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Assessing the diversity, drivers & importance of Megaira, intracellular symbiont of aquatic eukaryotes

Project Description

The biology, ecology and evolution of eukaryotes is in part a product of their symbiotic interactions with microbes. Intracellular microbes, retained during cell division and reproduction, are particularly interesting, as they are selected to maintain and nurture their hosts. The effects they have on individuals then alters ecological and evolutionary dynamics – for instance, competitive ability, predator-prey dynamics, parasite-host coevolution.

Diverse aquatic microeukaryotes (algae, ciliates, ‘simple’ animals like Hydra) are infected with a rickettsial symbiont of the genus Megaira. We do not know what the effect is of the symbiont on the host individual, how the microbe is transmitted during sexual phases, or if the symbiont additionally shows infectious transmission. We also do not know how this symbiont might affect the interaction of its host with other symbionts with which it will share a cell. Following from these impacts on host individuals, we do not know how the symbiosis affects their host’s ecological and evolutionary dynamics.

In this project, we will 1) use microeukaryotic model systems (Paramecium, Volvox) to establish the impacts of symbiosis on individual hosts and 2) use microcosm experiments to determine their wider impact on ecological dynamics (e.g. intra and inter-specific competition, predator-prey dynamics).

Timeliness: We are beginning to understand how much of eukaryote biology and ecology is driven by microbes. However, most understanding has been gained from terrestrial arthropods, for instance the impact of Wolbachia and Rickettsia on host biology and evolution. This project will address the significance of a common but poorly understood symbiont in a very different set of hosts/environments.

Funding Notes

Competitive funding of tuition fee, research costs and stipend (£15,009 tax-free, 2019-20) from the NERC Doctoral Training Partnership “Adapting to the Challenges of a Changing Environment” (ACCE, View Website ). ACCE – a collaboration between the Universities of Liverpool, Sheffield,and York – is the only dedicated ecology/evolution/conservation Doctoral Training Partnership in the UK.

Applications (CV, letter of application, 2 referees) by email to deadline: January 8th 2020. Interviews in or after the week commencing : 10th February 2020. Shortlisted applicants will be interviewed for only one project from the ACCE partnership.


Nadal-Jimenez, P., Griffin J et al. (2019). "Genetic manipulation allows in vivo tracking of the life cycle of the son-killer symbiont, Arsenophonus nasoniae, and reveals patterns of host invasion, tropism and pathology." Environmental Microbiology 21: 3172-3182.

Pilgrim, J., et al. (2017). "Torix group Rickettsia are widespread in Culicoides biting midges (Diptera: Ceratopogonidae), reach high frequency and carry unique genomic features." Environmental Microbiology 19: 4238-4255.

Pritchard, J. O., Porter, A. H. M., & Montagnes, D. J. S. (2016). Did Gause Have a Yeast Infection?. The Journal of eukaryotic microbiology, 63(5), 552-557. doi:10.1111/jeu.12299

Minter, E. J. A., et al. (2018). "Variation and asymmetry in host-symbiont dependence in a microbial symbiosis." BMC Evolutionary Biology 18(1): 108.

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