Date of Award
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Master of Science (MS) in Biology
Establishing genetically diverse communities that can adapt to dynamic selective pressures is crucial in ecological restoration. However, the genetic structure of native plant species used for restoration is often poorly understood. Pseudoroegneria spicata, is a keystone species of the Inland Northwestern US that has become a staple in commercially available restoration seed mixes. It is abundant in remnant prairies of the endangered Palouse Prairie ecoregion, which is characterized by rolling hills of deep loess soil. Less than 1% of native Palouse Prairie is left, due to agricultural conversion, with remnants highly fragmented and isolated. P. spicata is also common in nearby Channeled Scabland habitats formed by flooding during the last glacial advance and characterized by relatively shallow soils. Previous studies of the genetic structure of P. spicata have not included populations from the Northern Palouse and Channeled Scablands. My goal was to assess the genetic structure of P. spicata across Palouse Prairie remnants and Channeled Scabland habitats in Eastern Washington, and determine relatedness to commercial seed. I hypothesized that habitat differences between the Palouse and Channeled Scablands would lead to genetic differentiation between P. spicata populations. I also expected that local source-identified commercial plant iv material would be more closely related to plants from our sampling locations than plant material collected from a larger nearby area and pooled. Plant DNA samples were collected from six locations in the Channeled Scablands and Palouse Prairie and two commercial sources. I calculated inbreeding coefficient, conducted principal component analyses, and used Bayesian cluster analysis to test for inbreeding, differentiation of populations, and relatedness of native propagule sources. Pseudoroegneria spicata differentiated along a north-south latitudinal gradient instead of between different habitat types. Commercially sourced seeds from a certified source-identified provenance were more closely related to northern sites, while seeds sourced from the larger region were more similar to southern sites. There were no signs of inbreeding in commercial seed sources, however I found possible evidence of hybridization at a native seed nursery. Samples from one of the larger Palouse remnants had a lower inbreeding coefficient than the rest of the sites, highlighting the importance of its continued preservation.
Bean, Ethan Timothy, "Genetic structure of Pseudoroegneria spicata in the Northern Palouse Prairie and Channeled Scablands" (2021). EWU Masters Thesis Collection. 659.