The effect of genome duplication on the reproductive ecology of plants

Whole genome duplication, or polyploidy, is the largest genomic alteration observed in nature. Polyploidy occurs in many different taxa, but is a widely tolerated and recurrent evolutionary phenomenon in plants. Although the importance of polyploidy in plants has been touted for approximately 100 years, we have yet to fully understand the ecological consequences of whole genome duplication on plant reproductive biology. Here I investigated how whole genome duplication impacts plant reproductive ecology. Specifically, I studied the effects of whole genome duplication on flowering phenotypes and the contributions of whole genome duplication to three premating barriers. I used a combination of genomic modifications of plants to induce polyploidy in experimental populations, manipulative field experiments to test ecological hypotheses, and literature surveys to examine evolutionary trends. In the first chapter, I used meta-analytical approaches based on published studies to explore the effect of whole genome duplication on several aspects of floral morphology, phenology, and reproductive output in plants. The results suggested that across a wide variety of plant species, morphological traits increase in size (e.g., flower diameter increases), reproductive output decreases, and there were no general trends in the effect of whole genome duplication on flowering phenology. I also observed that variation in reproductive output increases after whole genome duplication, whereas variation does not increase or decrease in phenology or morphology traits. In the second chapter, I build on existing knowledge of the mechanisms involved in premating reproductive isolation of polyploid lineages by investigating the factors that are important in driving assortative mating in the generations immediately following whole genome duplication. I accomplished this by using synthetic polyploids which provide the opportunity to study polyploidy in the generations immediately following formation when reproductive isolation will be critical to establishment. Trifolium pratense, or red clover, was used in an experimental study of diploids and newly formed polyploids to determine if the phenotypic differences caused by whole genome duplication facilitated premating isolation. The premating barriers examined included flowering phenology, self-fertilization rates, flower visitor community, and flower visitor behavior. I found that whole genome duplication increases flower size, but there were no cascading effects that facilitated premating isolation of newly formed polyploids. Together, my results suggest that polyploidy puts plants at a reproductive disadvantage and that if newly formed polyploids are found in sympatry with their diploid progenitors, rapid adaptation is likely necessary to establish and avoid extinction. The effect of genome duplication on the reproductive ecology of plants Laura Porturas B.S. San Diego State University, 2012 Thesis submitted in partial fulfillment of the requirements for the degree of Master of Science in Biology Syracuse University May 2018 Copyright © Laura Porturas, 2018