Genomic Data Suggests Pathways of Modern White Poplar (Populus alba L.) Range Formation in the Postglacial Era

The white poplar (Populus alba L.) is an economically significant tree species with a natural distribution spanning extensive region of Eurasia. Nevertheless, there is currently no hypothesis regarding the historical shaping of this range. In this study, we collected and sequenced 36 individuals of white poplar from disparate regions of Russia and Kazakhstan. Additionally, we employed available genomic data of white poplars from Italy, Hungary, and China. A genomic approach was employed to collate data on the location of glaciers in different periods, along with information on the natural and artificial distribution of white poplar. This enabled the formulation of the first hypothesis regarding the formation of the modern range of this plant. It is hypothesized that during the period of maximum glaciation, three refugia existed: the South European, Transcaucasian, and Altai-Middle Asian refugia. Post-glacial migration from these refugia led to the formation of modern populations of P. alba in Eastern Europe (including the European part of Russia), the Caucasus, and Siberia, respectively.