Age-related variation in the oral microbiome of urban Cooper's hawks (Accipiter cooperii).

BACKGROUND: Bird species worldwide are affected by trichomoniasis caused by the protist Trichomonas gallinae. In avivorous raptors such as Cooper's hawks (Accipiter cooperii), nestlings are more susceptible than fledglings and adults. Previous research suggested a link between oral pH and susceptibility: the oral pH of fledgling and adult hawks is more than seven times more acidic than that of nestlings. We speculated that this age-specific difference in pH would correspond to age-specific differences in the oral microbiota of Cooper's hawks. We examined the oral microbiomes of 31 healthy, wild Cooper's hawks in Tucson, Arizona (USA). Individuals represented three age classes (nestlings, fledglings, and adults). We designed our study with multiple controls, replicated sampling, mock communities, and stringent quality-controls to address challenges that can limit the inferential quality of microbiome data sets. RESULTS: Richness of bacterial communities in oral cavities of Cooper's hawks differed as a function of age but not as a function of sex, sampling date, or sampling location. Bacterial communities in oral cavities of nestlings differed from those of fledglings and adults, whereas communities in fledglings and adults did not differ from each other. Communities were similar in males and females and did not differ over the sampling season. Prevalence of acid-producing bacteria in fledgling and adults vs. nestlings is consistent with previous reports of age-specific variation in oral pH, but further research is needed to establish a causal link to pH levels or susceptibility to disease. Analyses of mock communities demonstrated high repeatability and showed that operon number and read abundance were highly correlated. CONCLUSIONS: The oral microbiota of wild Cooper's hawks differs between nestlings and older birds. Variation in the oral microbiome is consistent with differences in oral pH between nestlings and older individuals. Overall our study provides a first perspective on bacterial communities associated with oral cavities of a wild raptor.

Using collections data to infer biogeographic, environmental, and host structure in communities of endophytic fungi.

Biodiversity collections contain a wealth of information encapsulated both in specimens and in their metadata, providing the foundation for diverse studies in fields such as ecology. Yet biodiversity repositories can present a challenge for ecological inferences because collections rarely are structured with ecological questions in mind: collections may be opportunistic in space or time, may focus on particular taxonomic groups, may reflect different collection strategies in different places or times, or may not be exhaustive in terms of retaining every specimen or having similar metadata for each record. In addition to its primary holdings, the Robert L. Gilbertson Mycological Herbarium at the University of Arizona holds a collection of living specimens of fungi isolated from the interior of healthy plants and lichens (i.e., endophytic and endolichenic fungi). Over the past decade, more than 7000 isolates from the southwestern United States were accessioned, including strains from diverse hosts in more than 50 localities across the biotically rich state of Arizona. This collection is distinctive in that metadata and barcode sequences are available for each specimen, many localities have been sampled with consistent methods, and all isolates obtained in surveys have been retained. Here, we use this herbarium collection to examine endophyte community structure in an ecological and evolutionary context. We then artificially restructure the collection to resemble collections more typical of biodiversity repositories, providing a case study for ecological insights that can be gleaned from collections that were not structured explicitly to address ecological questions. Overall, our analyses highlight the relevance of biogeography, climate, hosts, and geographic separation in endophyte community composition. This study showcases the importance of extensive metadata in collections and highlights the utility of biodiversity collections that can yield emergent insights from many surveys to answer ecological questions in mycology, ultimately providing information for understanding and conserving fungal biodiversity.

Aspergillus flavus diversity on crops and in the environment can be exploited to reduce aflatoxin exposure and improve health.

Humans and animals are exposed to aflatoxins, toxic carcinogenic fungal metabolites, through consumption of contaminated food and feed. Aspergillus flavus, the primary causal agent of crop aflatoxin contamination, is composed of phenotypically and genotypically diverse vegetative compatibility groups (VCGs). Molecular data suggest that VCGs largely behave as clones with certain VCGs exhibiting niche preference. VCGs vary in aflatoxin-producing ability, ranging from highly aflatoxigenic to atoxigenic. The prevalence of individual VCGs is dictated by competition during growth and reproduction under variable biotic and abiotic conditions. Agronomic practices influence structures and average aflatoxin-producing potentials of A. flavus populations and, as a result, incidences and severities of crop contamination. Application of atoxigenic strains has successfully reduced crop aflatoxin contamination across large areas in the United States. This strategy uses components of the endemic diversity to alter structures of A. flavus populations and improve safety of food, feed, and the overall environment.