DISSERTATION RESEARCH: Patterns of Gene Expression in an Allopolyploid Taxon of Recurrent Origin: A Case Study of the Polypod Ferns

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Polyploidy, or whole genome duplication, is an important evolutionary mechanism, especially in plants. Most notably, it can lead to differential expression of the duplicated genes. Gene expression patterns in allopolyploids (polyploids resulting from hybridization between two or more distinct species) are particularly intriguing because they reveal the consequences of uniting divergent genomes within a single nucleus. Many naturally-formed allopolyploids are known to form recurrently, resulting in species composed of multiple, independently derived lineages. Recurrent origins of allopolyploids were first documented in the ferns, where they appear to be especially common. Do these independent origins yield similar gene expression patterns that are governed by ?rules?, or is the process random? This study will use high-throughput genomic sequencing techniques to compare patterns of gene expression within and among independently derived lineages of the allopolyploid fern Polypodium hesperium. This study aims to better understand the effects of gene duplication, hybridization, and recurrent origins on the phenotypic variation and evolutionary potential of polyploid species. Because many crops are polyploids, an improved understanding of the gene expression changes that accompany polyploidization may provide insight into potential crop improvement. The proposed study will also provide a research training opportunity for a motivated undergraduate.