Dioecy - Genetic Diversity in Establishing Plant Populations: Founder Number and Geometry - page 209

14

CHAPTER

Dioecy

All of the previous analyses involved species in which individuals were
bisexual. Individuals in the examples in this section are of one or the
other sex (dioecious), either bearing ovule and offspring (“females”) or
producing microgametes (“males”). Except for the life history trait of
dioecy, these sample trials are very similar in life history details to earlier
sample trials:

The source population has 30 loci, each with 100 different alleles of equal
frequency = 0.01. A total of 3,000 unique alleles are thus available across
these loci.
The species is a dioecious annual.
Reproduction rate: In previous examples, reproduction rate was generally
held constant while variation in other life history characteristics was
examined. In the trials discussed below, one question of interest is, how do
dioecious populations compare to bisexual populations under otherwise
identical NEWGARDEN input parameters? To make comparisons between
such populations, r must be two times as large for dioecious populations as
for the contrasting bisexual population. Note that r describes the offspring
output per reproducing individual. Since a dioecious population will have
only half the reproducers of a bisexual population, the value of r for a
dioecious population must be doubled for analyses to be comparable.
Seed reproduction across reproducers is allocated according to the Poisson
distribution. When a population is designated as being dioecious, the sex
of the offspring is selected at random, with each alternative being equally
likely.
Selfi ng rate is 0 with Random Mating value = false: these conditions always
hold under dioecy.
Offspring = microgamete dispersal distances (unless noted), with trials
having average species density grid point unit dispersal distances of
either:
10 (offspring and microgamete dispersal within or from the nearest
441 grid points) or
20 grid units (offspring and microgamete dispersal within or from the
nearest 1,681 grid points).