webFromNicheModel: Generate a web using the niche model.

In TheoreticalEcosystemEcology/alien: Comparative analysis of interaction inference methods

Description

This function is an implementation of the niche model which generates food webs based on 1- a number of species, 2- a niche axis and 3- a value of comnectance.

Arguments

nbsp	An integer giving the number of species considered.
connec	A real positive between 0 and .5 indicating the connectance of the network to be generated.
connect_all	Logical. If TRUE, then all species in the network have a least one prey (but the niche with the lowest niche value).
unbias	Logical. If TRUE, then the first species may not be a basal species.
niche	A vector real positive between 0 and 1 standing for the niche axis. Default is set to NULL, in such case the niche axis is automatically generated.

Details

Three remarks. First, according to Williams and Martinez (2000), the species with the lowest niche value is considered as a basal species and therefore cannot feed upon another species. This introduces a slight bias (e.g the expected connectance is lower than the expected values connec). Second, forcing all the species to be connected introduces another biais (on connectance values) as they tends to be more connected than expected. Third, if one uses its own customed niche axis, values should be between 0 and and 1 and the expected connectance (connec) can vary significantly if the distribution of niche values differ from the uniform distribution used in Williams and Martinez (2000).

Value

A logical matrix describing pairwise interactions. A given line describes the diet of a given species while a column decribes the set of predator associated to a particular species.

Author(s)

Kevin Cazelles

References

Williams, R.J. and Martinez, N.D. (2000) Simple rules yield complex food webs. Nature, 404:180–183.

TheoreticalEcosystemEcology/alien documentation built on Dec. 25, 2021, 5:57 p.m.