Theses and Dissertations

Date of Award


Document Type


Degree Name

Master of Science (MS)


Agricultural, Environmental, and Sustainability Sciences

First Advisor

Dr. Richard J. Kline

Second Advisor

Dr. Md. Saydur Rahman

Third Advisor

Dr. Drew R. Davis


Environmental DNA (eDNA) assays have become a major aspect of amphibian surveys in the past decade. These methods are highly sensitive, making them well-suited for monitoring rare and cryptic species. Current efforts to study the Rio Grande Siren in south Texas have been hampered due to the cryptic nature of these aquatic salamanders. Arid conditions further add to the difficulty in studying this species, as many water bodies they inhabit are ephemeral, sometimes constraining sampling efforts to a short window after heavy rain. Additionally, sirens are known to cease activity and reside underground when ponds begin to dry or as water temperatures increase. Conventional sampling efforts require extensive trap-hours to be effective, which is not always possible within the required sampling window. This study presents the development of a novel eDNA assay technique for this elusive species and compare eDNA results with simultaneous trapping at multiple sites to assess the relative effectiveness of the procedure. This methodology gives promise for future work assessing the distribution and status of the Rio Grande Siren and has potential for use on other south Texas amphibians. An expansive literature review on the subject of eDNA metabarcoding is also presented, along with a plan for implementation of this method in south Texas for community amphibian studies.


Copyright 2020 Krista M. Ruppert. All Rights Reserved.