Inferring the Geographic Origin of Northwestern American Chestnut Trees Using ADMIXTURE
Faculty Mentor Information
Dr. Eric Friedlander, College of Idaho; and Dr. Robert Laport, College of Idaho
Presentation Date
7-15-2026
Abstract
The American chestnut tree (Castanea dentata) is a fast-growing deciduous hardwood tree native to the eastern United States that has been functionally driven to extinction within its native range by the exotic fungal blight Cryphonectria parasitica. Ongoing hybridization and genetic engineering efforts have produced blight-resistant C. dentata specimens but limited genetic diversity within these resistant populations necessitates further breeding efforts to create a diverse restorative population that can adapt to local pressures. While these efforts have primarily used rare reproductive remnant individuals as sources of genetic diversity, mature C. dentata specimens transplanted to the northwestern United States by westward migrants represent another potential genetic repository. To determine the geographic origin of these trees, we performed targeted sequencing on 64 C. dentata trees sampled in Washington, Oregon, Idaho, New York, Mississippi, and Tennessee and used ADMIXTURE, a population genetics software tool, to cluster these samples into populations. We found 2 distinct populations within our samples with a pairwise F_ST of 0.099, with all of our western samples belonging to the same population as the New York samples. These results suggest that the sampled trees could be utilized by breeding programs that aim to reestablish C. dentata in the northeastern United States.
Inferring the Geographic Origin of Northwestern American Chestnut Trees Using ADMIXTURE
The American chestnut tree (Castanea dentata) is a fast-growing deciduous hardwood tree native to the eastern United States that has been functionally driven to extinction within its native range by the exotic fungal blight Cryphonectria parasitica. Ongoing hybridization and genetic engineering efforts have produced blight-resistant C. dentata specimens but limited genetic diversity within these resistant populations necessitates further breeding efforts to create a diverse restorative population that can adapt to local pressures. While these efforts have primarily used rare reproductive remnant individuals as sources of genetic diversity, mature C. dentata specimens transplanted to the northwestern United States by westward migrants represent another potential genetic repository. To determine the geographic origin of these trees, we performed targeted sequencing on 64 C. dentata trees sampled in Washington, Oregon, Idaho, New York, Mississippi, and Tennessee and used ADMIXTURE, a population genetics software tool, to cluster these samples into populations. We found 2 distinct populations within our samples with a pairwise F_ST of 0.099, with all of our western samples belonging to the same population as the New York samples. These results suggest that the sampled trees could be utilized by breeding programs that aim to reestablish C. dentata in the northeastern United States.