Evolutionary dynamics under various modes of reproduction

Thesis (Ph.D.)--University of Washington, 2016-08

Chapter 1. Dispersal and migration are spatially limited in many natural populations. Such limitations can lead to clustering of like types, which weakens competition between unlike types; thus, the rate by which a fitter type displaces an inferior competitor can be affected by the spatial scale of movement. We use a birth-death model to show that, by creating competitive refugia, limited migration can increase the frequency of deleterious mutants at mutation-selection balance. Chapter 2. For a novel genotype to establish in a population, it must (1) be created, and (2) not be subsequently lost. Recombination is a double-edged sword in this process, potentially fostering creation, but also hastening loss as the novel genotype is being recombined with other genotypes, especially when rare. In this chapter, we find that spatial structure may allow a population to harness the creative side of sex while avoiding its destructive side; that is, it may allow a population to create rare genotypes via recombination, and allow those rare genotypes to persist despite recombination. Chapter 3. In this chapter, we show that classical rules for predicting competitive outcomes in continuous-time systems are appropriate for a certain subset of discrete-time systems, which motivates a new discrete-time competitive exclusion principle. However, in discrete-time systems in which our proof's assumptions are not held, we show that classical rules can fail dramatically.