Dissertation Research: The evolution of self-incompatibility loci in the invasive ascidian genus, Ciona

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Studies of animal fertilization proteins have focused on species with separate sexes, in which self-fertilization, or selfing, cannot occur. In hermaphrodites it is unclear how an animal avoids fertilizing its own eggs with its own sperm, in other words, how it achieves self-incompatibility. The goal of this proposal is to characterize the evolutionary forces that govern genetic variation in self-incompatibility genes in the invasive ascidian, Ciona intestinalis. Understanding self-incompatibility has profound implications for understanding mate recognition in general. The self-incompatibility (SI) loci in C. intestinalis are the first definitive SI loci to be characterized in animals. This research will be among the first to elucidate how animals have responded to the challenges of avoiding inbreeding, and balancing fitness from male and female gametes. This research will also build upon an extensive body of work on the role of mate availability as an evolutionary force in marine systems. Invasive species cost the U.S. about $120 billion/year and have devastating effects on ecosystem diversity. Ciona contributes to these costs by contaminating aquaculture projects, fouling boats, and outcompeting native species. Evidence from invasive plants suggests that changes in the prevalence of selfing may facilitate invasion success. Identification of selfing genotypes could reveal populations with greater potential for invasion and range expansion.