Award Date

12-15-2025

Degree Type

Thesis

Degree Name

Master of Science (MS)

Department

Life Sciences

First Committee Member

Frank van Breukelen

Second Committee Member

Duane Moser

Third Committee Member

Jef Jaeger

Fourth Committee Member

Michael Schwemm

Fifth Committee Member

Louisa Messenger

Number of Pages

85

Abstract

Spring-fed aquatic ecosystems of the North American Southwest and U.S. Great Basin hosts a plethora of endemic fish species due to the effects of hydrologic fragmentation that resulted from Pleistocene aridification. Threats to endemic fishes worldwide include human intentional or unintentional release of exotic species into their habitats. Early detection of invasive species, while corrective actions are still possible, is critical for management, yet traditional survey methods are often disruptive to sensitive ecosystems, costly, and limited in sensitivity. The recent development of environmental DNA (eDNA) approaches offers powerful alternatives for invasive species monitoring in aquatic systems. In this study, a combination of targeted quantitative PCR (qPCR) and metabarcoding assays were employed to monitor native and invasive species in parallel at the Shoshone Pupfish Refuge in Inyo County, California. This refugium is the sole natural habitat for C. n. shoshone. Currently, mosquitofish have invaded the lower-most pond of the refuge, whereas four upgradient ponds visibly appear to only contain pupfish. eDNA associated with planktonic particulates was sampled by filtration in November 22 and 23, 2024. Two qPCR assays, both based on published primers, were utilized for our demonstration. The first (MiFish) detects a wide range of fish species and was used to verify the presence or absence of fish in the spring source (negative) and 4 the refuge ponds (all positive). The second utilized primers targeting a portion of the mosquitofish mitochondrial cytochrome b gene (Cytb), which showed target detection only in Pond 4. Complementary metabarcoding analysis provided a semi-quantitative comparison of relative species abundance at every site, which confirmed the expectedly pure populations of Pupfish in the upper ponds and invasive mosquitofish (~75%) exclusively in Pond 4. These findings confirm that both qPCR and metabarcoding are reliable tools for targeted detection and community-level biodiversity monitoring within the Shoshone pupfish refuge.

Keywords

Enviromental DNA (eDNA); Mosquitofish (Gambusia Affinis); Shoshone Pupfish (Cyprinidon Nevadensis Shoshone)

Disciplines

Biology | Environmental Sciences | Terrestrial and Aquatic Ecology

File Format

PDF

File Size

2100 KB

Degree Grantor

University of Nevada, Las Vegas

Language

English

Rights

IN COPYRIGHT. For more information about this rights statement, please visit http://rightsstatements.org/vocab/InC/1.0/

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