The genes associated with climate-driven evolution of the black cottonwood tree are reported in a paper published online this week in Nature Genetics. The results may help conservation efforts for natural populations of plant species in the face of global climate change.
The black cottonwood tree, Populus trichocarpa, is natively found in an area spanning Alaska to Northern Mexico, with individual populations having adapted to their particular environment. It is the largest member of the willow family and is commonly used for timber and fuel, as well as playing an important role in local ecosystems.
Stephen DiFazio, Gerald Tuskan and colleagues studied the genomes of 544 black cottonwoods from British Columbia, Washington, Oregon and California to understand how the environment had shaped the trees’ evolution over time. The authors identified 397 regions of the genome that differed between populations and had likely changed relatively recently in response to the trees’ local environment. These regions were more likely to contain genes important for climate-controlled traits, such as tree height, tolerance to temperature stress and the timing of critical growth periods throughout the year.