Theses and Dissertations

Issuing Body

Mississippi State University


Willard, Scott T.

Committee Member

Kouba, Andrew J.

Committee Member

Lemley, Caleb O.

Committee Member

Feugang, Jean M.N.

Committee Member

Mitchell, Mark A.

Date of Degree


Document Type

Dissertation - Open Access


Animal Physiology

Degree Name

Doctor of Philosophy (Ph.D)


College of Agriculture and Life Sciences


Animal Physiology Program


Amphibians are key health indicator species and important sentinels for ecosystem health. With 32% of amphibians threatened with extinction, and an additional 25% without enough data on record to fully understand their status, amphibians are facing what is being called the Amphibian Extinction Crisis. Of caudate amphibians (salamanders/newts), 49.8% are threatened or endangered, making them currently the most threatened vertebrate taxa. As a result of the Amphibian Extinction Crisis, it is imperative that captive breeding facilities be established as a hedge against future amphibian extinctions. Unfortunately, captive assurance colonies face frequent failure due to lack of natural stimuli, which are necessary for amphibian breeding. Therefore, assisted reproductive technologies (ART) have been employed to reproduce endangered amphibians, increasing the success of captive assurance colonies worldwide. Over the last decade, a great deal of attention has been given to restoring anuran (frog/toad) populations through captive breeding, but little attention has been given to preservation of caudate species. Caudate amphibians are notoriously difficult to breed in captivity, thus it is crucial that ART be developed to help preserve endangered caudates sooner, rather than later. The following studies highlight some of the first attempts at developing ART protocols in caudate amphibians. Protocols were developed for: hormone induction of gamete production; cryopreservation of salamander sperm; and in vitro fertilization. These protocols were developed for the common, model species Ambystoma tigrinum in order to assure safety and efficiency for later application in endangered species.