Takes a niche utilization matrix returns the variance of the Czekanowski niche overlap index
a matrix of resource utilization values.
A large value for variance implies that some species pairs show high niche overlap and others show low niche overlap. A low value for variance implies that niche overlap (high or low) is very similar among all species pairs.
Returns the variance of the average pairwise niche overlap.
The resource utilization matrix (rows = species, columns = discrete resource categories) may include zeroes, but no negative numbers or missing values. Relative resource within a species is first calculated, so the rows need not sum to 1.0.
Winemiller, K.O. and E.R. Pianka. 1990. Organization in natural assemblages of desert lizards and tropical fishes. Ecological Monographs 60: 27-55.
czekanowski niche overlap index.