preston
Preston diagram of an ecosystem
Gives a standard Preston diagram for an ecosystem.
- Keywords
- math
Usage
preston(x,n=NULL,original=FALSE)
Arguments
- x
- Ecosystem vector that is coerced to class
count
, or a matrix whose rows are species counts - n
- An integer specifying the number of species abundance classes
to use, with default
NULL
meaning to use $1+\log_2(J)$. Must be greater than 1 if specified. Ifx
is a vector,NULL
is not acceptable as the - original
- Boolean, with default
FALSE
meaning to use the nonoverlapping technique discussed below, andTRUE
meaning to use Preston's original formulation.
Details
The Preston diagram is a table showing the number of species having
abundances in specified abundance classes. Consider the following
Preston diagram, created with 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)
).
Value
- Function
preston()
returns an object of class .preston
References
- F. W. Preston 1948.
The Commonness, and Rarity, of Species . Ecology 29(3):254-283 - R. A. Chisholm and M. A. Burgman 2004.
The unified neutral theory of biodiversity and biogeography: comment . Ecology 85(11): 3172-3174 - S. P. Hubbell 2001.
The Unified Neutral Theory of Biodiversity . Princeton University Press
See Also
Examples
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)