| This thesis provides data supporting an integrated understanding of how the mechanisms of mating system, mate choice, and dispersal interact in complementary ways to ensure population persistence of species. While this research has focused on kelp, results here are applicable to the ecology and evolution of many organisms with complex life history strategies, include marine invertebrates, other algae and terrestrial plants.;Using microsatellite markers developed for this project, I revealed uncharacteristic genetic population structure of a colonizing intertidal alga, Alaria nana, at two scales. Data suggest low rates of dispersal between populations, an unexpected result considering this species' capacity to colonize newly disturbed patches in the intertidal. At a small scale, comparisons to another genetically structured annual, Postelsia palmaeformis, uncover greater genetic diversity within patches, suggesting relative increased dispersal. Genetic structure at the geographic range scale of Alaria nana demonstrates restricted movement between distantly settled populations conforming to an island model of migration.;To understand the effects of species longevity on reproductive strategy, I compare the reproductive outcome and fitness effects of selfing and asexual reproduction between annual and perennial representatives of kelp. Evidence supports the theory of reproductive assurance, where annual species with non-overlapping generations are more apt to successfully self and reproduce asexually.;Species of differing longevity may also differ in dispersal patterns, given separate challenges of sibling competition, probability of finding suitable habitat and mates, and avoidance of self in the face of inbreeding depression. I compare the spore dispersal potential of a representative annual and a long-lived perennial. I show that the annual concentrates spores closer to the point of release.;Lastly, I attempt to explain patterns of spore settlement and mate choice as a factor in selfing success between the annual, Alaria nana, and Lessoniopsis littoralis, a long-lived perennial known to suffer severe negative effects of inbreeding. Results suggest that mate choice is not occurring, and that perhaps post-zygotic mechanisms are responsible for differences between the number of offspring produced via selfing and outcrossing in ephemeral and long-lived kelp. |
