levins {primer}R Documentation

Classic metapopulation model

Description

A function for the classic metaapopulation dynamics, for use with ode in the deSolve package.

Usage

levins(t, y, parms)

Arguments

t Argument for time
y A scalar for the population variable
parms Vector or list of parameters

Value

Returns a list of length one, for use with ode in the deSolve package.

Component 1 vector of the state variable (a scalar for the proportion of sites occupied).

Author(s)

Hank Stevens <HStevens@muohio.edu>

References

R. Levins. Some demographic and genetic consequences of environmental heterogeneity for biological control. Bulletin of the Entomological Society of America, 15:237–240, 1969.

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

See Also

gotelli, hanski,lande, MetaSim clogistic

Examples

##---- Should be DIRECTLY executable !! ----
##-- ==>  Define data, use random,
##--    or do  help(data=index)  for the standard data sets.

## The function is currently defined as
function (t, y, parms) 
{
    p <- y[1]
    with(as.list(parms), {
        dp <- ci * p * (1 - p) - e * p
        return(list(dp))
    })
  }
library(deSolve)
p <- c(ci=.1, e=.01)
time <- 1:10
initialN <- .3
out <- ode(y=initialN, times=time, func=levins, parms=p) 
plot(time, out[,-1], type='l')

[Package primer version 0.1 Index]