| pop.projection {popbio} | R Documentation |
Calculates the population growth rate and stable stage distribution by repeated projections of the equation n(t+1)=An(t).
pop.projection(A,n,iterations=20)
A |
A projection matrix |
n |
An initial age or stage vector |
iterations |
Number of iterations |
Eventually, structured populations will convergence to a stable stage distribution where each new stage vector is changing by the same proportion (lambda).
A list with 5 items
lambda |
Estimate of lambda using change between the last two population counts |
stable.stage |
Estimate of stable stage distribution using proportions in last stage vector |
stage.vector |
A matrix with the number of projected individuals in each stage class |
pop.sizes |
Total number of projected individuals |
pop.changes |
Proportional change in population size |
Chris Stubben
see section 2.2 in Caswell 2001
stage.vector.plot to plot stage vectors
stages<-c("seedling", "vegetative", "flowering")
A<-matrix(c(
0, 0, 6,
0.4, 0.6, 0.02,
0.01, 0.2, 0.25
), nrow=3, byrow=TRUE,
dimnames=list(stages,stages)
)
n<-c(25,25,25)
pop.projection(A,n, 15)
eigen.analysis(A)$damping.ratio
pop.projection(A,n, 50)$pop.changes
data(whale)
A<-whale$T+whale$F
n<-c(4,38,36,22)
## convergence is slow with damping ratio close to 1
pop.projection(A,n, 10)
eigen.analysis(A)$damping.ratio
pop.projection(A,n, 250)$pop.changes