Browsing by Subject "seed sourcing"

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    Human Impacts on Minnesota Prairie Genetics: Salted Environments, Echinacea Hybrids, and Local Seed Sourcing
    (2018-12) Goldsmith, Nicholas
    Humans are modifying various aspects of the environment, from building roadways, to moving species beyond their range, to purposefully reconstructing plant communities. These actions affect both the current distribution of populations and the potential for populations to persist. In this dissertation, I examine two human-caused impacts to plant populations and one aspect of efforts to support native plant communities. In chapter one, I focus on the impact of sodium chloride, a road de-icing agent. Such agents can damage plants and change dominant species along roadsides. I carried out two experiments, planting a pedigreed population of the native prairie legume Chamaecrista fasciculata into a roadside environment and into four greenhouse salinity treatments. I tracked their survival and reproduction. Using Aster models, I detected potential to adapt both to roadside salinity and to low salinity in the greenhouse. I also detected gene-by-environment interactions in both experiments. These results indicate a potential to adapt, but a potential which may be slowed by gene-by-environment interactions. In chapter two, I focus on the interaction of Echinacea pallida, introduced outside of its range, on local populations of E. angustifolia. I used controlled crosses and monitored their seed set and the survival of the progeny over five years. Crossing of the two species produces offspring capable of surviving multiple years. Comparing conspecific and heterospecific crosses, I found that conspecific crosses of E. angustifolia resulted in lower pollen compatibility and survival to year four than did conspecific crosses with E. pallida or heterospecific crosses. These results demonstrate a risk to E. angustifolia populations by E. pallida populations planted nearby. In chapter three, I focus on efforts to remediate human impacts through restoration of Minnesota prairie plant communities, which depends on the production and use of source-identified seeds. Restoration practice often emphasizes use of seeds sourced from populations near the restoration site, but demand frequently outstrips supply. I conducted focus group interviews with groups of producers and users of locally-sourced seeds to identify strengths and weaknesses with current practices. Participants discussed continued increases in production and use of these plant materials but also identified aspects where improvement is needed.
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    Seed sourcing for ecological restoration in an era of climate change: Impacts of source latitude and hybridization
    (2022-11) Rushing, Naomi
    In Minnesota, tallgrass prairie ecosystems currently occupy less than 1% of their former range. The importance of maintaining and restoring this dwindling ecosystem is well recognized but the ecological restoration process is complex, particularly in the current era of climate change. Successful establishment and persistence of restoration populations depends in large part on seed source selection. Previous research and discussion have explored the importance of maintaining local adaptation and genetic diversity. There has also been discussion of intentionally translocating populations in specific directions in response to ongoing climate change. In an effort to inform seed sourcing guidelines, the research presented here investigates (1) the implications for restoration of translocating populations across latitudes, (2) the phenological and fitness outcomes of hybridization between distinct populations, and (3) genetic effects contributing to differences between divergent populations. Chapter 1 focuses on the phenological and fitness impacts of translocation along a latitudinal gradient within the state of Minnesota using a common garden style approach and three perennial prairie species. Chapters 2 and 3 expand upon this work and investigates the impact of translocation on an annual prairie species sampled across a latitudinal span from Minnesota to Missouri, as well as investigating the outcome of hybridization between these divergent populations. Our results highlight the importance of latitude of origin to both phenology and fitness of translocated populations, as plants from more northern locations tended to have earlier timing of flowering and fruiting in the common gardens, as well as higher fitness for all of our study species. In addition, Chapters 2 and 3 demonstrate the potential positive impacts of hybridization across a range of geographic distances with no indication of outbreeding depression, as hybrid generations tended to have higher mean fitness in the common gardens than the parental generations. However, phenological mismatch between seed source and planting site in populations translocated across large latitudinal distances can result in low fitness and limit hybridization with local populations. Taken together, these results highlight the benefits of hybridization between populations, while demonstrating the potential drawbacks of translocating populations across large latitudinal distances.