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Date of Award
Spring 2024
Rights
Access restricted for 2 years to EWU users with an active EWU NetID
Date Available to Non-EWU Users
2026-06-13
Document Type
Thesis: EWU Only
Degree Name
Master of Science (MS) in Biology
Department
Biology
Abstract
Chytridiomycosis is an amphibian disease linked to population declines and species extinctions, caused by the fungal pathogen Batrachochytrium dendrobatidis (Bd). While chytridiomycosis can result in host death, some amphibians are less susceptible to severe infections through intrinsic factors including host-associated skin microbes aiding defense through resource competition and antifungal metabolite production. Amphibians can also release toxins in response to stress cues to defend against disease, parasitism, and predation. Tetrodotoxin (TTX) is a potent low molecular weight neurotoxin found in genus Taricha, and despite a previously observed negative relationship between differential levels of TTX concentration and Bd infection presence within a given locale, the influences of TTX concentration on microbiome diversity and pathogen dynamics remains unanswered. I examined the interactions of TTX concentration on Bd infection and microbiome composition in two Taricha newt species, Taricha granulosa and T. torosa, in the western USA. Among newt populations, there were significant differences in TTX concentration, but I found no evidence directly linking TTX concentration to Bd infection presence. In addition, I found significant correlations with microbiome structure and diversity; however, these dynamics were inconsistent across species. For example, T. granulosa, the species with higher TTX levels, exhibited a relationship between TTX concentration and the skin microbiome structure, while T. torosa did not. On the other hand, T. torosa exhibited a relationship between Bd and the microbiome, while T. granulosa did not. Microbes which potentially produce TTX collected from the skin of T. granulosa were also readily able to be cultured, but the relative abundances of those microbes exhibited no correlation with TTX concentration. Elucidating dynamics of the toxin-pathogen-microbiome relationships in vulnerable groups is necessary to further conservation efforts in even distantly related taxa by clarifying physiological and microbiome responses to antagonism.
Creative Commons License
This work is licensed under a Creative Commons Attribution-NonCommercial-No Derivative Works 4.0 International License.
Recommended Citation
Jost, Talon B., "Tetrodotoxin, fungal pathogen infection, and bacterial microbiome associations are variable in the skin microecosystems of two Taricha Newt species" (2024). EWU Masters Thesis Collection. 932.
https://dc.ewu.edu/theses/932
