niche_overlap {tidysdm}

Compute overlap metrics of the two niches

Description

This function computes overlap metrics between two rasters. It currently implements Schoener's D and the inverse I of Hellinger's distance.

Usage

niche_overlap(x, y, method = c("Schoener", "Hellinger"))

Arguments

x

a terra::SpatRaster with a single layer

y

a terra::SpatRaster with a single layer

method

a string (or vector of strings) taking values "Schoener" and "Hellinger"

Details

Note that Hellinger's distance is normalised by dividing by square root of 2 (which is the correct asymptote for Hellinger's D), rather than the incorrect 2 used originally in Warren et al (2008), based on the Erratum for that paper.

Value

a list of overlap metrics, with slots D and I (depending on method)

References

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