Adaptive Capacity to Drought in the Diverse and Climatically Variable Plant Species in the Proteaceae Family
The Proteaceae plant family is highly diverse and widespread in Australia. They are thought to originate from rainforest biome in the ancient Gondwana and climate change has since shaped their distribution after the splitting, with relict rainforest genera (e.g. Placospermum, Buckinghamia, Musgravea) confined to refugia in eastern Australia (majorly Queensland). Some lineages have made transition into the drier habitat as in sclerophyllous communities (e.g Persoonia and Banksia) and others to a typical arid biome (e.g. Hakea and Grevillea). The Australian continent, which contains the highest diverse repository of this family, is currently experiencing devastating drought episodes and is predicted to increase in the future with climate change. Though climate change (e.g drought) is often predicted to cause widespread population or species local extinction, some species will not experience this limitation at their climatic range edge, suggesting the potential of phenotypic plasticity or genetic adaptation of traits in enabling some populations to persist under extreme environmental conditions. Hence, knowledge of drought tolerance and adaptive capacity of species is essential for predicting impacts on biodiversity and ecosystem function. At present, little or no studies have assessed the vulnerability of this family to drought. In addition, whether traits associated with drought (e.g hydraulic traits) can shift through these two mechanisms (phenotypic plasticity and genetic adaptations) still remains a puzzle.
The objective of this study is to determine drought vulnerability and adaptive capacity of plant species in the Proteaceae family through a comparative experimental framework. Using hydraulic trait (e.g P50-water potential inducing 50% loss of hydraulic conductivity and related functional traits, we will compare the vulnerability to drought (stem P50) of genera that have transitioned into the arid biome with mesic-restricted rainforest genera. Secondly, we have explored the Hakea genus using recent phylogeny to understand species-level physiological tolerance. Thirdly, I will be estimating the adaptive capacity of Hakea sp by growing distinct populations under contrasting watering treatments to estimate the contribution of the genetic and environmental components of phenotypic variance. Findings from this study will provide the scientific basis for adaptive management strategies for this family and facilitate management of native ecosystems, including threatened species in the NSW Saving Our Species program.
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Dr Paul Rymer, Distinguished Professor David Tissue, A/Professor Brendan Choat