Date of Award

Summer 2025

Document Type

Thesis

Degree Name

Master of Science (MS)

Department

Biological Sciences

Program/Concentration

Biology

Committee Director

John P. Whiteman

Committee Member

Ian Bartol

Committee Member

Taylor Sloey

Abstract

Obtaining sufficient amounts of water is essential for all living organisms. Maintaining water balance can be particularly challenging in xeric habitats, cold habitats where water remains mainly in a frozen state, and marine habitats with saline water. While the potential pathways by which animals obtain water are similar across species, the contribution of each source to the total body water pool varies considerably between species. Little research has been done to investigate how herpetofauna adjust specific pathways of water gain and loss to maintain water balance. To address this gap of knowledge, I examined the impact of metabolic rate, diet, and water availability on the oxygen isotopes in the body water pool of two reptile species, utilizing the novel method of interpreting Δ17O of body water, or Δ17OBW. I experimentally manipulated diet and temperature for captive collared lizards, Crotaphytus collaris, to evaluate how oxidase water and food water contribute to the total water balance. Temperature phases had a strong influence on water consumption and Δ17OBW values; however, Δ17OBW did not decline with increased metabolism or reduced food and water intake, contrary to expectations. An oxygen flux model could accurately predict Δ17OBW only under high-temperature conditions, suggesting that current models do not capture key aspects of water turnover in ectotherms under low- or moderate-temperature. I applied Δ17OBW to wild cottonmouth snake, Agkistrodon conanti, populations inhabiting both freshwater and marine island habitats. Field samples from all sites exhibited Δ17OBW values remarkably like those of meteoric water, indicating efficient water retention and potentially slow water turnover rates. However, once A. conanti is brought into captivity, Δ17OBW declined significantly under experimental hydration and dehydration, consistent with increased reliance on oxidase water. Captive A. conanti, regardless of hydration status, exhibited more negative Δ17OBW values than when sampled in the wild, possibly due to stress-induced metabolic shifts. Together, these findings highlight Δ17OBW as a powerful tool for inferring water sources and physiological states in reptiles, demonstrating that reptilian water balance may be more dynamic than previously recognized.

Rights

In Copyright. URI: http://rightsstatements.org/vocab/InC/1.0/ This Item is protected by copyright and/or related rights. You are free to use this Item in any way that is permitted by the copyright and related rights legislation that applies to your use. For other uses you need to obtain permission from the rights-holder(s).

DOI

10.25777/rcvs-2831

ISBN

9798293841714

ORCID

0009-0005-9089-9498

Download

Available for download on Sunday, September 19, 2027

Share

COinS