Symbioses are abundant, taxonomically widespread, ecologically important in a wide-range of habitats, economically important in agricultural systems, and consequently underpin the biodiversity and function of both natural and artificial ecosystems. It is crucial, therefore, to understand the ecological conditions that promote the evolutionary stability of symbioses so that the ecosystem services they provide can be maintained [1]. How and why stable symbiosis evolves is, however, challenging to explain. Our recent research points to a novel, potentially general mechanism by which symbioses originate. This evolutionary theory predicts that exploitative interactions will evolve into stable symbioses if the intracellular versus extracellular environments experienced by endosymbionts are contrasting and there are fitness trade-offs associated with adaptation to each environment [6]. These conditions are met by the model microbial symbiosis between the ciliate Paramecium and the green agla Chlorella, the Pb-C endosymbiosis, wherein the intracellular environment offers different biochemical and nutritional resources compared to the extracellular environment. These contrasting biochemical environments have driven divergence in metabolic traits between free-living and symbiotic clades of Chlorella, which we have been able to recreate using laboratory experimental evolution. In a current UKRI project, we have built a collection of >150 genome sequenced free-living and symbiotic Chlorella strains isolated from natural environments. This panel of diverse natural strains and associated lab evolved lines form an unparalleled toolkit for dissecting the molecular mechanisms that have enabled the evolutionary transition to stable endosymbiosis in Pb-C endosymbiosis.
Aims and Objectives: The overall aim of this project is to understand the diversity of metabolic strategies that have enabled the evolutionary transition to stable endosymbiosis in Pb-C. The specific objectives are:
- To use genome-guided multi-omics to characterise the metabolic diversity of natural endosymbioses.
- To use RNAi gene silencing to unpick the metabolic pathways that underpin living in endosymbiosis.
- To use laboratory experimental evolution to drive the evolutionary transition from free-living to endosymbiosis through metabolic selection.
Approach: To achieve these objectives, we will use a genome-guided multi-omics (transcriptomics, proteomics, and metabolomics) framework to understand how symbiotic and free-living Chlorella metabolism has diverged and is regulated. We will use cutting-edge RNAi gene silencing methods recently developed for this system by co-supervisor Richards to knock-down key metabolic pathways to directly test how these impact symbiosis. We will use our established evolve-and-re-sequence protocols to evolve free-living algae in biochemical environments designed to select for endosymbiotic traits based upon the multi-omic analysis, and test how these evolved changes impact the symbiotic ability of previously free-living lineages. Finally, we will use RNAi to validate adaptive mutations associated with the transition from a free-living to an endosymbiotic lifestyle.
Training: You will join 3 world-leading labs working at the cutting edge of mechanistic evolutionary biology. This project will offer an exceptionally broad multidisciplinary training, including evolutionary biology, biochemistry, genetics, microbiology. In addition, the student will gain experience of multi-omics techniques (including genomics, transcriptomics, proteomics, metabolomics) and associated bioinformatics. Training in experimental design and statistics. You will be based at the Manchester institute of Biotechnology, one of the leading institutes for biotechnology in the UK. We are home to over 40 research groups who lead a portfolio of pioneering research projects that continue to advance our knowledge and uses of biotechnology. Our biomolecular analytical facilities are truly World-class with dedicated technical specialists supporting a range of technology platforms, examples include bioanalytical techniques, directed evolution and molecular design through to synthetic genomics and modelling and data science.
Supervisors
Prof. Duncan Cameron (Manchester Institute of Biotechnology & Department of Earth & Environmental Sciences); Prof. Mike Brockhurst (School of Biological Sciences, Division of Evolution & Genomic Sciences) Prof. Tom Richards, Department of Biology, University of Oxford.
Entry requirements:
Applicants should have or expect to achieve at least a 2.1 honours degree in Microbiology, Ecology, Biology, Evolution
The duration of the PhD is 3.5 years and the proposed start date is September 2023.
How to apply:
You will need to submit an online application through our website here: https://uom.link/pgr-apply
When you apply, you will be asked to upload the following supporting documents:
• Final Transcript and certificates of all awarded university level qualifications
• Interim Transcript of any university level qualifications in progress
• CV
• You will be asked to supply contact details for two referees on the application form
• English Language certificate
You must contact the main supervisor to discuss the application before you apply. The email address for Professor Duncan Cameron is [Email Address Removed].
Equality, diversity and inclusion is fundamental to the success of The University of Manchester, and is at the heart of all of our activities. We know that diversity strengthens our research community, leading to enhanced research creativity, productivity and quality, and societal and economic impact. We actively encourage applicants from diverse career paths and backgrounds and from all sections of the community, regardless of age, disability, ethnicity, gender, gender expression, sexual orientation and transgender status.
We also support applications from those returning from a career break or other roles. We consider offering flexible study arrangements (including part-time: 50%, 60% or 80%, depending on the project/funder).
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