Pheromones are chemosensory cues released by an individual to cause a behavioral or physiological change in a conspecific. These changes can range from increasing a female's receptivity to altering hormone secretions in the body. The red-legged salamander (Plethodon shermani) is an emerging non-mammalian model for understanding the evolution of chemical communication due to their well-characterized pheromones. Plethodontid salamanders secrete pheromones from their submandibular gland, called mental gland pheromones. Previous studies showed that mental gland pheromones increased receptivity in females during courtship and also increased corticosterone (CORT) concentrations in males. CORT is a metabolic hormone that mediates vertebrate stress responses. To further understand the neuroendocrine mechanisms involved in behavioral and physiological responses to pheromones, I conducted several experiments. First, I investigated whether pheromones altered levels of two neuromodulators in the brain, gonadotropin-releasing hormone (GnRH) and arginine vasotocin (AVT) in P. shermani. GnRH is both a neuromodulator and hormone, and has strong effects on reproductive behavior. Additionally, AVT has broad behavioral effects in vertebrates, particularly in newts. I found that application of mental gland pheromones altered the number of GnRH-immunoreactive neurons, but had no effect on the number of AVT-immunoreactive neurons. Second, I examined the effects of AVT and AVP antagonist on courtship and mating in dusky salamanders (Desmognathus spp.). There was no effect of AVT or antagonist on reproductive behaviors in dusky salamanders. Finally, I investigated the role of increased CORT concentrations in male P. shermani. I first validated a non-invasive method to transdermally deliver CORT through a dermal patch. I then used dermal patches to exogenously elevate plasma CORT and examine the effects of CORT on behavior (activity and chemoinvestigation) and metabolism. CORT had no effect on behavior, but increased metabolic rates in male red-legged salamanders. Together these studies provide insight into the mechanisms by which pheromones work to alter behaviors and physiological functions in vertebrates. / Bayer School of Natural and Environmental Sciences; / Biological Sciences / PhD; / Dissertation;

Thesis (Ph. D.)--Cornell university, 1912. / "Literature cited":p. 538-541. Also issued in print.

Thesis (Ph. D.)--Cornell university, 1912. / "Literature cited":p. 538-541. eContent provider-neutral record in process. Description based on print version record.

Thesis (M.S.)--Marshall University, 2008. / Title from document title page. Includes abstract. Document formatted into pages: contains viii, 137 p. Includes bibliographical references p. 131.137.

Theses (M.S.)--Marshall University, 2007. / Title from document title page. Includes abstract. Document formatted into pages: contains ix, 76 pages including illustrations and maps. Includes vitae. Bibliography: p. 65-71.

Thesis (M.A.)--Boston University

Upon exposure to environmental stressors, amphibians such as Plethodon montanus will release corticosterone (CORT) thus causing a behavioral and physiological response to cope with the stress. Currently, there are several invasive ways of collecting CORT in salamanders. However, these techniques typically require euthanasia of the organism. We hypothesized that exposure of P. montanus to stressful handling conditions will result in elevations of CORT that can be detected through dermal swabbing. To test this, two experiments were conducted which involved swabbing the dorsal side of the trunk before and immediately after exposing P. montanus to two different environmental stressors. The first experiment involved placing P. montanus into a behavioral chamber for twelve hours while the second experiment involved restraining P. montanus in a plastic bag with a damp paper towel for ten minutes. While both experiments indicated an elevation in CORT after the respective treatments, between-replicate variability were high, and the differences were not statistically significant. The results of the first experiment did reveal a stress response when P. montanus were taken out of the chamber. The second experiment’s results also suggested that P. montanus did have an acute stress response when restrained. Future studies could replicate this research, but with a larger sample size and see if the results are congruent with the data obtained in this study.

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