Elen Oneal, PhD, is a plant evolutionary geneticist specializing in postzygotic reproductive isolation, genomic imprinting, and speciation in the genus Mimulus. Imprinted expression in the endosperm has been linked to hybrid seed inviability between closely related species in Mimulus, and is thought to evolve as a result of conflict between maternal and paternal genomes over resource allocation to the endosperm, an energy-rich tissue responsible for supporting development of the embryo and germination and survival of the seedling. In collaboration with John Willis at Duke and researchers at North Carolina State University (Miguel Flores-Vergara, Albert Tucci, and Robert Franks), she combines the characterization of hybrid seed failure with genome sequencing of mapping populations and RNA sequencing of endosperm to identify seed lethality QTLs and imprinted genes and relate them to patterns of speciation in Mimulus. She received her BA in Biology from Boston University and her PhD in Evolutionary Biology from the University of Michigan, Ann Arbor, where she worked in the labs of Dr. Lacey Knowles and Dr. Robert Payne studying sexual selection and speciation.
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Genomic imprinting, parent-of-origin effects, and the evolution of postzygotic incompatibility in Mimulus
Elen Oneal, Miguel Flores-Vergara, Albert Tucci, Robert G. Franks, and John Willis
Hybrid seed lethality is a common outcome of hybridization in plants and often exhibits parent-of-origin effects. Interploidy crosses in Arabidopsis, Capsella and other genera have revealed that dosage imbalances in genes critical to normal endosperm development often underlie hybrid seed failure, and moreover, that these genes frequently exhibit differential expression of alleles based on parental origin (genomic imprinting). Seed failure in crosses between diploid plants may similarly result from mis-expression of evolutionarily divergent alleles in the endosperm of hybrid seeds. We used a reciprocal F1 backcross design to isolate parental- and species-specific QTLs associated with hybrid seed failure between species within the Mimulus guttatus species complex, and combined these mapping results with a transcriptomic analysis of M. guttatus endosperm to determine whether genomically imprinted loci may be driving hybrid inviability. Here, we have expanded our approach by characterizing patterns of seed inviability across the M. cardinalis complex and employing the same mapping approach to detect seed inviability QTLs. We report preliminary results from the species pair M. verbenaceous and M. eastwoodiae and compare them to our earlier findings in the M. guttatus complex. Our future work will examine whether the genomic regions that underlie hybrid seed inviability are the same across multiple species pairs in this rapidly diverging complex, or if different genomic regions have caused hybrid inviability to repeatedly evolve between closely related species.