PINWORMS ARE ASSOCIATED WITH TAXONOMIC BUT NOT FUNCTIONAL DIFFERENCES IN THE GUT MICROBIOME OF WHITE-THROATED WOODRATS (NEOTOMA ALBIGULA).

Vertebrates rely on their gut microbiome for digestion, and changes to gut microbial communities can impact host health. Past work, primarily in model organisms, has revealed that endoparasites disrupt the gut microbiome. Here, using wild-caught white-throated woodrats (Neotoma albigula), we tested whether naturally acquired parasite infections are associated with different microbiome structure and function. We surveyed wild N. albigula in eastern Utah for gastrointestinal parasites in the spring and fall of 2019, using traditional fecal float methods and testing a PCR-based approach to detect infection. We tested whether the host gut microbiome structure and function differed based on infection with the most prevalent parasite, the pinworm Lamotheoxyuris ackerti. In spring, infected and uninfected animals had significantly different microbiomes, but these differences were not detected in the fall. However, for both sampling periods, infection was associated with differences in particular microbial taxa determined by differential abundance analysis. As N. albigula rely on their microbiomes to digest both fiber and the plant defensive compound oxalate, we compared microbiome function by measuring dry matter digestibility and oxalate intake in infected and uninfected animals. Although we expected infected animals to have reduced fiber degradation and oxalate intake, we found no difference in microbiome function using these assays. This work suggests that parasite effects on the microbiome may be difficult to detect in complex natural systems, and more studies in wild organisms are warranted.