Simulation of presenceabsence matrices (nonclustered)
Description
Generates a simulated matrix where the rows are interpreted as regions
and the columns as species, 1 means that a species is present in the
region and 0 means that the species is absent. Species are generated
i.i.d.. Spatial autocorrelation of a species' presences is governed by
the parameter p.nb
and a list of neighbors for each region.
Usage
1 2 3 4 
Arguments
neighbors 
A list with a component for every region. The
components are vectors of integers indicating
neighboring regions. A region without neighbors (e.g., an island)
should be assigned a list 
p.nb 
numerical between 0 and 1. The probability that a new
region is drawn from the nonneighborhood of the previous regions
belonging to a species under generation. Note that for a given
presenceabsence matrix, this parameter can be estimated by

n.species 
integer. Number of species. 
n.regions 
integer. Number of regions. 
vector.species 
vector of integers. If

species.fixed 
logical. See 
pdf.regions 
numerical vector of length 
count 
logical. If 
pdfnb 
logical. If 
Details
The principle is that a single species with given size is generated
onebyone region. The first region is drawn according to
pdf.regions
. For all following regions, a neighbor or
nonneighbor of the previous configuration is added (if possible),
as explained in pdf.regions
, p.nb
.
Value
A 01matrix, rows are regions, columns are species.
Author(s)
Christian Hennig chrish@stats.ucl.ac.uk http://www.homepages.ucl.ac.uk/~ucakche
References
Hennig, C. and Hausdorf, B. (2004) Distancebased parametric bootstrap tests for clustering of species ranges. Computational Statistics and Data Analysis 45, 875896. http://stat.ethz.ch/ResearchReports/110.html.
Hausdorf, B. and Hennig, C. (2003) Biotic Element Analysis in Biogeography. Systematic Biology 52, 717723.
Hausdorf, B. and Hennig, C. (2003) Nestedness of nerthwest European land snail ranges as a consequence of differential immigration from Pleistocene glacial refuges. Oecologia 135, 102109.
See Also
autoconst
estimates p.nb
from matrices of class
prab
. These are generated by prabinit
.
prabtest
uses randpop.nb
as a null model for
tests of clustering. An alternative model is given by
cluspop.nb
.
Examples
1 2 3 