Trees may be limited in how they can cope with climate change

Evidence for convergent evolution published in Science surprises researchers

Helen Metella and Matthew Pyper - 03 October 2016

Even after evolving independently for 140 million years, local populations of lodgepole pine and interior spruce use a high proportion of shared genes to adapt to the climate in which they live.

These findings, published in the journal Science, suggest that trees may not be able to adapt to climate change as well as expected.

"It was unexpected to discover that the underlying genetics are not all that complex and that the two different species of trees share many of the same genes responsible for adaptation to climate," said Andreas Hamann, a professor of forest genetics and global change biology in the Department of Renewable Resources and co-author of the study.

Genetic variation within wide-ranging species is critical for helping organisms adapt to local climate conditions. Scientists often believe that adaptation to climate is complex and involves many traits, genes and gene variants, which should allow evolution to find a great variety of ways for trees to thrive under various environmental conditions.

"The lack of different genetic solutions in species that have independently gone through many ice age cycles also implies that trees may be fundamentally limited to evolve new ways to cope with future climate change," said Hamann.

The finding is an important result from a Genome Canada "Large-Scale Applied Research Project" that started in 2011. The collaborative research project investigated how two of the most important forestry species in western Canada are adapted to climate, and how their seeds may be moved to new locations in reforestation programs to address climate change.

The discovery has valuable applications for managing reforestation under climate change. "If a limited set of variable genes is responsible for climate adaptation, then we can quickly and relatively inexpensively screen natural populations for relevant genetic differences, and match them to the right planting environments in reforestation programs," said Hamann.

Genomic screening could complement, and in the future potentially replace, long-term genetic field trials that are now required to investigate genetic adaptations of different seed sources used in reforestation. Currently, it can take up to 20 years to obtain the first relevant data from such trials as scientists wait for the trees to grow to maturity.

The research project was led by Sally Aitken from the University of British Columbia, and was co-led by Hamann.

The Science paper was senior-authored by team members now at the University of Calgary and Monash University, Melbourne.

The research was featured in a Science Perspectives companion article that explains the relevance and implications of the study in non-technical terms.