International PhD: How does host density and diversity affect disease outbreaks?

Opportunity Type: 
Student Opportunity
Closing Date: 
Saturday, August 10, 2019

The health and economic impact of recent outbreaks of Cholera, Zika virus and influenza underline the urgency of understanding how diseases spread and transmit. Transmission efficiency of many diseases is related to the density of the host populations. Lower host densities slow disease spread, until host densities are insufficient to maintain infection. Support for the existence of such host-density thresholds under which diseases cannot spread comes primarily from theory, with only a few empirical case studies. Considering that this theory is critical for our understanding of disease dynamics and forms the basis for vaccination and culling programs, it is thus surprising that the existence of host density thresholds has not been experimentally verified. Moreover, there are ample reasons why disease dynamics may be more complex than portrayed by simple theoretical models. Indeed, different assumptions on the genetic diversity of the host can lead to very different disease dynamics and abiotic (e.g. temperature) or biotic (predation, competition) factors may either facilitate or impede disease spread. To better understand how these factors impact disease outbreak and evolution and to validate the existence of host density thresholds, the candidate will induce epidemics under laboratory conditions with a model host-parasite system (the water flea Daphnia magna and the microsporidium parasite Ordospora colligata). Experiments could be supplemented with theoretical approaches in collaboration with Andrew Jackson (theoretician in the Zoology Department), genetic approaches to gain better insight in the role of host genetics, or field experiments, depending on the candidates interests and strengths. 

Research group: 
The candidate will be joining Floriane O’Keeffe, a PhD candidate starting in September and Pepijn Luijckx in the waterflea@tcd laboratory at the Zoology Department in Trinity College Dublin. The lab has a keen interest in empirically testing evolutionary and ecological theories pertaining to disease interactions. For example, past work has tested underlying assumptions of theory on host-parasite evolution (Luijckx et al. 2013 Current Biology), the evolutionary maintenance of sexual reproduction (Luijckx et al. 2017 PNAS) and how a warming climate may alter disease outbreaks (Kirk et al 2018). In addition to the waterflea@tcd laboratory the Zoology Department ( is home to research groups with expertise in theory (e.g. thermal scaling, host-parasite models), community ecology, parasitology, and aquatic biology providing ample opportunities for collaborative work. 

Interested candidates should e-mail me on and send: 
1) a curriculum vitae. 
2) a cover letter outlining your research interests and why you would like to do a PhD.

Fuding notes:
A four-year funded PhD position (€16,000 per year) starting either Sept 2019 or March 2020 is available at the Zoology Department of Trinity College Dublin. 

- Undergraduate or Master’s degree in ecology or evolution (or related field) and a keen interest in host-disease interactions. 

- Creative, motivated and resilient. 
- Experience running large laboratory experiments. 
- Experience with aquatic insects. 
- Knowledge of experimental design and experience using R. 
- Willingness to contribute to laboratory maintenance and animal care. 
- Capable of working both independently and as part of a team. 
- Proficient in written and spoken English.

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