Elizabeth Stacy (Life Sciences) and collaborators Michael Purugganan and Jae Young Choi (New York University) published a paper in Molecular Biology and Evolution, "Divergent Selection and Primary Gene Flow Shape Incipient Speciation of a Riparian Tree on Hawaii Island."  This work uses population genomics approaches to uncover the evolutionary history of a tree endemic to the rivers on east Hawaii Island and concludes that this taxon is a rare example of incipient sympatric speciation in trees. The findings indicate that strong selection — through the periodic submersion and mechanical stress experienced by riparian-zone plants during flooding — can drive the evolution of a novel morphotype from within a continuously distributed, long-lived, and highly dispersible tree species.