time
0
1
2...
t
population size (at time t)
N(0) N(1) N(2) N(t)
growth parameter
λ
λ
λ
N(1) = N(0)
λ
=>
λ
= N(1)/N(0); similarly N(t) = N(0)
λ
t
=>
λ
t
= N(t)/N(0)
This can be converted to an instantaneous growth rate using an exponential: N(t) =
N(0)e
rt
where r is comparable to
λ
. The point is that
different genotypes
could
have
different
λ
's
and hence different fitnesses; selection = the difference between
genotypes in their growth rates.
We can describe the
net reproductive rate
(R
o
) of a genotype or individual in terms
of its
age specific survivorship and fecundity
: x = age, l
x
= probability
of surviving
from age 0 to age x, m
x
= number of offspring produces by an individual of age x.
R
o
=
l
x
m
x
= expected total offspring per female during her lifetime. Now we can
Calculate an l
x
m
x
table, or
life table
.
Age
l
x
m
x
#offspr l
x
'
m
x
'
#offspr'
0
1
0
0
1
0
0
1
0.5
1
0.5
0.5
0
0
2
0.4
This is the end of the preview.
Sign up
to
access the rest of the document.
 Fall '10
 JessicaDigirolamo
 Microbiology, Reproduction, one year, RO, Net reproductive rate, lx mx table, #offspr

Click to edit the document details