Biology Reference
In-Depth Information
where f = the number of focal individuals. The above formulas describe the
situation depicted in
Fig. 9.2
when f = 3 and, for that case, the number of
dispersal grid points available including dispersal to oneself ranges from
15 to 19.
The main point here is not to derive a series of formulas to describe all
of the possible ranges of dispersal points for all possible arrangements and
numbers of dispersing individuals over a realistic range of input dispersal
distances, but rather to demonstrate that ranges of dispersal points can be
calculated and that when a user inputs a given dispersal value, that value
actually implies a realizable range of dispersal distances and available
dispersal points.
Perhaps even more important, the above results provide the fi rst
indication that slight spatial arrangement differences of the same number
of founders in comparative NEWGARDEN trials can affect population
growth. Perhaps this is not so surprising, but are there related effects on
population genetics?
The trend for observed heterozygosity loss being greater near the
preserve edge than among centrally placed founders (Fig. 9.3) was discussed
earlier with regard to genetic edge effects (see Fig. 8.14). Differences in
observed heterozygosity between trials in which the 20 founders are placed
1.00
V
V
l
l
v
LL
v
l
L
v
V
0.95
v
L
l
V
v
L
V
v
l
v
V
L
v
0.90
V
v
v
V
v
L
V
V
v
l
L
v
V
V
v
L
v
V
V
V
V
v
l
L
v
L
v
l
V
V
V
V
V
v
L
v
L
v
l
L
L
l
0.85
L
l
L
l
L
l
L
l
L
l
L
l
l
l
l
l
l
0.80
0
7
14
21
GENERATION
Fig. 9.3
Mean values of observed heterozygosity through time for the four trial populations
for which population growth is depicted in
Fig. 9.1
.
Four NEWGARDEN populations were
generated with identical input conditions (see text) except placement of the 20 founders (always
in two lines of 10 with closest spacing). l, lines of founders begin at the lower left corner of the
preserve running horizontal to the lowest border; L, lines of founders begin at the lower left
corner but run at a 45
o
angle up and into the preserve; founders lines for v and V are identical
to l and L, respectively, except they are placed at the very center of the preserve.
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