preston | R Documentation |
Gives a standard Preston diagram for an ecosystem.
preston(x,n=NULL,original=FALSE)
x |
Ecosystem vector that is coerced to class |
n |
An integer specifying the number of species abundance classes
to use, with default |
original |
Boolean, with default |
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 abundance 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)
).
Function preston()
returns an object of class “preston
”.
Robin K. S. Hankin
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(untb(start=rep(1,100), prob=0.01, gens=1000, keep=FALSE))
data(butterflies)
preston(butterflies)
preston(butterflies,original=TRUE)
data(copepod)
preston(copepod)
plot(preston(copepod))
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