preston(x,n=NULL,original=FALSE)
count
, or a
matrix whose rows are species countsNULL
meaning to use
$1+log2(J)$. Must be greater than 1 if specified.
If x
is a vector, NULL
is not acceptable as the
program does not try to guess what is requiredFALSE
meaning to use the
nonoverlapping technique discussed below, and TRUE
meaning to use Preston's original formulation.preston()
returns an object of class preston
.
original = FALSE
:
1 2 3-4 5-8 9-16 17-32 33-64 65-Inf number of species 10 5 7 5 1 5 4 0
This shows that there are 10 species with abundance 1 (that is, singletons); 5 species with abundance 2; 7 species with abudance 3-4; 5 species with abundance 5-8, and so on. This method is used by Hubbell (2001), and Chisholm and Burgman (2004).
Setting argument original
to TRUE
means to follow Preston
(1948) and count any species with an abundance on the boundary between
two adjacent abundance classes as being split 50-50 between the classes.
Thus the fourth class would be
$phi_4/2+phi_5+phi_6+phi_7+phi_8/2$
where $phi_i$ is the number of species with abundance
$i$ (given by phi(x)
).
phi
preston(untb(start=rep(1,100), prob=0.01, gens=1000, keep=FALSE))
data(butterflies)
preston(butterflies)
preston(butterflies,original=TRUE)
data(copepod)
preston(copepod)
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