TrophicSimilarity {cheddar} | R Documentation |
A measure of trophic overlap between nodes in a community.
TrophicSimilarity(community) MeanMaximumTrophicSimilarity(community)
community |
an object of class |
TrophicSimilarity
computes ‘trophic similarity’ (I) as defined
by Martinez (1991). For each pair of nodes, I = c/(a+b+c), where a is the
number of resources and consumers unique to one node, b is number of resources
and consumers unique to the other node and c is the number of resources and
consumers common to both nodes. Where two nodes have exactly the same set of
resources and consumers, I = 1. Where two nodes have no resources or consumers
in common, I = 0.
Williams and Martinez (2000) defined the mean maximum trophic similarity as the sum of the largest value in each column of I (excluding the diagonal), divided by the number of nodes.
TrophicSimilarity
returns a matrix
with
NumberOfNodes
rows and columns. MeanMaximumSimilarity
returns
a number.
Lawrence Hudson
Martinez, N. D. (1991) Ecological Monographs 61, 367–392.
Williams, R. J. and Martinez, N. D. (2000) Nature 404 180–182.
PredationMatrix
, NumberOfNodes
,
TrophicSpecies
data(TL84) I <- TrophicSimilarity(TL84) I MeanMaximumTrophicSimilarity(TL84)