PS 6-83 - CANCELLED - Variation in pathogen exposure and persistence across a metapopulation of desert bighorn

Abstract: Desert bighorn (Ovis canadensis nelsoni, DBH) are a gregarious wild ungulate species inhabiting mountain ranges in the southwestern Unites States and Mexico. As habitat specialists, DBH occupy steep mountainous terrain separated by desert flats, forming metapopulations where occasional dispersal between mountain ranges creates a well structured and definable population network. In addition to host population connectivity, environmental variation among mountain ranges is likely to affect disease exposure risks to desert bighorn, shaping transmission opportunities for environmentally transmitted and vector-borne pathogens. Finally, desert bighorn have experienced notable effects from disease introduction from livestock, emphasizing the importance of understanding disease spillover in this system for management and conservation efforts. In this study, we use serological data for 12 viral and bacterial pathogens, collected from 1980-2022 across 18 populations in the Mojave desert of California to investigate spatial and temporal patterns of disease exposure across a natural metapopulation of desert bighorn. Specifically, we asses the roles of population connectivity, environmental variation, and parasite characteristics in shaping disease risks across our study populations. We found that spatial and temporal patterns are heavily dependent on pathogen characteristics. The seroprevalence of Anaplasma spp., a tick-borne bacterial pathogen, varied significantly with environmental characteristics important for vector populations. Some common pathogens of cattle, PI3, BVD1, and IBR, were rarely detected in this system but highly clustered in space and time to populations adjacent to grazing allotments and privately owned ranches, suggesting occasional spillover from livestock but a lack of sustained transmission in bighorn populations. Additionally, investigation of Mycoplasma ovipneumoniae and orf virus, two widespread respiratory pathogens that affect lamb survival, revealed that while orf virus showed little spatial or temporal pattern, M. ovipneumoniae experienced occasional extinctions and recolonizations among DBH populations. Further research on variation in population immune diversity and function may explain additional variation in pathogen persistence in the Mojave DBH metapopulation.