Summary Global warming can disrupt symbiotic relationships, leading to wide-scale ecosystem failures, such as coral bleaching. This project assesses analogue processes in the terrestrial realm, studying a key vegetation component – lichens Project background Lichens are a key component of the Earth’s vegetation; they are found in the largest terrestrial biome (the arid biome with 35% of the Earth`s land mass), and are also dominant epiphytes in temperate rainforests such as those in Scotland. Lichens are a component of the worldwide cryptogam cover that accounts for c. 50% of terrestrial N fixation and significant amounts of carbon capture (1,2). Lichens are fungi (mycobiont) that are symbiotic with photosynthetic green algal or cyanobacterial partners (photobiont). The mycobiont composes the major part of the lichen and recent reports indicate that the photobiont is the more adapted symbiont in this partnership and is thus more susceptible to change (3,4). Similar to processes in corals, the highly specialised photobiont suffers from elevated growth temperatures, which may lead to break up in the symbiotic relationship and lead to lichen death with global warming. This project will investigate the mechanisms driving lichen symbiosis and its resilience, by examining metabolic processes on the cellular level using protocols established for coral research and state of the art transcriptomics. Understanding these processes for a range of species will provide the mechanistic basis needed in assessing climate change risk and identifying threshold temperatures for lichen survival. Recent reports indicate that, for lichens, sensitivity to climate change remains a key area of uncertainty (5), weakening conservation policy Research questions The PhD project will address the following research questions: 1. What are the conditions that lead to a breakup of the lichen symbiosis? 2. What are the cellular processes driving the breakup of the symbiotic relationship? 3. How are the symbiotic exchange rates (sugars) between the two symbionts affected by single and multiple stressors? 4. Are some symbiotic-arrangements more heat-sensitive than others? Are there species with greater climate-sensitivity? 5. How will lichen distribution patterns be affected by climate heating? Methodology This project will analyse mechanisms, the cellular process and transcript dynamics involved in the lichens symbiotic relationship. The core methodology is based on experimental work simulating differentially stressful environments in growth chambers to test for stress physiology, the development of reactive oxygen species and carbon exchange rates between the symbionts. The student will have access to laboratory facilities, including gas chromatography–mass spectrometers, environmental growth chambers, Chlorophyll-Fluorometers and microscopes (including electron microscopy). The student will have the opportunity to establish novel protocols and will have significant scope to develop their own research ideas within the research questions. The project will involve fieldwork in Scotland. The project will involve close collaboration between the School of Geosciences and the School of Biological Sciences. Access to field sites and input on-site management will be provided from a non-academic collaborator ’Forest Research’, the UK’s principal organisation for forestry and tree-related research in support of sustainable.
Year 1: Pilot Study; Identification of model species; Literature review; Experimental design and first set of environmental simulation experiments (Physiological processes) Year 2: Data analysis; Submission 1st manuscript: What are the limits of the lichen symbiosis; Second set of environmental simulation experiments (cellular processes) Year 3: Data analysis; Submission of 2nd manuscript: How does increased temperature impact lichen physiology and growth Submission 3rd manuscript: What is the future of the lichen symbiosis?
A comprehensive training programme will be provided comprising both specialist scientific training and generic transferable and professional skills. The recruited student will gain skills in plant physiology and ecology, climate change science, experimental design, statistical analysis including modelling, open science best practice, science communication and field logistics. The PhD programme will benefit from international collaboration including with the University of Madrid, Spain and will provide opportunities for the recruited student to develop their own targeted research questions including through supervisory experience. The School of GeoSciences at the University of Edinburgh has a large research student cohort that will provide peer-support throughout the research program. The multi-disciplinary nature of the project and of the supervisory team will ensure that the scholar experiences training in multiple fields across different campuses, including biology and biogeochemistry. Analytical training will be provided by the supervisors or technicians for all instrumentation required