Corridors - Genetic Diversity in Establishing Plant Populations: Founder Number and Geometry - page 275

Founding population number and spatial arrangement:
<Initial_Population>
<Plant age=“0” femaleP=“false” X=“0” Y=“0”/>
<Plant age=“0” femaleP=“true” X=“5” Y=“0”/>....
172 founders placed in a square with 4 grid units between each founder. The
square is placed in the left preserve with closest founders approximately
100 units from the corridor. No founders are placed in the right preserve.
....
<Plant age=“0” femaleP=“false” X=“60” Y=“60”/>
<Plant age=“0” femaleP=“true” X=“65” Y=“60”/>
</Initial_Population>
Source population has an F value of 0:
<FoundersF value=“0.0”/>
As in all previous examples, when two means are said to differ, t test
of means p values are < 0.05 in all analyses in this chapter. Trial C is fi rst
compared ( Fig. 17.1) with trials where there is only one preserve (trial T), and
trials I and U where the 172 founders are split into two groups, one in one
preserve and one in the other. In trial U, the corridor has been removed.
After 12 generations (Fig. 17.1A), the presence of a 20% corridor with
a second preserve (C) yields a population increase of approximately 14.8%
above that where the corridor and second preserve have been removed
(T). Compared to trial C, splitting the 172 founders between preserves (I)
increases population growth by 5.8%, while removing the corridor (U) with
founders split reduces population growth by approximately 5.8% compared
to trial I. Suppose you have two preserves separated by a distance that
is 20% the length of one side of the preserve. Is it benefi cial to have the
corridor when a new population is founded? Note that trials C and U have
populations that grow at approximately the same rate. If the founders are
split between two preserves with no corridor, population growth will be
similar to population growth where founders are placed in one preserve
with a corridor attached to a second preserve.
Considering the founder unique alleles retained by trial populations
(Fig. 17.1B), there is no statistical difference between any of the trials. At the
given expansion rate of even population T, growth is fast enough to prevent
major differences in loss of unique alleles. Differences in heterozygosity (not
shown) amounted to only 1%, with C and T at approximately H = 98%,
and I and U at H = 97%.
The next set of trials (Fig. 17.2) investigated whether the distance of
the placement of the founders from the corridor has any effect. Again, our
reference trial is trial C outlined above, with the 172 founders placed in
a square 100 units to the left of the corridor in the left preserve. Input for