# preston

0th

Percentile

##### 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 $1+log2(J)$. 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 required
original
Boolean, with default FALSE meaning to use the nonoverlapping technique discussed below, and TRUE 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

phi

• preston
• Preston
##### 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)
Documentation reproduced from package untb, version 1.7-2, License: GPL

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