ecospat (version 2.0)

ecospat.niche.similarity.test: Niche Similarity Test

Description

Run a niche similarity test (see Warren et al 2008) based on two species occurrence density grids.

Usage

ecospat.niche.similarity.test (z1, z2, rep, one.sided=T, rand.type)

Arguments

z1
Species 1 occurrence density grid created by ecospat.grid.clim.
z2
Species 2 occurrence density grid created by ecospat.grid.clim.
rep
The number of replications to perform.
one.sided
If true, perform a one-sided test, otherwise a two-sided test.
rand.type
Type of randomization on the density grids (1 or 2).

Value

Details

Compares the observed niche overlap between z1 and z2 to overlaps between z1 and random niches (z2.sim) as available in the range of z2 (z2$Z). z2.sim has the same pattern as z2 but the center is randomly translatated in the availabe z2$Z space and weighted by z2$Z densities. If rand.type = 1, both z1 and z2 are randomly shifted, if rand.type =2, only z2 is randomly shifted.

References

Broennimann, O., M.C. Fitzpatrick, P.B. Pearman, B. Petitpierre, L. Pellissier, N.G. Yoccoz, W. Thuiller, M.J. Fortin, C. Randin, N.E. Zimmermann, C.H. Graham and A. Guisan. 2012. Measuring ecological niche overlap from occurrence and spatial environmental data. Global Ecology and Biogeography, 21, 481-497.

Warren, D.L., R.E. Glor and M. Turelli. 2008. Environmental niche equivalency versus conservatism: quantitative approaches to niche evolution. Evolution, 62, 2868-2883.

See Also

ecospat.grid.clim.dyn, ecospat.niche.equivalency.test