About the Partnership
This project is one of a number that are in competition for funding from the NERC Great Western Four+ Doctoral Training Partnership (GW4+ DTP). The GW4+ DTP consists of the Great Western Four alliance of the University of Bath, University of Bristol, Cardiff University and the University of Exeter plus five Research Organisation partners: British Antarctic Survey, British Geological Survey, Centre for Ecology and Hydrology, the Natural History Museum and Plymouth Marine Laboratory. The partnership aims to provide a broad training in earth and environmental sciences, designed to train tomorrow’s leaders in earth and environmental science.
Project Background
The end of the Pleistocene period was characterised by the extinction of large mammals worldwide. These large mammals are also known as Megafauna and their extinction was likely driven by a combination of climate change and human pressure (Barnosky et al. 2004). The timing of Megafauna extinctions falls between 50,000 and 10,000 years ago worldwide, with some variability between continents. Megafauna played important ecological roles in Pleistocene ecosystems including seed dispersal, controlling vegetation structure, and regulating fuel build-up and fire activity (Gill et al. 2012, Raczka et al. 2018, Hyvarinen et al. 2021). Megafauna extinctions are therefore thought to have had significant ecological consequences for the ecosystems that remained (Doughty et al. 2013, Faith et al. 2011). In tropical South America, information on these extinctions is limited even though it is estimated that 85% of Megafauna species went extinct. Current global environmental change is driving biodiversity loss and threatening species with extinction. Understanding the ecological consequences of Pleistocene Megafauna extinctions is crucial to estimate the potential repercussions of contemporary extinctions.
The study of megafauna extinctions in tropical South America is hindered by the limited number of Megafauna fossil sites discovered to date. Spores that germinate on herbivore dung can be used as an alternative to estimate Megafauna presence and declines (Davis & Shafer 2006, Perroti & van Asperen 2019). Dung spores are readily deposited and preserved in sediments along with fossil pollen and charcoal particles. Pollen and charcoal can be used to reconstruct vegetation composition and fire activity (Urrego et al 2016). The nature of macronutrient (C, N, P, K, Ca, Mg, and S) concentrations, spatial distributions and molecular speciations in sediments can be used to understand temporal changes in nutrient transfer in the environment (Adediran et al., 2021). Together, these integrated datasets can provide valuable information on the ecological consequences of Megafauna extinctions and the timing of Megafauna declines in tropical South America.
Project Aims and Methods
This PhD project will combine microfossils and spatial macronutrient analysis from sedimentary archives in tropical South America to address the following questions: i) what is the environmental setting prior to Megafauna extinctions?, ii) what is the timing of Megafauna extinctions in tropical South America?, iii) have vegetation composition and fire activity changed as a consequence of Megafauna extinctions? iv) can past and present soil macronutrient concentration and speciation be a consequence of Megafauna extinctions? The PhD project will also produce a regional synthesis of Megafauna extinctions and their ecological consequences across several sites in tropical South America.
Candidate requirements
The project is suitable for candidates with a degree in Geography, Biology or related physical sciences. The candidate will have a desire to develop field, laboratory and data analysis skills. For field trips, some knowledge of Spanish or Portuguese is desirable but not required.
Project partners
This project is a collaboration with the UK Centre for Multimodal Correlative Microscopy and Spectroscopy (CoreMiS) at the UKCEH. CoreMis is established based on the synchronisation of (i) Raman Imaging and Spectroscopy, with (ii) Scanning Electron Microscopy and (iii) Energy Dispersive X-ray Spectroscopy, as a single analytical suite (RISE-EDS), for multimodal and multidisciplinary environmental science research. With the unique capacity for simultaneous (i) physical (size/shape) analysis, (ii) multi-elemental (e.g., C, N, P, K) quantification and (iii) molecular speciation characterisation, RISE-EDS delivers a step-change in our ability to characterise materials and track biogeochemical changes from the macro to the nanoscale, across air, water, soil, plants, microbes and animals. CoreMis is the only facility in the UK with a RISE-EDS that is dedicated to the study of environmental samples. The platform also provides expertise in biogeochemical studies by synchrotron X-ray microscopy and spectroscopy (XAS). The PhD researcher will have access to CoreMis and explore opportunities for XAS studies at the Diamond Light Source UK, European Synchrotron Radiation Facility (ESRF) and Synchrotron Light Research Institute, Thailand.
Training
You will be based at the University of Exeter and part of your training will take place at CoreMis, UKCEH. The PhD researcher will be trained in tropical ecology, tropical palynology, statistical modelling, biogeochemistry, and sedimentology at Exeter. They will receive training in advanced microscopy and spectroscopy involving the use of Scanning electron microscopy, Raman imaging spectroscopy, Energy dispersive X-ray spectroscopy and Synchrotron X-ray atomic absorption microscopy and spectroscopy. Fieldwork will provide opportunities to visit and learn about biodiversity hotspots.
For further information and to submit an application please visit - https://www.exeter.ac.uk/study/funding/award/?id=4602
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