Emerging wildlife diseases represent a serious threat to conservation efforts. Impacts of emerging multi-host pathogens can vary greatly among species as well as geographically, and understanding which populations will be at greatest risk is essential for conserving biodiversity. Snake fungal disease (SFD), caused by the fungal pathogen Ophidiomyces ophidiicola, is responsible for lethal infections in snakes and has contributed to the decline of multiple North American snake populations. However, which species are most affected by this disease and how infections vary regionally remains unknown. Here we sampled 44 different species across 14 sites throughout the Southeastern and Mid-Atlantic United States. We found a strong effect of latitude on both pathogen prevalence and severity, with more severe infections at more northern latitudes. We also found high variability in pathogen prevalence and infection severity among species. There was a strong positive relationship between pathogen prevalence and disease severity, suggesting that SFD is not just highly prevalent in some populations but also highly virulent. More broadly, our results support that SFD likely has continued impacts on snake populations with some species experiencing greater disease than others attributed to spatial and host variation. / Master of Science / Conserving biodiversity is a significant challenge. Wildlife species are under multiple threats including habitat loss, changing climate, species introductions, pollution, and infectious diseases. Emerging wildlife diseases can pose a major problem for wildlife as they often go undetected until they cause substantial declines for the affected species, sometimes leading to population extirpations and extinction events. Snake fungal disease (SFD) is an emerging disease caused by the fungal pathogen Ophidiomyces ophidiicola, which has contributed to the decline of some North American snake populations. However, little is known about differences in infection, transmission, and host responses to SFD in a broader community context. To investigate the dynamics of this pathogen, we collected swab samples from 44 species from a total of 14 sites in New Jersey, Virginia, North Carolina, South Carolina, Georgia, Florida, and Louisiana. We sampled individual snakes to examine variation over a geographic gradient and among species. We found high variability among sites with more severe disease at northern sites. There was also high variability among species and some populations experienced both high pathogen prevalence and disease severity. Our results show that SFD is highly variable within snake communities and may still be causing population level effects.

Pathogenic fungi are increasingly associated with epidemics in wildlife populations and represent a significant threat to global biodiversity. Snake fungal disease is an emerging disease caused by the fungus, Ophidiomyces ophiodiicola, and appears to be widespread in the eastern United States. Yet an evaluation of field diagnostics, and an understanding of the population-level consequences of the disease, are lacking. First, I evaluated the use of clinical signs to predict the presence of O. ophiodiicola across season and snake habitat affiliation (aquatic or terrestrial) and I compared two sampling methods to see if collection method impacts PCR result. Overall, snakes with clinical signs had a higher probability of testing positive regardless of season or habitat association. However, terrestrial snakes had a lower overall probability of testing positive for O. ophiodiicola compared to aquatic snakes. I found no significant difference between sampling methods. Second, I used Passive Integrated Transponder (PIT) telemetry, and multistate capture-mark-recapture modelling to determine if SFD affects the short-term survival, movement, and behavior of wild snakes. I found no difference in short-term survival for snakes with SFD. Snakes with SFD spend more time surface-active and have lower permanent emigration and temporary immigration rates than snakes without SFD.

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<p>  </p> <p>Emerging pathogenic fungi have become a topic of conservation concern due to declines seen in several host taxa. One newly emerging fungal pathogen, <em>Ophidiomyces ophiodiicola</em>, has been well documented as the causative agent of Snake Fungal Disease (SFD). SFD has been found in a variety of snake species across the United States, including the Eastern Massasauga (<em>Sistrurus catenatus</em>), a federally threatened rattlesnake species. Most work to date has involved detecting SFD for diagnosis of infection through direct sampling from snakes. Attempts to detect <em>O. ophiodiicola</em> in the environment to better understand its distribution, seasonality, and habitat associations are lacking. I collected topsoil and ground water samples from four macrohabitat types in northern Michigan at a site where SFD infection has been seen in Eastern Massasauga. I used a quantitative PCR (qPCR) assay targeting the internal transcribed spacer region (ITS) developed for diagnosis of SFD after extracting DNA from samples. <em>Ophidiomyces</em> DNA was successfully detected in topsoil, with minimal to no detection in groundwater samples. The frequency in which <em>Ophidiomyces</em> was detected in a sample did not differ between habitats, but samples grouped seasonally showed higher detection occurring during mid-summer. Investigation of the correlation of environmental parameters on <em>Ophidiomyces</em> occurrence recovered no relationships. Our data suggests that season has some effect on the presence of <em>Ophidiomyces</em>. Differences between habitats may exist but are likely more dependent on the time of sampling and currently uninvestigated soil parameters. These findings build on our understanding of <em>Ophidiomyces</em> ecology and epidemiology and inform where snakes like the Eastern Massasauga may be encountering the fungal pathogen. Furthermore, they assist with developing conservation practices aimed at reducing <em>O. ophiodiicola </em>exposure in imperiled snake species. </p>

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