The Rate of Reproduction - Genetic Diversity in Establishing Plant Populations: Founder Number and Geometry - page 156

Thirty loci, each with 100 different alleles of equal frequency (0.01).
Reproductive rate = 1.5. Pollen rate = 1.0.
Mortality rate = 100% after 1 generation (annuals).
No selfi ng. Random mating value = false (mating is random except for
selfi ng).
Offspring distribution method is Poisson.
Offspring dispersal categories and percentages:
0-6 grid points: 97%.
7-1001 grid points: 3%.
Pollen source distance categories and percentages:
1-10 grid points: 97%.
11-701 grid points: 2.5%.
> 701 grid points: 0.5%.
Population grid and output reporting grid coordinates =
<Rectangle XL=“-2560” YL=“-2560” XH=“2559” YH=“2559”/>
which is a square preserve with 5,120 units on a side, with 26,214,400
establishment grid points.
Both trials have 17 generations, and there are 30 replicate runs per set
of trial conditions.
80 founders colonize each trial. The trials differ only as follows:
Trial S has 80 founders in one square of nine parallel lines of founders, each
line with nine founders (except for one line from which one founder has
been removed). There are 3 grid points between adjacent individuals.
Trial L has 80 founders in four groups of 20 each. In each group, the 20
individuals are divided into two lines that run parallel to the bottom
horizontal border. In each group, there are 9 grid points between adjacent
individuals and between lines. The least distance between the closest
individuals of any two groups is 60 grid units.
Comparisons of population trends for the S versus L populations
demonstrate that founder spatial positioning alone can have several
consequences ( Figs. 10.12 and 10.13) . Placing the founders in subgroups
with greater spacing among individuals greatly enhances population
growth rate. However, observed heterozygosity also drops when such
subgroups are used because increased isolation and consequent inbreeding
produce increase homozygosity in the subgroups, this being refl ected by
the greater values of population subdivision (F values). Note that as the
subdivided populations (trial L) expand and begin to mix, both observed
homozygosity and F values begin to approach the values for the more
contiguous population with founders placed in one square (trial S). The
faster rate of expansion when founders are subdivided also increases the
mean number of unique alleles retained by 7.1% (trial L).