Abstract
This dissertation is concerned with the interaction between sexual selection and spatial heterogeneity. I show that the mating system of a species can alter the likelihood of niche expansion when a new environment becomes available. This is true whether or not individuals disperse back into the ancestral habitat, or dispersal moves individuals in one direction only. When mating is error-prone, the conditions for niche expansion are qualitatively altered in that non-infinitesimal increases in fitness are required for niche expansion to proceed. Spatial heterogeneity can bring about the evolution of female choice, even when choice is costly. This brings about positive feedback between female choice and spatial heterogeneity which leads to a correlation between large niche breadth and female choice. When female choice is present, males are expected to attempt to increase their mating success by altering their appearance to females. With spatial variation, this brings about a novel signaling game where males of differing quality signal at the same level. This signaling equilibrium is maintained as long as the advertising signal has on average increasing returns. If female mating strategy is constrained to a best of n mating system, then an equilibrium can exist even when utility is not an increasing function of quality everywhere. Another aspect of sexual selection in hermaphroditic species is the allocation of resources to male and female function. In spatially heterogeneous environments allocation in the more variable sexual function is reduced. The interaction between seemingly unrelated traits is a rich, relatively unexplored area of biology which will can be used to expose the underlying causes of natural patterns.

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© Copyright 2000 Stephen R. Proulx