A scientific basis for assisted gene migration under climate change
Eucalypts are an iconic feature of the Australian landscape, providing food and habitat for many native Australian species. As such, they are of great ecological and economic value. However, the stability of Eucalyptus forests are under threat from human-related and natural impacts such as land-clearing and climate change, that are placing increasing pressures and stresses upon forest productivity, ecosystem services, and species diversity.
Climate change is altering temperature and rainfall regimes globally, with extreme weather events such as droughts and heatwaves expected to increase in their frequency, duration, and intensity in the future. In 2018, Australia – particularly New South Wales and the East Coast, have experienced severe and unseasonal heatwaves, with Western Sydney experiencing its hottest temperatures for nearly 80 years, and rainfall deficits that have made this year the eighth driest on record (Bureau of Meteorology, Dec 2018). With more than 700 species, the responses and adaptive potential to future climates of many eucalypts are not known.
My research, focusses on red gum Eucalyptus species (Subgenus: Symphyomyrtus; Section: Exsertaria), of Eastern Australia. These trees provide essential ecosystem services and forestry products, and are habitats and preferred food source for many of Australia’s native fauna, including koalas. In order to understand the ability of this group to respond to a changing climate, I will employ a complexity-reduction DNA sequencing method to determine the neutral genetic variation and the adaptive genetic variants to environment in four red gum species; Eucalyptus blakelyi, E. tereticornis, E. parramattensis and E. glaucina. This project will also look to determine the physiological tolerances and phenotypic plasticity of these species under drought-like conditions.
As such, the main questions I aim to answer are:
- Do these red gum species possess the adaptive genomic variants associated with varying climate regimes?
- Do the red gum eucalypts exhibit the phenotypic variation of key traits that allow for physiological tolerance and greater adaptive capacity under drier conditions?
- How frequent is hybridisation among these species in co-occurring areas? And is there evidence of genetic introgression of adaptive alleles between them?
As climate change continues to impact ecosystems across Australia, this study will help direct adaptive land management strategies, such as assisted migration, to ensure that Australia’s red gum forests possess sufficient genetic variation to tolerate future environmental change, and to maintain their health and productivity.
Figure 1: Eucalyptus blakelyi (Blakely’s red gum) woodland near Orange, NSW
Figure 2: Sampling of E. blakelyi
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Dr Paul Rymer, Distinguished Professor David Tissue, Dr Collin Ahrens