Understanding the sublethal consequences of ophidiomycosis: lessons from pygmy rattlesnakes

Lind, Craig M.

Craig.lind@stockton.edu

Department of Natural Sciences and Mathematics

Stockton University

Galloway, New Jersey USA

Agugliaro, Joe

Department of Biological Sciences

Fairleigh Dickinson University

Madison, New Jersey USA

Farrell, Terence M.

Department of Biology

Stetson University

DeLand, Florida USA

It has been over a decade since the causative agent of ophidiomycosis (or snake fungal disease), Ophidiomyces ophiodiicola (Oo), was identified as a potential threat to pitviper populations in North America. Researchers have since employed a variety of strategies to better understand the causes and consequences of ophidiomycosis in snake populations, and much has been learned. However, an understanding of how host coping mechanisms interact with environment to drive disease outcomes remains a work in progress, rendering our understanding of the threat that Oo poses to snakes incomplete. Recent work has demonstrated that the fungus has been present in North American snake populations since at least the mid-20th century, but the spread of Oo in North America and the negative impacts observed in host populations may be emerging phenomena. We have tracked fungal disease since the 1990’s, and, in the last seven years, intensively studied the ecological and physiological correlates of ophidiomycosis in a population of pygmy rattlesnakes, Sistrurus miliarius, in Central Florida. Here we incorporate seasonal correlates of natural Oo infection into a framework to better understand the intrinsic and extrinsic drivers of ophidiomycosis in free-living pygmy rattlesnakes. Specifically, we highlight seasonal variation in disease prevalence and severity and describe endocrine, energetic, and thermal correlates of infection. Collectively, our results indicate that ophidiomycosis is associated with seasonal physiological responses that reduce host fitness. We also highlight current gaps in knowledge and avenues for future research that would improve on our current efforts to understand the population-level consequences of ophidiomycosis.