togetherness {bipartite} | R Documentation |
Calculates the number of identical co-presences and co-absences for species-on-islands
Description
Togetherness, or T-score, describes the level of similarity in the distributional pattern of two species. Originally proposed by Stone & Roberts (1992) for biogeographical situations can it also be applied e.g. to pollinators on different host plants.
Usage
togetherness(web, normalise=TRUE, FUN = mean, ...)
Arguments
web |
A matrix with binary or counted interactions/links, where the higher trophic level is represented by columns. |
normalise |
Logical; shall index be normalised to a range of 0-1? |
FUN |
The function to summarise species-pair T-scores with; defaults to mean. |
... |
Arguments passed on to |
Value
Returns the average (default) togetherness of all species combinations.
Author(s)
Carsten F. Dormann
References
Stone, L. and Roberts, A. (1992) Competitive exclusion, or species aggregation? An aid in deciding. Oecologia 91, 419–424
See Also
C.score
for another of Stone & Roberts' indices.
Examples
(m <- matrix(c(0,1,0,0,1,1,0,1,1,0), ncol=2, byrow=TRUE))
togetherness(m)
# or, with two togethernesses:
(n <- matrix(c(0,1,1,0,1,1,0,0,1,1,0,1,0,1), ncol=2, byrow=TRUE))
togetherness(n, normalise=FALSE)
data(Safariland)
togetherness(m)