Their new research, published in the journal eLife, should lead to improved decisions around where seeds are sourced during reforestation efforts to ensure that newly planted trees are diverse enough that some could tolerate harsher climates.
“Many species are facing rapid changes in their environments due to global climate change and other human disturbances,” said Dr Megan Supple, who led the study at the ANU Research School of Biology.
“Increased variation in a species’ genetic material, known as its genome, may allow a species to better adapt to these changes.”
Dr Supple said people working on projects to restore native plant communities needed to decide which seeds to plant at a given reforestation site.
“Genomic analyses can be used to identify source populations that are better adapted to the current and predicted climates at these sites,” she said.
“By selecting seeds with a high level of genomic diversity and adaptations to climate, the restored community will be more resilient to the changes they face in the future.”
Dr Supple and her team set out to discover if new genomic techniques could be used to help make scientifically informed decisions around seed sourcing for Yellow Box Eucalyptus trees.
“The Yellow Box, which has the scientific name Eucalyptus melliodora, is an important tree species in a critically endangered woodland community that now occupies just eight per cent of its former distribution recorded in the mid 1700s,” Dr Supple said.
The team genotyped 275 Eucalyptus melliodora leaf samples from mature trees at 36 sampling sites. Seeds were also collected from the sampled trees, where available.
“To find out an appropriate seed-sourcing strategy, we used the samples to examine the effects that geography and environment have on the distribution of genomic variation across the landscape,” Dr Supple said.
“Our analysis revealed that natural gene flow in Eucalyptus melliodora extends far across the landscape. This is crucial, because it means that seeds for re-establishing this species can be sourced broadly, rather than being restricted to local populations as is typically done.”
By generating a model that describes the relationship between genomic variation, geographic distance and environmental variables, such as temperature and rainfall, the team could identify seed sources that were well matched to a reforestation site.
Senior author Professor Justin Borevitz said that the team’s genomic analyses were based on mature trees that predated extensive land clearing for agriculture.
“It therefore remains to be seen whether human modifications of the landscape have disrupted the historical patterns of gene flow, resulting in more fragmented and inbred populations,” said Professor Borevitz from the ANU Research School of Biology.
“We hope our work will ultimately benefit Eucalyptus melliodora and other plant communities by providing a template for identifying suitable source populations for restoration, as well as identifying those populations that will likely be vulnerable to climate change.”
The paper ‘Landscape genomic prediction for restoration of a Eucalyptus foundation species under climate change’ can be accessed online for free at https://doi.org/10.7554/eLife.31835. Contents, including text, figures and data, are free to reuse under a CC BY 4.0 license.
Dr Megan Supple
Led the study as a postdoctoral researcher at the ANU Research School of Biology
Professor Justin Borevitz
Research School of Biology
ANU College of Science
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