Theses and Dissertations

ORCID

https://orcid.org/0000-0001-6418-3801

Issuing Body

Mississippi State University

Advisor

Kouba, Andrew J.

Committee Member

Vance, Carrie K.

Committee Member

Allen, Peter J.

Committee Member

Roth, Terri L.

Committee Member

Songsasen, Nucharin

Date of Degree

12-8-2023

Original embargo terms

Campus Access Only 1 Year

Document Type

Dissertation - Campus Access Only

Major

Forest Resources

Degree Name

Doctor of Philosophy (Ph.D)

College

College of Forest Resources

Department

Department of Wildlife, Fisheries and Aquaculture

Abstract

Salamanders are one of the most at-risk taxa in the world due to habitat destruction, pollution, climate change, invasive diseases, and more. This has led to a need for conservation breeding programs that are often associated with zoos and aquaria. Salamanders can be difficult to breed in captivity, though, due to their dependence on specific environmental cues and other unknown factors that stimulate sperm and egg production. To overcome these challenges, assisted reproductive technologies (ART) such as exogenous hormone administration, sperm cryopreservation, and in-vitro fertilization have been developed to increase offspring propagation and maintain genetic diversity. If genetically robust populations of salamander species can be sustainably managed ex situ into the future, then their species can be protected in situ through practices such as reintroductions into native habitats. Given the importance of salamanders to healthy, functioning ecosystems, my doctoral research focused on methods to advance caudate conservation efforts through ART. This dissertation addresses four key areas targeting salamander reproduction for conservation: 1) Novel, non-invasive hormone administration routes; 2) Sperm extender toxicity; 3) Novel sperm cryoprotectants; and 4) Application of ART to target salamander species. The objectives were to: 1) Compare nasal, oral, and intramuscular delivery routes of gonadotropin-releasing hormone on spermic response; 2) Compare sperm extenders at varying osmolalities for maintaining sperm quality over time; 3) Test dimethyl sulfoxide versus dimethylformamide as cryoprotectants to increase frozen-thawed sperm viability, motility, and fertilization capability in the eastern tiger salamander (Ambystoma tigrinum); and 4) Transfer ART protocols developed from the eastern tiger salamander to the eastern hellbender (Cryptobranchus alleganiensis) and spotted salamander (Ambystoma maculatum). This work answers critical questions that should help advance salamander ART research into the future and lead to more sustainably managed caudate populations.

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