Semester of Graduation

Spring 2021

Degree

Master of Science (MS)

Department

Veterinary Clinical Sciences

Document Type

Thesis

Abstract

Planet earth has now entered into its sixth mass extinction as a result of expanding human populations, posing an unprecedented threat to biologic diversity. Climate change, habitat fragmentation, wildlife trade, pollution, and biological invasions are just a few consequences of human activities that have directly contributed to unprecedented species extinctions. While widespread amphibian declines have gained more recent attention, it has been proposed that reptiles may be in even greater danger of extinction worldwide. Unfortunately, many reptiles are destined to go extinct before many of their basic biologic traits, including reproductive methods, have even been determined.

In order to mitigate the substantial loss to biodiversity that the impending decline of reptiles represents, development and employing additional methods of in-situ and ex-situ conservation strategies will be paramount. Although assisted reproductive technologies (ART) have been developed and successfully utilized in a handful of wildlife and domestic species, these techniques have been historically underutilized in reptiles. ART will not only enhance our understanding of reptile reproductive biology and physiology, but will facilitate conservation efforts in these species to overcome reproductive barriers and by preserving genetic material to protect biodiversity in the future.

The goal of this research was to use exogenous hormones in the male leopard gecko (Eublepharis macularius) as a model for the development of ART in geckos and other endangered lizard species. The study was conducted from September-December in the Northern Hemisphere. Single injections of human chorionic gonadotropin (hCG) at 50 IU or 100 IU were ineffective at increasing plasma testosterone concentrations within 24 hours of injection. Electrostimulation was successfully used to collect serial semen samples. Pregnant mare serum gonadotropin (PMSG) (20 IU, 50 IU) effectively increased testicular volume, spermatozoa concentration, motility, and the prevalence of morphologically normal sperm. Unilateral orchidectomies were successfully completed and allowed for histologic assessment of the testicles and epididymides without necropsy. PMSG was not successful at increasing circulating plasma testosterone concentrations. Ultimately, there is still time to prepare and slow the rate of global reptile declines. The development and refinement of ART in reptiles can aid in this mission to preserve biodiversity for future generations.

Committee Chair

Mitchell, Mark A.

Available for download on Tuesday, March 15, 2022

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