The genomic outcomes of recent and ancient hybridization across a monkeyflower radiation
| dc.contributor.advisor | Streisfeld, Matt | |
| dc.contributor.author | Short, Aidan | |
| dc.date.accessioned | 2025-02-24T19:13:12Z | |
| dc.date.available | 2025-02-24T19:13:12Z | |
| dc.date.issued | 2025-02-24 | |
| dc.description.abstract | New species can form when populations diverge without the homogenizing effects of gene flow. In these cases, genetic and phenotypic differences are able to accumulate, leading to the evolution of reproductive isolation. However, recent genomic analyses have shown that speciation can proceed even with frequent hybridization. This is often due to the effects of natural selection acting against alleles at loci that lead to reduced hybrid fitness. Prior to the evolution of reproductive isolation, hybridization can occur throughout the history of diverging lineages, sometimes facilitating the transfer of beneficial alleles. Thus, by investigating the mechanisms that influence gene flow among hybridizing taxa at various stages of divergence, we can better understand how speciation occurs despite gene flow. In this thesis, I explore the genomic outcomes of hybridization among taxa in the Mimulus aurantiacus species complex, a diverse radiation of wildflowers exhibiting extensive floral and ecological diversity. Leveraging this diversity, I conducted multiple tests for admixture to reconstruct the history of hybridization within this complex. In Chapter 2, I show that ancient hybridization has led to the recurrent evolution of red flowers within the most diverse clade of this radiation. In at least one instance, this ancient hybridization led to strong selection favoring red flowers, which has contributed to the evolution of reproductive isolation. Chapter 3 examines the history of introgression between two hybridizing taxa endemic to the Channel Islands of California, revealing evidence for both recent and ancient hybridization, with stronger selection against recent introgression. Chapter 4 investigates a contemporary hybrid zone between two recently diverged taxa in southern California, finding that selection against gene flow at barrier loci contributes to their differentiation. Collectively, these findings demonstrate how hybridization occurring at different points in time can result in divergence that can fuel diversification or can lead to the maintenance of species barriers. | en_US |
| dc.identifier.uri | https://hdl.handle.net/1794/30449 | |
| dc.language.iso | en_US | |
| dc.publisher | University of Oregon | |
| dc.rights | All Rights Reserved. | |
| dc.subject | adaptive radiation | en_US |
| dc.subject | Genomics | en_US |
| dc.subject | Hybridization | en_US |
| dc.subject | introgression | en_US |
| dc.subject | Mimulus | en_US |
| dc.subject | Speciation | en_US |
| dc.title | The genomic outcomes of recent and ancient hybridization across a monkeyflower radiation | |
| dc.type | Electronic Thesis or Dissertation | |
| thesis.degree.discipline | Department of Biology | |
| thesis.degree.grantor | University of Oregon | |
| thesis.degree.level | doctoral | |
| thesis.degree.name | Ph.D. |
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