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Lecture

BMEN 515 Lecture Notes - Trophic Level, Detritivore, Herbivore


Department
Biomedical Engineering
Course Code
BMEN 515
Professor
William Huddleston

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Species that live and interact in an area constitute an ecological community
Ecological communities are not assemblages of organisms that move
together as units when environmental conditions change, rather each species
has unique interactions with its biotic and abiotic environments
Organisms in a community can be divided into trophic levels based on their
source of energy
Trophic level: consists of the organisms whose energy source has passed
through the same # of steps to reach them
Photosynthesizers=primary producers
All nonphotosynthetic organisms (heterotrophs) consumer either directly or
indirectly the energy-rich organic molecules produced by primary producers
Primary consumers: eat plants constitute a trophic level called herbivores
Secondary consumers: eat herbivores
Decomposers: detrivores eat dead bodies
Organisms that obtain food from more than one trophic level are omnivores
Sequence of interactions in which a plant is eaten by an herbivore, which is in
turn eaten by a secondary consumer-food chain; food web
Most communities have 3-5 trophic levels; biomass: weight of living matter
in most terrestrial ecosystems photosynthetic plants dominate, both in terms
of the energy they represent and the biomass they contain
mammals may consume 30-40 percent of the annual aboveground grassland
plant biomass; insects may consume an additional 5=15 percent; soil
organisms 6-40 percent of the belowground biomass in grasslands
in aquatic ecosystems, dominant photosynthesizers are bacteria and
protists ; high rates of cell division
predators restrict habitat and geographic distribution of their prey
austrialian biogeographic region is home to a birds- megapodes (mound-
builders) that don’t incubate eggs; lay eggs in a mound of decomposing
vegetable material; warmed by decomposition; parent visits regularly to add
or remove decaying material for temperature
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