igp {primer}

A Lotka-Volterra Model of Intraguild Predation

Description

A Lotka-Volterra model of intraguild predation, after Holt and Polis (1997). For use with ode in the deSolve package.

Usage

igp(t, y, params)

Arguments

t

the time point for a realization of the integration.

y

the vector of populations, at each time t.

params

a vector or list containing the necessary parameters.

Value

Returns a list of length one which is the vector of the rates of increase (required by ode).

Author(s)

Hank Stevens <[e-mail]>

References

Holt, R.D. and Polis, G.A. (1997) A theoretical framework for intraguild predation. The American Naturalist, 149, 745–764.

Stevens, M.H.H. (2009) A Primer of Ecology with R. Use R! Series. Springer.

See Also

lvcompg, scheffer

Examples

library(deSolve)
params <- c(bpb= 0.032, abp=10^-8, bpn=10^-5, anp=10^-4,  mp=1,
             bnb=0.04, abn=10^-8, mn=1,
             r=1, abb=10^-9.5)
t=seq(0, 60, by=.1)
N.init <- c(B = 10^9, N = 10^4, P = 10^3)
igp.out <- ode(N.init, t, igp, params)
matplot(t, log10(igp.out[,-1]+1), type="l",
          ylab="log(Abundance)")
legend('right', c("B", "N", "P"), lty=1:3, col=1:3, lwd=2,
       bty="n")