AMERICAN CHESTNUT WAS ONCE A DOMINANT AND KEYSTONE SPECIES OF EASTERN HARDWOOD FORESTS, PROVIDING SUBSTANTIAL ECOSYSTEM SERVICES AND ECONOMIC BENEFITS. IN THE EARLY PART OF THE 20TH CENTURY, CHESTNUTS WERE DECIMATED BY AN EXOTIC FUNGAL BLIGHT. BILLIONS OF TREES WERE KILLED BY THE BLIGHT, ALTHOUGH THE SPECIES PERSISTS AS PERIODIC SPROUTS FROM UNINFECTED ROOTS. TWO PARALLEL METHODS HAVE EMERGED TO DEVELOP BLIGHT-RESISTANT TREES FOR REFORESTATION - HYBRID BREEDING AND GENETIC MODIFICATION- WHICH ARE BOTH NEARING THE GOAL OF ROBUST DISEASE RESISTANT TREES. HOWEVER, BEFORE WIDESPREAD RE-INTRODUCTION OF DISEASE RESISTANT CHESTNUTS TO NATURAL FORESTS CAN BE REALIZED, WE NEED TO INCORPORATE NATURAL ADAPTIVE GENETIC DIVERSITY. TO DO THIS, WE WILL COUPLE GENOME RE-SEQUENCING WITH MODERN ANALYTICAL TOOLS TO COMPREHENSIVELY CHARACTERIZE PATTERNS OF GENOMIC VARIATION IN WILD CHESTNUTS. SPECIFICALLY, WE WILL SEQUENCE THE GENOMES OF 500 TREES FROM ACROSS THE NATURAL SPECIES RANGE. WE WILL USE THESEDATA TO CHARACTERIZE CONTEMPORARY POPULATION CONNECTIVITY (I.E., BARRIERS TO POLLEN AND/OR SEED MOVEMENT); TO UNDERSTAND HISTORICAL DEMOGRAPHIC EVENTS THAT MAY IMPINGE ON GENETIC DIVERSITY ACROSS THE SPECIES RANGE; AND TO IDENTIFY RELATIONSHIPS BETWEEN GENOME AND ENVIRONMENT. THIS INFORMATION WILL BE USED TO DEVELOP A STRATEGY FOR VEGETATIVE PROPAGATION TO CONSERVE NATURALLY OCCURRING ADAPTIVE DIVERSITY IN WILD CHESTNUT TREES, WHICH WILL ALLOW US TO EXPAND THE GENOMIC VARIABILITY AND PROVIDE FOR LOCAL ADAPTION IN DISEASE RESISTANT POPULATIONS. THIS PROJECT PRIMARILY ALIGNS WITH THE 'LOCALLY ADAPTED CULTIVAR DEVELOPMENT' PROGRAM AREA PRIORITY.