PATHOGENS RANGING FROM INFLUENZA VIRUS TO BACTERIA IN HOSPITALS PERIODICALLY UNDERGO MAJOR EVOLUTIONARY JUMPS IN THEIR PHENOTYPES, ENABLING THEM TO EVADE HOST IMMUNE RESPONSES AND INTERVENTIONS. WE CONTEND THAT WHILE UNDERSTANDING THE GENETICS OF THESE EVENTS IS IMPORTANT FOR MITIGATING ASSOCIATED ADVERSE HEALTH OUTCOMES, SO TOO IS UNDERSTANDING THE ECOLOGICAL CONTEXT IN WHICH THESE EVENTS OCCUR. SEGMENTED VIRUSES TRANSMITTED BY MIDGES IN DIVERSE RUMINANT COMMUNITIES OFFER THE POSSIBILITY OF UNDERSTANDING HOW MULTIPLE INTERACTING MECHANISMS FACILITATE, OR LIMIT, OPPORTUNITIES FOR GENETIC EXCHANGE TO OCCUR BETWEEN DISTINCT VIRUS STRAINS THROUGH THE PROCESS OF REASSORTMENT. OUR STUDY FOCUSES ON BLUETONGUE VIRUS (BTV) AND EPIZOOTIC HEMORRHAGIC DISEASE VIRUS (EHDV), WHICH UNDERGO REASSORTMENT REGULARLY IN TRANSMISSION SYSTEMS WORLDWIDE AND IN OUR STUDY SYSTEM IN RANGELAND IN THE ROCKY MOUNTAINS. THE ECOLOGICAL CONTEXT FOR THE EMERGENCE OF REASSORTANT VIRAL STRAINS EMPHASIZES THE ECOLOGY OF THE CULICOIDES MIDGES THAT VECTOR THESE VIRUSES. LIFE TRAITS OF BOTH THE VIRUSES AND VECTORS ARE LIKELY TO BE HIGHLY TEMPERATURE SENSITIVE, WHICH WE HYPOTHESIZE AFFECTS THE RATE AT WHICH REASSORTMENT OCCURS AND WHERE REASSORTANTS ARE LIKELY TO BE TRANSMITTED BY VECTORS. THIS PROCESS FURTHERMORE TAKES PLACE IN THE CONTEXT OF DIVERSE RUMINANT COMMUNITIES AT THE DOMESTICATED ANIMAL - WILDLIFE INTERFACE, WITH INTERACTIONS AMONG THOSE ANIMALS LIKELY PLAYING A ROLE FOR DIVERSE STRAINS TO MEET AND FOR REASSORTANTS TO SPREAD. OUR PROPOSED STUDY SYSTEM IN NORTH AMERICA IS UNIQUELY VALUABLE FOR INVESTIGATING THIS DYNAMIC IN THAT IT OFFERS A PLATFORM TO INTENSIVELY STUDY ONE KEY MIDGE VECTOR SPECIES (C. SONORENSIS) BUT MULTIPLE WILD AND DOMESTIC RUMINANT HOST SPECIES ACROSS REGIONS WITH WIDE ECOLOGICAL GRADIENTS. THROUGHOUT, WE INTEGRATE LABORATORY, FIELD, AND MODELING APPROACHES TO ADDRESS THESE QUESTIONS.