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Chapter 17

BIOLOGY 2F03 Chapter Notes - Chapter 17: Ecophysiology, Cleaner Fish, Fynbos

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D R.Kajura

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Chapter 17 - Species Interactions and Community Structure
Food Web: the feeding relationships of communities
Ecological Networks: description of the interactions that occur among co-occurring
species in a community
-Based on ecological process in which organisms participate in
-Three main categories: trophic networks, host-parasitoid networks, and mutualistic
oTrophic networks: interactions based upon feeding relationships (ex food
oHost-parasitoid networks: the interconnectedness of host an their parasites,
diseases and parasitoids
oMutualistic network: interactions such as pollination and mycorrhizae, and
emphasize that most mutualism involve many species and differing
degrees of specialization
Community Assembly Rules: can occur within or across trophic levels, and describe the
processes that limit or promote coexistence
-Originally presented as a specific set of rules that governed what species could, or
not co-occur  now used in a more general way
17.1 - Ecological Networks Across Trophic Boundaries: Food Webs
Incorporate aspects the biology of the organisms & the direction of movement of energy
and resources within or between communities.
Example: Food web on Bear Island
-Primary producers: terrestrial plants and aquatic algae
oFeed on: terrestrial & aquatic invertebrates
Consumed by: birds
Birds attacked by arctic foxes
Arctic foxes feed on marine mammals and dung of polar
Polar bears eat seals and beached marine mammals
Food webs are said to be incomplete because people focus more on the larger organisms
in the systems
Detailed Food Webs Reveal Great Complexity
Kirk Winemiller: studied aquatic food webs at two locations with 20-88 fish species
-Crazy complex diagrams  simplifying food web structure, focusing on strongest
feeding relationships identifies and emphasizes the more biologically significant
trophic interactions
Feeding Relationships: Cross Community Boundaries
Ralph Bird: published a paper detailing the feeding relationships among species in each
of the major community types of the parkland
-Important points of the figures in his paper:
o# of connections in each community does not appear to be particularly
complex but they do not have the species involved listed but instead list
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