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Doctor Anthea Challis

Candidature

Graduated PhD 2021

Thesis Title

Genetic adaptation and phenotypic plasticity influence trait expression under heatwave and water deficit conditions in the foundation tree, Corymbia calophylla

Research Project

Widespread tree mortality and dieback events have been increasingly observed globally throughout forests and bushlands as a response to periods of soil water deficit and heatwave events in recent decades (Allen et al. 2010). These events have been documented on all vegetated continents around the world (Allen et al. 2010; Meir and Woodard 2010; Lewis et al. 2011). Drought and heatwave events are projected to become more frequent and severe into the future throughout many regions around the world (Meehl and Tebaldi 2004; Dai 2013; IPCC 2014). This will likely lead to continued mortality and dieback throughout forests (Allen et al. 2015), however genetic adaptation and phenotypic plasticity of particular traits may enable trees to persist under these changing conditions.

The Mediterranean-climatic region of south west Australia (SWA) has experienced widespread tree death and dieback events in response to extended periods of water deficit and heatwaves in recent decades (Matusick et al. 2013; Challis et al. 2016). This global biodiversity hotspot (Myers et al. 2000) has experienced a 15-20 % decline in rainfall since the late 1960s (Bates et al. 2008) and further aridification (Shi et al. 2008) and increased frequency and intensity of heatwaves has been predicted (Bureau of Meteorology; Cowan et al. 2014). My PhD project aims to identify the capacity for genetic adaptation and phenotypic plasticity influencing tolerance to heatwaves and low soil water availability across provenances in the common, widespread SWA tree species, Corymbia calophylla (R. Br.) K.D. Hill & L.A.S. Johnson (Myrtaceae). To address this aim a number of reciprocal experiments have been conducted involving manipulation of temperature and water in common garden experiments.

Publications

Challis A, Blackman C, Ahrens C, Medlyn B, Rymer P, Tissue D, (2022) 'Adaptive plasticity in plant traits increases time to hydraulic failure under drought in a foundation tree', Tree Physiology, vol.42, no.4, pp 708-721

Esperon-Rodriguez M, Rymer PD, Power SA, Challis A, Marchin RM, Tjoelker MG, (2020) 'Functional adaptations and trait plasticity of urban trees along a climatic gradient', Urban Forestry and Urban Greening, vol.54, Article no.126771

Ahrens CW, Mazanec RA, Paap T, Ruthrof KX, Challis A, Hardy G, Byrne M, Tissue DT, Rymer PD, (2019) 'Adaptive variation for growth and resistance to a novel pathogen along climatic gradients in a foundation tree', Evolutionary Applications, vol.12, no.6, pp 1178-1190

Griffin‐Nolan RJ, Bushey JA, Carroll CJW, Challis A, Chieppa J, Garbowski M, Hoffman AM, Post AK, Slette IJ, Spitzer D, Zambonini D, Ocheltree TW, Tissue DT, Knapp AK, (2018) 'Trait selection and community weighting are key to understanding ecosystem responses to changing precipitation regimes', Functional Ecology, vol.32, no.7, pp 1746-1756

Challis A, Stevens JC, McGrath G, Miller BP, (2016) 'Plant and environmental factors associated with drought-induced mortality in two facultative phreatophytic trees', Plant and Soil, vol.404, pp 157-172

Supervisors

Distinguished Professor David Tissue, Dr Paul Rymer