Spatial Arrangement of Founders - Genetic Diversity in Establishing Plant Populations: Founder Number and Geometry - page 117

9

CHAPTER

Spatial Arrangement of
Founders

In preceding sections we examined the ways in which placement of
founders in the same geometric pattern (two parallel, horizontal lines of 10
founders each) but inset at different distances from a preserve border can
bring about population genetic edge effects. But, given the same number of
founders placed at the same distance from the borders, does the geometric
pattern of introduction matter? For example, what happens if, instead of
two lines of 10, the founders are placed in one long straight line? Or in a
square? Or does it matter if instead of the two described lines placed in the
center of the preserve, fi ve founders are placed in each corner? Or, what
if grid spaces are inserted between and among founders instead of their
being placed with closest average-density grid point spacing? Do such
differences in patterns of introduction have effects on genetic diversity
retention? Is there an optimal geometric pattern solution (or set of optimal
solutions) for introducing founders that maximizes population genetic
diversity retention? How do differing life history characteristics across
species infl uence such considerations? The trials below demonstrate that,
while the effects of founder geometry constitute a complex topic, situations
clearly exist in which the geometry of introduction can have a signifi cant
infl uence on genetic diversity retention in growing populations.
We begin with a simple example: placing the two rows of 10 founders
each, at closest spacing, at the lower left corner of a preserve and running
horizontal to the preserve x-axis border (as was conducted previously)
versus placing the two lines of founders at a 45 o angle, angling up and right
into the preserve (positive slope).
Our initial input data fi le is very similar to the initial basic input trial
used in the previous chapter, but now summarized as follows:
30 loci, each with100 unique alleles of equal frequency = 0.01.
Individuals are bisexual.
An average of two fruit per individual per generation (Poisson
distribution).