Host microbiome responses to the Snake Fungal Disease pathogen (Ophidiomyces ophidiicola) are driven by changes in microbial richness

Dermatophytic pathogens are a source of disturbance to the host microbiome, but the temporal progression of these disturbances is unclear. Here, we determined how Snake Fungal Disease progression resulted in disturbance to the host microbiome. To assess disease effects, 22 Common Watersnakes (Nerodia sipedon) were collected and half inoculated with O. ophidiicola. Epidermal swabs were collected weekly for use in microbiome and pathogen load characterization. For the inoculated treatment only, we found a significant effect of time on richness and Shannon diversity. When accounting for differences in assemblage richness, we found that microbial assemblages becoming more dissimilar across time in the inoculated but not the control group. Accounting for richness, average microbiome composition differed between treatments, but there was no interaction between treatment and time. These results suggest that changes in composition of the microbiome associated with disease occur due to disease-associated changes in microbial richness.