Date of Award

Summer 2017

Document Type


Degree Name

Master of Science (MS) in Biology




Invasive species pose a serious threat to native ecosystems. In eastern Washington brook stickleback (Culaea inconstans) is an important invasive species, especially at Turnbull National Wildlife Refuge, where they compete with waterfowl for food resources and are associated with declines in habitat quality. Understanding the invasion routes of this invasive species may help managers implement strategies to prevent further spread and mitigate damages caused by these fish. The objectives of this study were to identify the most likely point of brook stickleback invasion, to determine their most likely invasion routes, and to investigate landscape features and processes that may be impacting gene flow between populations. Genotypes at nine microsatellite loci from 560 brook stickleback from 20 putative populations were used determine the genetic variation within and among populations. Genetic diversity was highest in the headwaters of Pine Creek (HE = 0.753 in Kelley Creek, AR = 4.466 in Pine Creek) and on average water bodies in Pine Creek had greater genetic diversity than elsewhere (HE, p = 0.016; AR, p = 0.02). FIS values were globally high and Hardy-Weinberg expectations were violated due to an excess of homozygotes. A concrete dam at Cheever Lake and watershed boundaries act as barriers to gene flow as geographically proximate sites have on either side of these barriers higher than expected genetic distance. The data presented here along with the historically documented distribution of brook stickleback in eastern Washington indicate that the most likely point of invasion was in the headwaters of Pine Creek and that brook stickleback subsequently moved down Pine Creek to the confluence with Rock Creek and from there dispersed both upstream and downstream.

Creative Commons License

Creative Commons Attribution-Noncommercial-No Derivative Works 4.0 License
This work is licensed under a Creative Commons Attribution-Noncommercial-No Derivative Works 4.0 License.

Included in

Biology Commons