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Island Biogeography

Island Biogeography. Dan Simberloff and Mangrove Islands. Simberloff’s defaunation experiment on Mangroves. Simberloff’s defaunation experiment on Mangroves. Results from Simberloff’s Experiment. Islands recovered to pre-defaunation number of species, but only 30%

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Island Biogeography

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  1. Island Biogeography

  2. Dan Simberloff and Mangrove Islands

  3. Simberloff’s defaunation experiment on Mangroves

  4. Simberloff’s defaunation experiment on Mangroves

  5. Results from Simberloff’s Experiment Islands recovered to pre-defaunation number of species, but only 30% of original species resident on each island returned after defaunation.

  6. Bracken Fern

  7. Bracken fern stand Australia

  8. Number of species found on Bracken Fern

  9. Speciation – Picture-Winged Drosophila - Hawaii

  10. Professor Axel Meyer – Cichlid Man

  11. Lake Malawi Cichlids Adaptive radiation within cichlid lineages

  12. Ecosystem Ecology

  13. Raymond Lindeman Sir Arthur Tansley

  14. Some Energy Flow Definitions • Gross primary production (GPP) - total fixation of energy by autotrophs - usually just due to photosynthesis, primarily by plants • Net primary production (NPP) = GPP - respiration, autotrophs use some energy for their own growth and that is lost as respiratory heat, so NPP represents what is available to heterotrophs - NPP is often 10% of GPP • Secondary productivity - production of biomass by heterotrophs • Standing crop - amount of biomass of living organisms in a unit of area

  15. P – productivity tn/ha/yr; B – biomass tn/ha; R - solar radiation – kcal/m2/yr

  16. Temperature, Precipitation and Productivity

  17. Limits to Terrestrial Productivity a) shortage of water restricts rate of photosynthesis b) shortage of mineral nutrients slows down rate of production of photosynthetic tissue and the effectiveness of photosynthesis c) temperatures that are lethal or too low for growth d) insufficient depth of soil (deserts, mountain tops) e) incomplete vegetation canopy cover so that much sunlight lands on the ground and not on foliage

  18. Comparison of productivity by a deciduous tree and an evergreen tree

  19. Limits to Aquatic Productivity • Lack of nutrients • Light is limiting – suspended particles in water reduce light penetration • Intensity of grazing

  20. Coastal Upwelling

  21. Light Penetration in Oceanic Waters

  22. Basic ecosystem - nutrient cycling in red, energy flow in grey

  23. Basic Energy Flow

  24. Basic Energy Flow

  25. Energy Flow Expanded

  26. Energy Flow in Different Ecosystems

  27. Transfer Efficiency

  28. 10% Rule for Transfer Efficiency

  29. Consumption Efficiency • CE = food ingested/food produced • How much of prey population that consumer eats • For herbivores – 5% in forests, 25% in grasslands, 50% in phytoplankton ecosystems • For vertebrate predators – 50-100% vertebrate prey; 5% invertebrate prey • For invertebrate predators – 25% invertebrate prey

  30. Assimilation Efficiency • AE = food assimilated/food ingested • How much of prey eaten is digested • AE usually low for herbivores, microbivores, detritivores – 20-50% • AE usually high for carnivores – 80%

  31. Production Efficiency • PE = new biomass produced/food assimilated • How much of prey digested is converted to consumer biomass and used in reproduction – rest is lost as respiratory heat • PE high for invertebrates – 30-40% • Intermediate for ectotherm vertebrates – 10-20% • Low for endotherm vertebrates – 1-2%

  32. Lindeman’s Efficiency • LE = assimilation at trophic level n assimilation at trophic level n – 1 LE examines efficiency of transfer between trophic levels – often assumed to be 10% but…is actually more complex

  33. Light Absorption

  34. Lindeman’s Efficiencies

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