functspec: Calculates the functional specialisation index
Description
Calculates the functional specialisation index for all species in a bipartite network, separately for
the higher and lower trophic level.
Usage
functspec(web, inf.replace = NA)
Arguments
web
A matrix with lower trophic level species as rows, higher trophic level
species as columns and number of interactions as entries.
inf.replace
What should infinite geodesic distances (e.g. between compartments)
be represented as? Defaults to ; only currently implemented alternative is
, which replaces infinite distances by the maximum path length plu
Value
A list with two components, names higher and lower, both containing the functional specialisation index for each species.
encoding
latin1
Details
This index aims to describe the functional specialisation of pollinators and was proposed by Dalgaard et al. (2008). It is a purely qualitative measure.
After calculating the geodesic distances between species, i.e. the minimum number of steps from one species to another, these values are averaged for each species. This mean geodesic distance is interpreted as functional specialisation (Dalgaard et al. 2008).
References
Dalsgaard, B., Mart�n Gonz�lez, A. M., Olesen, J. M., Timmermann, A., Andersen, L. H. and Ollerton, J. (2008) Pollination networks and functional specialization: a test using Lesser Antillean plant-hummingbird assemblages. Oikos117, 789--793