Date of Award


Publication Type

Master Thesis

Degree Name



Biological Sciences


Amphibians, Captive Breeding, In-Vitro, Sperm Quality, Zoo


Trevor Pitcher




Zoos can play a key role in ex-situ conservation, focused on the management of imperiled species whose survival is dependent on conservation programs to effectively breed and reintroduce individuals back into the wild. Consequently, captive bred populations rarely become self-sustained and zoos often become limited by small, ageing populations with reproductively exhausted individuals. To overcome reproductive challenges, zoos can employ exogenous hormones to induce gamete production for artificial fertilizations. Using the critically endangered Mississippi gopher frog (Lithobates sevosus), our research focused on these two aspects of reproduction in captivity. First, we examined the effects of age on sperm quality through the broader theory of senescence - the reduced survival or fertility with increasing age. We found that sperm quality significantly differed between age categories. Secondly, we evaluated the spermiation response and the quality of sperm release following an injection of an exogenous luteinizing hormone-releasing hormone. We found that sperm quality differed between sampling times post-hormone injection. Collectively, this thesis aimed to test age related hypotheses in the context of senescence theory, offer valuable information about hormone induction in a species of true frog, and provide feedback to zoos to help contribute to the reintroduction effort of the Mississippi gopher frog.