||<p>Bryophytes, by their haploid dominant life cycle, possess several unique qualities
ideal for study of mating patterns. In particular, the possibility of intragametophytic
selfing in some species, and the vegetative propagation of gametes allow for a unique
window into the haploid stage that is intractable in other groups. Despite these advantages,
there have been relatively few studies on mating patterns bryophytes in natural populations.
<italic>Sphagnum</italic> (peatmoss) is an excellent case study in the interactions
between sexual condition, ecology, and mating patterns. In the first Chapter, we use
microsatellites to characterize the genetic diversity and mating patterns in fourteen
species of <italic>Sphagnum</italic>, diverse in sexual condition (separate vs combined
sexes in the haploid stage) and ecology (microhabitat variance along the water table).
We find that genetic diversity and mating patterns are related only in species with
separate sexes, that sexual condition and ecology have interacting effects on inbreeding
coefficients, and that inbreeding depression is not a common phenomenon in <italic>Sphagnum</italic>.
In the second Chapter, we conduct an intensive survey of one population of <italic>Sphagnum</italic>
macrophyllum, to detect whether variance in haploid fecundity and mating success is
related to diploid fitness. We find a relationship between mating success and fecundity
(a signal of sexual selection), and fitness of the diploid generation is connected
to the parentage of the haploid generation. Finally, in Chapter 3 we use phylogenetic
comparative methods to track the phylogenetic signal in microhabitat preference in
<italic>Sphagnum</italic>. We find extremely fast rates of evolution along the micronutrient
gradient, but high phylogenetic signal along a hydrological gradient. Given that <italic>Sphagnum</italic>
species living high above the water table have reduced water availability, phylogenetic
signal in the hydrological gradient has macroevolutionary implications for mating
systems in <italic>Sphagnum</italic>.</p>