Calculate mean and variance of life expectancy from a matrix population model
Applies Markov chain approaches to obtain mean and variance of life expectancy from a matrix population model (MPM).
life_expect_mean(matU, start = 1L) life_expect_var(matU, start = 1L) life_expect(matU, start = 1L)
matU |
The survival component of a MPM (i.e. a square projection matrix reflecting survival-related transitions; e.g. progression, stasis, and retrogression). Optionally with named rows and columns indicating the corresponding life stage names. |
start |
The index (or stage name) of the first stage of the life cycle
which the user considers to be the beginning of life. Defaults to 1.
Alternately, a numeric vector giving the starting population vector (in which
case |
Returns life expectancy. If matU is singular (often indicating
infinite life expectancy), returns NA.
Rather than specifying argument start as a single stage class from
which all individuals start life, it may sometimes be desirable to allow for
multiple starting stage classes. For example, if the user wants to start their
calculation of life expectancy from reproductive maturity (i.e. first
reproduction), they should account for the possibility that there may be
multiple stage classes in which an individual could first reproduce.
To specify multiple starting stage classes, specify argument start as
the desired starting population vector (n1), giving the proportion
of individuals starting in each stage class (the length of start
should match the number of columns in the relevant MPM).
See function mature_distrib for calculating the proportion of
individuals achieving reproductive maturity in each stage class.
Roberto Salguero-Gomez <rob.salguero@zoo.ox.ac.uk>
Hal Caswell <hcaswell@whoi.edu>
Caswell, H. 2001. Matrix Population Models: Construction, Analysis, and Interpretation. Sinauer Associates; 2nd edition. ISBN: 978-0878930968
Other life history traits:
entropy_d(),
entropy_k(),
gen_time(),
longevity(),
net_repro_rate(),
repro_maturity,
shape_rep(),
shape_surv()
data(mpm1) # mean life expectancy starting from stage class 2 life_expect_mean(mpm1$matU, start = 2) life_expect_mean(mpm1$matU, start = "small") # equivalent using named life stages # mean life expectancy starting from first reproduction rep_stages <- repro_stages(mpm1$matF) n1 <- mature_distrib(mpm1$matU, start = 2, repro_stages = rep_stages) life_expect_mean(mpm1$matU, start = n1) # variance of life expectancy from stage class 2 life_expect_var(mpm1$matU, start = 1)
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