#13 - Communities

#13 - Communities - number of species present and their...

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1 Communities • An assemblage of species that occur together in space and time • Community ecology seeks to determine whether there are natural rules that structure communities, and if so what those rules are and how they apply Descriptors of communities • Species richness – The total number of species within the community – The number of species an investigator actually finds is, to some extent, a function of the intensity of sampling
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2 Two mathematical ways of expressing diversity • Simpson’s index (top) • Shannon’s index (below) • Both incorporate the
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Unformatted text preview: number of species present and their relative abundance D max = S Equitability The degree of variation in abundance of the species within a community is encapsulated in the concept of equitability D max = S Rank abundance Rank abundance plots show how the relative numbers of particular species relate to their abundance (species) rank the most abundant species is rank 1, the second-most abundant is rank 2, etc. the relative abundance (y-axis) is the proportion of all individuals made up of each species Figure 16.5a, page 473...
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This note was uploaded on 04/24/2008 for the course BIOL 216 taught by Professor Baker during the Spring '08 term at Clark University.

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#13 - Communities - number of species present and their...

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