Tracing the Maternal Line in Glacial–Interglacial Migrations of Populus tremuloides : Finding Trees for Future Sustainable Forests by Searching in the Past

Maintaining and planting sustainable forests is fundamental in perpetuating the essential functions of these ecosystems. A central aspect of managing forests for future resilience is the consideration of past migration and evolution of trees using genetic and genomic data to ensure that functionally appropriate diversity is conserved and utilized. In our study, we generated and compared genetic and genomic data from the plastome to better understand phylogeography and molecular evolution in the tree species Populus tremuloides (aspen). With these analyses, we found evidence of divergence and migration between northern and southern sites. Additionally, evidence of deep incomplete plastome sorting across the Salicaceae was found when examining insertion–deletion (indel) sites associated with DNA repair. By examining these indels in plastomic genes with introns across Salicaceae, we found a strong correlation between the abundance of DNA repair with genomic position and transcript abundance. From our findings, we conclude that previously ignored plastomic data are essential in understanding phylogeography and the evolution of key metabolic processes for improved aspen forest planning. Given the propensity of aspen forests to host high levels of biodiversity, rapidly sequester carbon, absorb excess nitrogen, and efficiently regulate snowmelt, improvements to planning and conservation will be highly impactful.