Browsing by Author "Oyler-McCance, Sara, committee member"

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Open Access
Genetic analysis reveals bidirectional fish movement across the Continental Divide via an interbasin water transfer
(Colorado State University. Libraries, 2021) Harris, Audrey Catherine, author; Kanno, Yoichiro, advisor; Winkelman, Dana, advisor; Oyler-McCance, Sara, committee member; Morrison, Ryan, committee member
Interbasin water transfers are becoming an increasingly common tool to satisfy municipal and agricultural water demand, but their impacts on the movement and gene flow of aquatic organisms are poorly understood. The Grand Ditch is an interbasin water transfer that diverts water from tributaries of the upper Colorado River on the west side of the Continental Divide to the upper Cache la Poudre River on the east side of the Continental Divide. I used single nucleotide polymorphisms to characterize population genetic structure in cutthroat trout (Oncorhynchus clarkii) and determine if fish utilize the Grand Ditch as a movement corridor. Samples were collected from two sites on the west side and three sites on the east side of the Continental Divide. I identified two genetic clusters, but they did not align with the west and east sides of the Continental Divide. Spatial distributions of admixed individuals indicated that the Grand Ditch facilitated bidirectional fish movement across the Continental Divide, a major biogeographic barrier. Many others have demonstrated the ecological impacts of interbasin water transfers, but this study is one of the first to utilize genetics to understand how interbasin water transfers affect connectivity between previously isolated watersheds. I also discuss implications on native trout management and the need for balancing water demand and biodiversity conservation.
Embargo
Riverscape features and isolation-by-distance shape spatial genetic structure of Brook Trout in a Colorado headwater stream network
(Colorado State University. Libraries, 2024) Stack, Taylor, author; Kanno, Yoichiro, advisor; Winkelman, Dana, advisor; Oyler-McCance, Sara, committee member; Fairchild, Matthew, committee member; Funk, William Chris, committee member
Understanding the influences of riverscape characteristics on gene flow in stream networks is crucial for managing population connectivity in freshwater species. In this study, we examined the fine-scale genetic structure of non-native Brook Trout (Salvelinus fontinalis) in a headwater stream network proposed for future reintroduction of native trout. Using 12 microsatellite loci, we genotyped 757 individual Brook Trout from 22 sampling sites throughout the dendritic stream network and modelled the effects of physical riverscape features on gene flow. Genetic clustering analysis identified four distinct tributary groups, indicating fine-scale population structure, while pairwise genetic differentiation estimates (mean FST = 0.04; mean Jost's D = 0.06) revealed some genetic connectivity across the network. Riverscape genetics models identified vertical barriers and steep stream gradients as key factors impeding gene flow, whereas higher order mainstem streams were more conducive to trout movement. Gene flow was stronger in the downstream direction, and models with interaction terms revealed that asymmetries between upstream and downstream gene flow were more pronounced in stream reaches with barriers and steep gradients. Mantel tests confirmed that both waterway distance between sites and riverscape resistance significantly influence genetic connectivity across the network. Overall, this study demonstrates that spatial genetic patterns in stream networks are shaped by a combination of isolation-by-distance, riverscape resistance, and asymmetric stream flow. Our findings suggest that this reintroduction area provides sufficient genetic connectivity to support a metapopulation of native trout.