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Date of Award
Summer 2025
Document Type
Masters Thesis
Department or Program Affiliation
Biology
Degree Name
Master of Science (MS)
Department
Biology
First Advisor
DeChaine, Eric G.
Second Advisor
Williams, Michael P.
Third Advisor
Clark, Douglas H., 1961-
Fourth Advisor
Riedel, Jon L. (Geologist)
Abstract
Ice age refugia have long functioned as hotspots of biodiversity throughout the Pleistocene glaciations, serving as centers of speciation and retainers of relictual and endemic taxa. Numerous ice age refugia in North America have been identified, yet many remain undetected. However, these biologically novel places are at risk due to the projected changes in precipitation and temperature regimes for western North America. This study takes a comparative bryophyte floristics approach to test for an ice age refugium within the vicinity of Barlow Pass, located in the northern Cascade Mountains of Washington State. First, I conducted a geomorphological survey to determine if the Barlow Pass Study Area (BPSA) was ice free during the early through mid-Fraser Glaciation. Second, using herbaria data and conducting field surveys, I developed the bryophyte flora for BPSA, and compared it with bryophyte floras in adjacent areas that were glaciated during the same glacial period. Next, I introduced a novel statistical model (the ‘Relictual Model’) to evaluate putative ice age refugia based on empirical trends of relictual taxa, then tested it on the BPSA. My inventories yielded new records of disjunct arctic and sub-arctic bryophytes that were found within the BPSA while absent from similar sites previously glaciated. The combined geomorphological evidence, regional floristics comparisons and predictions from the Relictual Model suggest that the BPSA functioned as an ice age refugium. This study provides a novel statistical approach to identifying potential refugia and highlights the importance of similar, unstudied areas that remained unglaciated during the last glaciation for maintaining biodiversity.
Type
Text
Keywords
bryophytes, ice age refugia, glaciers, moss, North Cascades, Ice Age, Relicts, refugia, Barlow Pass, Big Four
Publisher
Western Washington University
OCLC Number
1534149790
Subject – LCSH
Bryophytes--North Cascades (B.C. and Wash.); Glaciers--North Cascades (B.C. and Wash.); Glacial epoch--North Cascades (B.C. and Wash.); Relicts (Biology)--North Cascades (B.C. and Wash.); Biodiversity--North Cascades (B.C. and Wash.)
Geographic Coverage
North Cascades (B.C. and Wash.)
Format
application/pdf
Genre/Form
masters theses
Language
English
Rights
Copying of this document in whole or in part is allowable only for scholarly purposes. It is understood, however, that any copying or publication of this document for commercial purposes, or for financial gain, shall not be allowed without the author’s written permission.
Rights Statement
http://rightsstatements.org/vocab/InC/1.0/
Recommended Citation
Berkey, Miles, "The Immensity of Minutiae: Using Bryophytes to Test an Ice Age Refugium Model in the North Cascades" (2025). WWU Graduate School Collection. 1430.
https://cedar.wwu.edu/wwuet/1430