Date of Award

12-17-2022

Document Type

Thesis

Abstract

Beringia is an extensive geographic region noted for high levels of taxonomic complexity among closely related species. Three such species distributed across Beringia (Claytonia arctica, C. scammaniana, and C. sarmentosa,) exhibit low morphological differentiation between the species, while C. scammaniana includes two additional described morphologies of questionable taxonomic standing, C. "noatakensis" and C. "porsildii". Taxonomic boundaries within this group have been historically disagreed upon and are susceptible to confounding factors such as isolation-by-distance (IBD), discontinuous sampling of continuous variation, and low sequence divergence and morphological differentiation. To assist in species delimitation, multiple approaches combining phylogenomics and spatially explicit population genetics analyses should be used. Genetic material was collected from herbarium specimens at the University of Alaska Museum Herbarium (ALA). Sequence data were extracted and sequenced using the GoFlag target probe set. Phylogenomic analysis and consensus tree reconstruction were performed in ASTRAL. Principal Component Analysis (PCA), Discriminate Analysis of Principal Components (DAPC), and spatial Principal Component Analysis (sPCA) were performed in R ("adegenet" package), and ancestral clustering was calculated in ADMIXTURE. We found clear genetic differentiation between all three species with a close genetic relationship between C. arctica and C. sarmentosa. Neither of the morphotypes "noatakensis" or "porsildii" were genetically differentiable from C. scammaniana, but a strong genetic signal divided the species into northern and southern populations. We conclude that species delineations between C. arctica, C. sarmentosa and C. scammaniana are genetically defensible despite low morphological differentiation. The genetic relationship between C. sarmentosa and C. arctica appears to be closer than previously thought, and further research including the western C. joanneana is needed. The current circumscription of C. scammaniana is correctly inclusive of "noatakensis" and "porsildii", but further research is needed to investigate the genetic divide between northern and southern populations.

Handle

http://hdl.handle.net/11122/13119

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