Characterization of Aoudad and desert bighorn sheep microbiomes in association to disease risk

Abstract

Bighorn sheep (Ovis canadensis) inhabit the western United States, northwestern Mexico, and some of southwestern British Columbia and Alberta. Many herds have encountered die-off events thought to be caused by a group of bacterial species referred to as the pneumonia complex, and this complex has been identified as transmissible to bighorn sheep from domestic sheep (Ovis aries) and goats (Capra hircus). It is also hypothesized that transmission may occur from Aoudad (Ammotragus lervia), an invasive species to Texas that occupies the same habitat as desert bighorn sheep (Ovis canadensis nelsoni) and is in the same subfamily (Caprinae). Microbiome dispersal is known to occur in other species through social behavior and shared resources. However, respiratory microbiomes in healthy bighorn sheep and aoudad are poorly known but characterizing healthy microbiome composition is important to understanding transmission as well as the baseline from which diseased state microbiomes depart. For example, some members of the pneumonia complex are often found in healthy bighorn sheep, but how their presence influences overall community structure is unknown. In this study, aoudad and bighorn sheep were identified carrying 243 bacterial species in nasal cavities in common and 202 bacterial species in throat cavities in common. Bacteria associated with the pneumonia complex were identified in both aoudad and bighorn sheep nasal and throat swabs. Nasal microbiomes between aoudad and bighorn sheep are more similar than nasal and throat microbiomes within the same animal species. Throat microbiomes follow a similar pattern between species. Spatial-temporal variation between bighorn sheep nasal microbiomes was significantly explained between mountain ranges and capture years. The discovery of Mycoplasma ovipneumoniae hosted in aoudad throat cavities was also included in this study.