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28 - Assimilated efficiency = assimilated energy/ingested...

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BIO LECTURE NOTES (3/13/09) The number of species in a community may depend on predation o Keystone predator River communities show a top- down structure o Trophic cascade removing large fish has an effect on populations (pos and neg effects) Ecosystems The flow of energy is a central organizing theme in community ecology o Food chains o Ecosystems o Trophic levels – category of food chain that whole organisms share in common The efficiency of energy transfer from one trophic level to the next varies among communities (eaten -> assimilated -> converted to more predators) o Predators and herbivores will not find and consume all prey Exploitation efficiency = ingested prey/prey o Indigestible parts of plants and animals are not assimilated
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Unformatted text preview: Assimilated efficiency = assimilated energy/ingested prey A lot of the energy will be used in respiration o Some assimilated energy is used for work and respiration, some individuals die- Ecological efficiency = assimilated energy/prey- Net production efficiency = growth & reproduction/ assimilated energy • Food-web chain length is proportional to ecosystem size in lakes o The ecosystem-size hypothesis predicts that the food-chain length of a community will increase with increasing ecosystem size, no matter what the productivity o If productivity was unimportant, then there should be no change in food-chain length with increasing productivity, no matter how large the ecosystem...
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