volkov {untb} | R Documentation |
Given a community size, biodiversity parameter theta, and an immigration rate m, returns the expected frequency of species with n individuals, for 0<n<=J.
volkov(J, params, bins = FALSE, give = FALSE)
J |
Size of community |
params |
A two-element vector with first element interpreted as
theta, the Fundamental biodiversity parameter and the second, m,
interpreted as the probability of immigration. This argument will
accept the output of optimal.params() |
bins |
Boolean, with default FALSE meaning to return the
expected number of species with 1,2,...J
individuals, and FALSE meaning to return the binned total,
using a Preston-like binning system as used in preston() |
give |
Boolean, with TRUE meaning to return all the
output of integrate() , and default FALSE meaning to
return just the value of the integral |
Returns an object of class “phi”.
The method used is slightly inefficient: the terms to the left ofthe integral sign [in Volkov's equation 7] are integrated and this is, strictly, unnecessary as it is not a function of y. However, taking advantage of this fact results in messy code.
Robin K. S. Hankin
I. Volkov and others 2003. “Neutral theory and relative species abundance in ecology”. Nature, volume 424, number 28.
## Not run: volkov(J=21457,c(theta=47.226, m=0.1)) # Example in figure 1 ## End(Not run) volkov(J=20,params=c(theta=1,m=0.4)) data(butterflies) r <- plot(preston(butterflies,n=9,orig=TRUE)) ## Not run: jj <- optimal.params(butterflies) # needs PARI/GP jj <- c(9.99980936124759, 0.991791987473506) points(r,volkov(no.of.ind(butterflies), jj, bins=TRUE),type="b")