Adaptation to climate in widespread eucalypt species
Authors: Margaret Byrne, Suzanne Prober, Liz McLean, Dorothy Steane, William Stock, Brad Potts and Rene Vaillancourt
This project examined genetic divergence and phenotypic plasticity in two widespread Eucalyptus species (E. tricarpa in South-Eastern Australia, E. salubris in South-Western Australia), to determine the nature of adaptation to climate in these species, and whether genomic screening might be a useful tool to assess climate adaptation. Evidence of both plastic response and genetic specialisation for climate was found in both species, indicating that widespread eucalypts utilise a combination of both mechanisms for adaptation to spatial variation in climate. Widespread eucalypts are likely to possess a capacity to respond plastically to a changing climate to some extent, but selection of seed sources to match projected climate changes may confer even greater climate resilience. The assessment characterised responses in functional traits relevant to climate adaptation, including leaf size, thickness, tissue density, and carbon isotope ratio (?13C). Genetic variation was assessed with genome scans using DArTseq markers; outlier markers were identified as being linked to regions of the genome that are potentially under selection. Canonical Analysis of Principal Coordinates (CAP) analysis showed that the outlier markers were correlated with climatic variables, and some were also strongly correlated with functional traits. An Aridity Index was also developed from the CAP analysis that has potential as a tool for environmental planners to use for matching seed sources to target climates. Further study of the mechanisms of plasticity in response to climate may improve our ability to assess climate adaptation in other species, and to determine optimal strategies for ecosystem restoration and management under climate change.