The Rate of Reproduction - Genetic Diversity in Establishing Plant Populations: Founder Number and Geometry - page 150

maintained should be approximately 77%. Strong differences from that
percentage would indicate that other evolutionary forces have been at
work (e.g., localized emigration, strong selection against certain marker-
linked alleles, more inbreeding). Such information could be used to provide
targets for supplementing population expansion as needed if a founded
population is not growing at a suffi ciently high rate and/or appears to be
losing a signifi cant portion of its original genetic diversity.
The populations in Figs. 10.6, 10.7, and 10.8 were all initiated with 10
founders. Do all founding populations under the given conditions require
an r value of approximately 5 to preserve 100% of the founding unique
alleles, regardless of the number of founders? To examine this question,
a series of trials was conducted in which all of the conditions were held
constant as described above, but the effect of changing r was examined for
populations founded by different numbers of founders. The founders were
always placed in an approximate or perfect square with fi ve spaces between
the colonizers, but the squares for trial results depicted in Fig. 10.9 consisted
of either 10 founders (trials a through i), 40 founders (trials A through I), 100
founders (trials K through T), or 400 founders (trials w through z and W
through Z). Given that there are 10 loci, each with 100 different alleles, the
maximum number of unique alleles for these loci that can be present in the
source population is 1,000. But when there are only 10 founders (Fig. 10.9,
populations a through j), there are only 20 draws of alleles from the source
population, and so the theoretical maximum number of alleles is 20 draws
from each of 10 loci = 200 alleles. Since some loci may have the same allele
drawn more than once, the realized number of unique alleles among the
founders is often less than 200, in this case averaging 183 unique founder
alleles for population trials a through j (and given 30 replicate runs per
trial). Likewise, in these trials the mean number of unique alleles present
among the founders for populations A through J, each with 40 founders,
is approximately 555 (the theoretical maximum is 800). When populations
are initiated with 100 founders (trials K through T), this involves 200 draws
from each of the 10 loci, so theoretically, a maximum of 2,000 unique alleles
could be drawn except for the fact that we are limited to a total of 1,000
alleles across the 10 loci. So, in this case duplicate alleles must be drawn
at some loci. Note, however, that even though duplicates of unique alleles
must be drawn for each of the 10 loci, some unique alleles are still not drawn
from the source population by the 100 founders so the realized average total
is approximately 868 across trials K through T, less than the theoretically
possible maximum of 1,000. In drawing 400 founders (trial populations w
through Z), 8,000 alleles are drawn from the source population, and since
for the 10 loci there are only 1,000 unique alleles, many of those must be
drawn two or more times, but each unique allele has a high probability
of being drawn. Indeed, across all of the trials involving 400 founders,