Some of the material in is restricted to members of the community. By logging in, you may be able to gain additional access to certain collections or items. If you have questions about access or logging in, please use the form on the Contact Page.
Genetic variation is a dominant feature in the study of evolution. The presence of variation is embedded at every level, from a single individual all the way to different species. Understanding the mechanisms that allow variation to be introduced and maintained is crucial to our understanding of nature. If empirical data and observations provide the substrate needed for such understanding, the role of theory is instead to train our intuition and help experimenters in formulating testable hypotheses. Here I use mathematical modeling as a tool to investigate the effects of genetic variation at different levels. I begin by looking at variation expressed at the level of an individual. Enzyme isoforms are a pervasive presence in many species. They can be produced by different genes, different alleles or by alternative splicing of a single gene. I examine the potential benefit provided by the presence of enzyme isoforms in the Drosophila circadian rhythm. I show that controlling isoform proportion can be a powerful mechanism to reduce the effects of variations in the values of system parameters, thereby increasing system robustness. My second research project looked at genetic variation at the population level. Gamete recognition proteins are central to reproduction. They determine gametic compatibility both within and between species. In marine broadcast spawners an astonishing number of variants have been found for these proteins. The mechanism responsible for this variation is thought to be sexual conflict. This conflict arises because each sex has different and opposing interests at fertilization. I investigate how sexual conflict and spawning behavior can drive the evolution of recognition protein polymorphism and promote gametic disequilibrium by assortative mating. I conclude by looking at variation at the species level. Marine broadcast spawners need to synchronize the release of their gametes to increase the chance of successful fertilization. Highly synchronized gamete release can result in polyspermy. Polyspermy is the fusion of multiple sperm with a single egg at fertilization, making an unviable zygote. A possible strategy to avoid polyspermy is to shift spawning time. I show how a population where spawning time is the phenotype under selection can split in two reproductively isolated populations in sympatry.
A Dissertation Submitted to the Department of Biological Science in Partial Fulfillment of the Requirements for the Degree of Doctor of Philosophy.
Includes bibliographical references.
Florida State University
Use and Reproduction
This Item is protected by copyright and/or related rights. You are free to use this Item in any way that is permitted by the copyright and related rights legislation that applies to your use. For other uses you need to obtain permission from the rights-holder(s). The copyright in theses and dissertations completed at Florida State University is held by the students who author them.