A collection of niches • Habitat • Physical space where an organism lives • Microhabitats • Niche • The unique position occupied by a particular species in a community – ecological role • Each niche unique • Occupy overlapping BUT different niches • Fundamental vs. realized niche • Resource partitioning • Darwin’s finches

  4. Darwins’ Finches

  5. Patchiness • Distribution patterns • Random • Aggregated • Conditions & resources not evenly distributed • Temporal variability • Intraspecific & interspecific competition • Events • Gradient • Regular

  6. Plankton patchiness • Horizontal, temporal & vertical variability • Physical - Water movements • Biological – plankton related • Light – dark cycle • Gamete concentration • Predator – prey interactions

  7. Trophic interactions and productivity • Primary producers, consumers, decomposers • Rule of 10% • Different communities w/ different# of trophic levels • NPP

  8. Net Primary Production

  9. Trophic interactions and productivity • Guilds • Overlapping niche requirements • Keystone species • Limpets • Dominant • Numerical or biomass abundance • Opportunistic species, specialization, generalists

  10. Measuring Productivity • 6CO2 + 6H2O  C6H12O6 (glucose) + 6O2 • Increase in biomass over a fixed time period  NPP • Plankton

  11. Measuring Productivity • Chylorphyll abundance • Secondary production

  12. Comparative Ecosystem Productivity • Productivity determinants • Light, temperature, rainfall, nutrients • Tropics, higher latitudes, deserts • Photosynthetic efficiency • 1-2 % in terrestrial ecosystems – 0.5 % in aquatic habitats • Conditions for plant growth not met • More secondary production in oceans • Detritivores

  13. Trophic Interactions & Pollution • Material transfer • Minerals, vitamins etc. • Pollutants • Heavy metals, organic chemicals, some light elements • Bioconcentration • Biomagnification • Biotransformation • Mercury  methyl mercury

  14. Mercury Pollution • Minimata disease, brain damage, kidney damage etc. • Organic methyl mercury • Bioconcentration & Biomagnification

  15. Succession • The change in composition and form of vegetation • Immature  mature/self-sustaining • Primary Succession • Pioneer species • Xerarch vs. hydrarch succession • Secondary succession • Climax community

  16. Xerarch vs. hydrarch succession

  17. Succession

  18. Biodiversity • Species & genetic & ecosystem diversity  biodiversity • Ecological diversity • Species diversity • Genetic diversity • Species richness vs. species diversity • Tropical forests, coral reefs and tropical lakes • Genetic diversity • Habitat destruction, pollution and agricultural practices

  19. Stability and Resilience • Stability – environmental change • Persistence, constancy, resilience • High diversity = high stability? • Tropical rainforest vs. grasslands

  20. Biogeography • Study of the distribution of organisms • Historical & Ecological • Vicariant and dispersal distribution • Endemic taxa • Six major zones

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