Browsing by Author "Etterson, Julie R"

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    Genetic survey of Minnesota Euphrasia species, 2019-2022
    (2023-08-17) Gross, Briana L; Etterson, Julie R; Vallez, John P; Carlson, Ryan; blgross@d.umn.edu; Gross, Briana L; University of Minnesota - Duluth Department of Biology; University of Minnesota - Duluth Department of Biology
    This study represents a genetic survey of native and invasive Euphrasia populations in Minnesota, with the objective of understanding the degree of hybridization among species and the threat posed to the native species. Euphrasia hudsoniana is an arctic relict species that persists along the north shore of Lake Superior. A previous genetic study revealed hybridization between the invasive and the native species at two locations. In this study, we expanded our sampling to include nearly all known populations of E. hudsoniana as well as populations of invasive Euprhasia and suspected hybrid zones. Populations of invasive Euphrasia included those found close to E. hudsoniana as well as populations with taxonomically verified specimens from the University of Minnesota Herbarium and the Olga Lakela Herbarium. Based on these records, we included populations of E. stricta, E. nemorosa, E. micrantha, and a variety of hybrids among them. We generated RAD-seq data for a total of 667 samples. Gene flow from the invasive into the native was substantial at some locations, indicating that the native species is threatened with genetic swamping. There was also evidence of gene flow among some of the invasive lineages. There were three main invasive lineages identified based on genetic groupings, but these did not always correspond to the taxonomic assignment of the species according to herbarium specimens.
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    Resurrecting Urban Sunflowers: Phenotypic and Molecular Changes between Antecedent and Modern Populations Separated by 36 Years
    (2023-08-07) Spear, Marissa M; Levi, Sophie J; Etterson, Julie R; Gross, Briana L; blgross@d.umn.edu; Gross, Briana L; University of Minnesota - Duluth Department of Biology
    Resurrection experiments provide a unique opportunity to evaluate phenotypic and molecular evolution in response to environmental challenges. To understand evolution of urban populations of Helianthus annuus, we compared plants from 36-year-old antecedent seed collections to modern seed collections from the same area using molecular and quantitative genetic approaches. We found 200 differentially expressed transcripts between antecedent and modern groups, and transcript expression was generally higher in modern samples as compared to antecedent samples. Admixture analysis indicated gene flow from domesticated to modern populations over time. After a greenhouse refresher generation, one antecedent-modern population pair was grown under two water availability (well-watered and drought) and temperature (ambient and elevated by 2.8°C) conditions reflecting historical and contemporary climates. Overall, 78% (7 out of 9) of traits differed between the antecedent and modern populations, with modern individuals displaying some trait changes that are coherent with climate changes expectations and some trait changes in the direction of crop varieties. Phenotypic selection analysis showed that modern trait values were often favored by selection, especially in environmental treatments resembling modern conditions. Trait heritability in the antecedent population was twice as high as in the modern population, on average. In addition, phenotypic plasticity for some traits, such as flowering phenology, was present in the antecedent population but absent in the modern population. The combination of phenotypic and molecular information suggests that evolution has been influenced by crop-wild introgression, adaptive processes, and drift. We discuss these results in the context of continued evolution in response to anthropogenic factors.
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    Sunflower Evolution and Adaption to Climate Change
    (2021-04-30) Levi, Sophie J; Spear, Marissa M; Etterson, Julie R; Gross, Briana L
    Temperatures in Minnesota will rise drastically in the next several decades, and it is important to understand how plants will react to this climate change. Some researchers have studied these reactions with resurrection studies, in which modern and antecedent plant lines are grown in a common environment to monitor evolution thus far and possible adaption to new environments. However, few studies have investigated the hybrid progeny of these resurrected lines. The hybrids serve as a study system for understanding evolution and maternal effects. We investigated these hybrid progeny from a resurrection study of Helianthus annuus and found surprising phenotypic plasticity, decreased transgenerational plasticity in warmer temperatures, and introgression from cultivated varieties.