EcoSimR (version 0.1.0)

pianka: Pianka Niche Overlap Metric

Description

Takes a resource utilization matrix as input and returns the average pairwise Pianka's niche overlap index.

Usage

pianka(m = matrix(rpois(80, 1), nrow = 10))

Arguments

m

a matrix of resource utilization values.

Value

Returns the average pairwise niche overlap.

Details

Pianka's niche overlap index is averaged over each unique species pair. The index is symmetric, with a normalization term in the denominator for the overlap between species 1 and 2. Values of Pianka's niche overlap index close to 0.0 reflect usage of exclusive resource categories, whereas values close to 1.0 reflect similar resource utilization spectra. $$O_{jk}=O_{kj}=\frac{\sum _n^i{p}_{ij}{p}_{jk}}{\sqrt{\sum _n^i{p}_{ij}^2\sum _n^i{p}_{ik}^2}}$$

References

Pianka, E. 1973. The structure of lizard communities. Annual Review of Ecology and Systematics 4:53-74.

Winemiller, K.O. and E.R. Pianka. 1990. Organization in natural assemblages of desert lizards and tropical fishes. Ecological Monographs 60: 27-55.

See Also

czekanowski niche overlap index.

Examples

obsOverlap <- pianka(m=matrix(rpois(40,0.5),nrow=8))