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greatest r values losing practically no unique alleles
(Fig. 10.7).
Note that
the input conditions here differed from those for
Figs. 10.1
and
10.2
,
the
resulting rates of loss thus also differing.
10000
j
i
r:
j=18
i=10
h=7
g=5
f=4
e=3.5
d=3
c=2.5
b=2
a=1.5
j
h
i
g
j
h
f
i
g
e
h
f
j
d
1000
e
g
i
c
d
f
h
e
c
b
g
d
j
f
c
b
e
100
i
d
b
h
a
c
g
a
f
b
e
a
d
c
b
a
a
10
c
a
b
d
e
g
h
f
i
j
0
1
2
3
4
5
6
GENERATION
Fig. 10.6
Growth of populations, each initiated with10 annual founders placed in a central
square (other conditions given in the text). Conditions for these populations were identical
except that the reproduction rate, r, varied from 1.5 to 18 as indicated above.
These types of analyses can be used to estimate the population growth
rate needed to preserve all, or most, unique alleles possessed by a given set
of founders for a species with the user-designated life history and genetic
characteristics. Or, if the growth history of a population is known, such
modeling facilitates predictions as to how much of the original genetic
diversity has been retained, and how many supplemental individuals
might be needed to restore the population to approximately the original
levels of diversity.
One of the most important considerations for the conservation of genetic
diversity in establishing populations is that rapid growth in the earliest
generations is critical to maximizing the number of founding unique alleles
retained (e.g., Allendorf and Luikart 2007). But how high must growth rates
be? In analyses of stand expansion, the growth factor for a population may
be defi ned as:
the number of individuals in generation n/the number of founders.
For example, in the populations with conditions as outlined above but
varying in r, a growth factor of at least approximately 5 is required in
the fi rst round of reproduction to preserve approximately 100% of the
founding unique alleles (population g of
Fig. 10.8A)
.
To maintain this
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