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Chapter 55: Community Ecology (Lecture Notes)

Biological Sciences
Course Code
Kamini Persaud

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Chapter 55: Community Ecology
Mar 31/2011
What are ecological communities?
An ecological community consists of all the species that live and interact in a given
Species tend to be grouped together
However, different species can lives with various species, overlapping and underlying
depending on the area
Species are categorized based on energy source
Food chains are developed through food webs
Most communities share the fact that they have only 3-5 trophic levels
oWhy? because as energy (BIOMASS) passes through different levels, some
energy is lost in different ways
oMost energy is held at the primary producersprimary
consumerssecondary consumers
oVariations of biomass depends on community
What processes influence community structure?
Types of Ecological interactions:
1.Predationoscillating effect (if there are more predators, extinction of
prey might is common. If there are more prey and very little predators,
the prey species will be over-crowded)
2.Parasitesfeed on the host without killing it
3.Competitioninfluences abundance and distribution of species; two
organisms using the same resource that is insufficient to supply needs of
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