Population Genetics Edge Effects - Genetic Diversity in Establishing Plant Populations: Founder Number and Geometry - page 105

as just described above can be generated with the following shorthand
statement:
<LOCI number_loci=“0” auto_alleles_per_locus=“100” number_automatic_
loci=“30”/>
This shorthand option is useful when all of the different alleles at a locus
have equal frequency. For example, if instead the auto_alleles_per_
locus=“10”, then each of the 10 unique alleles at each of the 30 loci will
have a frequency = 0.1.
Considering the loci panel input described above, the total number
of unique alleles available in the source population is 30 * 100 = 3,000.
However, as in the earlier trials, here we will be selecting 20 founders at
random from that source population. For each locus there are 100 different
alleles, and with 20 founders, there are 40 random draws from that pool
of alleles. Thus, it is possible that, if every allele selected for a particular
locus is unique, a total of 40 unique alleles at such a locus could be present
among the 20 founders. Given that there are 30 loci, the maximum number
of unique alleles that could thus be present among 20 founders is 40 * 30
= 1,200. However, since some of the 20 founding individuals may share at
least one allele in common, it will be seen that the mean number of unique
alleles in founding populations of 20 individuals is less than 1,200.
In the following trial examples, as in the previous trials, the 20 founders
(arranged in two lines parallel to the lowest x-axis with closest spacing of
individuals) will be placed at varying distances from the lower left border
of our preserve.
In Fig. 8.13, for a given letter, lowercase and uppercase letters are
identical trials except that in the former, the source population had 10
loci each with 2 alleles of equal frequency = 0.5, while for the uppercase
letters, the source population had 30 loci each with 100 unique alleles of
equal frequency = 0.01. Founders were placed in different trials at different
distances from the lower left corner of the preserve. Replicate lowercase
and uppercase populations that were identical except in number of alleles
grew at similar rates. Populations at increasing distances from the lower left
corner grew more rapidly because of lower losses of individuals dispersed
outside the preserve. The latter edge effect disappears when founders are
approximately 40 units from the margin since, in that case (letters P and
p), population growth rate was essentially indistinguishable from the case
where founders were placed in the middle of the preserve, 2,560 grid units
away from the borders (letters V and v).
Change in observed heterozygosity through generations for these
populations is shown in Fig. 8.14. Note that there are two sets of
“curves”, one starting at heterozygosity = 0.5 and the other starting with
heterozygosity close to 1. When, per locus, there are only two unique alleles