Molecular Projects

Biogeography and Genetic Diversity in Northern Red Oak - Red oaks (Quercus section Lobatae) are native to the Americas and are now the dominant species in the eastern deciduous forests of North America. Within the last 100,000 years, northern red oak (Q. rubra L.), the dominant species among the red oaks, has endured multiple advances and retreats of the Laurentide ice sheet, active management by Native Americans, massive deforestation during European colonization and American westward expansion and, most recently, widespread fire suppression combined with repeated introductions of exotic pests and diseases. Postglacial migrations may have significantly influenced genetic diversity and population substructure in Q. rubra and the other closely related red oaks in eastern North America prior to significant anthropogenic disturbance.

The investigators are conducting range-wide studies of genetic diversity in the chloroplast and the nuclear genomes of red oaks. The distribution of chloroplast genotypes reveals the path of postglacial recolonization from southern sites. Nuclear genome polymorphisms reveal the extent of contemporary gene flow among and within populations of the same species and among red oak species. The chloroplast diversity studies reveal the response of red oaks to the last major climate shift in North America, the retreat of the Wisconsinian ice sheet. The nuclear genome data will enable us to accurately detect the frequency of hybrid offspring between red oak species and assess the impact of forest fragmentation on red oak genetic diversity.

Investigators: Jeanne Romero-Severson (The University of Notre Dame), Richard Jensen (St. Mary's College), and Scott Schlarbaum