pop.model: Population models

In ibmpm: Individual-based metapopulation model

Description

Population models to use with 'metapop': truncated exponential growth and variants of logistic growth: plain, with extinction at even time intervals, uniform stochastic and gamma stochastic.

Usage

tr.exp.growth(n, r, k, ...)
logistic.growth(n, r, k, ...)
ext.logistic.growth (n, r, k, t, ext.interval = 10L, r.prop = .5, ...)
st.logistic.growth(n, r, k, r.prop = 0.9, ...)
gst.logistic.growth(n, r, k, shape = .01, rate = 1, ...)

Arguments

n	population size (number of reproducing females).
r	maximum number of offspring per female.
k	carrying capacity.
t	time step.
shape, rate	parameters of the gamma distribution.
ext.interval	interval of the extinction (or population crash) events.
r.prop	proportion of r to which the growth rate decreases during the collapse (or minimum of it)
...	other arguments (not used). The user-defined function should always contain the ... argument.

Details

These function are examples of a population model function that can be used with 'metapop' (supplied as 'pop.model' argument).

Value

A vector of per-capita offspring sizes.

Author(s)

Kamil Bartoń

References

REF?

See Also

metapop

Examples

popmods <- c("tr.exp.growth", "logistic.growth", "st.logistic.growth",
			 "gst.logistic.growth", "ext.logistic.growth")

clr <- structure(seq_along(popmods), names = popmods)

RNGkind("Mersenne")
set.seed(17)
l <- 500
k <- 100
r <- 1.05
plot(c(0, l), c(0, k), xlab = "time", ylab = "population size",
	 type = "n", ylim = c(0, k * 1.05), yaxs = "i", axes = FALSE)
axis(1)
axis(2, c(0, k / c(2,1)), labels = c(0, "K/2", "K"), las = 1)
box()
for(pm in popmods) {
	x <- numeric(l)
	x[1] <- 1
	for(i in 2:l) x[i] <- x[i - 1] * get(pm)(x[i - 1], r, k, t = i,
		r.prop = .95, ext.interval = 20, shape = .001, rate = 1)
	lines(1:l, x, col = clr[pm])
}
abline(h = c(0, k), lty= 3)
legend("bottomright", popmods, text.col = clr, cex = .75,
	   title = "Function:", title.adj = 0.1, lty = 1, col = clr,
	   bg = "white")

ibmpm documentation built on May 2, 2019, 5:45 p.m.