Funded PhD opportunities

Ecological and evolutionary tradeoffs in specialised predators and prey

  • Application end date: 11th February 2018
  • Funding Availability: Funded PhD project (EU/UK students only)
  • Department: School of Biological Sciences
  • PhD Supervisor: Dr Trevor Willis, Prof Simon Cragg, Prof Fabio Badalamenti

Project code: BIOL3980218

Project description

How does a predator avoid causing local extirpation of its host by overgrazing before being ready to reproduce? How do prey species maintain adequate growth and reproductive rates in the face of continuous predation pressure? The overarching goal of this project is learn how ecologically specialised relationships develop between predators and prey, and how these relationships persist while balancing the reproductive and nutritional needs of both species. While there are many examples of narrow host preferences in terrestrial systems, and of how predator and host coexist, relatively few examples have been investigated in the marine environment. Many sessile marine invertebrates are colonial, and in temperate regions are subject to seasonally ephemeral lifecycles. Their predators are thus also only seasonally abundant, and we propose that it may be necessary to develop alternatives to classic predator-prey models to describe their population dynamics.

Opisthobranch molluscs, including nudibranchs, have undergone extensive species radiation and provide some of the best examples of marine specialists. Many species feed on just one or two prey taxa, larvae exhibit high levels of specificity during settlement, and many rely on settlement cues from the preferred host species. Many nudibranchs ingest and appropriate the stinging cells of cnidarian prey for their own defense – a strategy which is generally believed to form the basis for host specificity.

We propose to utilise the nudibranch mollusc Cratena peregrina and its host and prey, the colonial hydrozoan Eudendrium racemosum as a model system. Cratena is believed to be a significant structuring force in the population dynamics of Eudendrium, by feeding directly on the hydranths. No other prey species has been recorded for Cratena. However, recent work (Willis et al. 2017 Biol. Lett. 13: 20170447) has shown that the diet of Cratena is largely composed of zooplankton captured by the hydroid and ingested along with hydroid polyps. Elucidating the mechanisms by which this occurs will form part of the project. Using both field and laboratory experiments, we will make empirical estimates of energy transfer under varying scenarios to construct an energetics-based model that predicts optimal and sub-optimal conditions for persistence of the two species at both the population level and meta-population level. The model will ultimately be generalised to predict the persistence of benthic assemblages in the face of environmental change.

Supervisor profiles

Dr Trevor Willis

Prof Simon Cragg

Prof Fabio Badalamenti

Admissions criteria

You’ll need a good first degree from an internationally recognised university (depending upon chosen course, minimum second class or equivalent) or a Master’s degree in an appropriate subject. Exceptionally, equivalent professional experience and/or qualifications will be considered. English language proficiency at a minimum of IELTS band 6.5 with no component score below 6.0.

Specific candidate requirements

This study will suit a numerate and analytically minded student with a desire to work across disciplines. The project will involve a combination of field work at sea (including scuba diving), laboratory experiments, analytical chemistry and ecological and statistical modelling. Stable isotope analyses will be undertaken in collaborating laboratories, and training will be given. The student will garner a range of skills relevant to a research career, but applicable to multiple career paths.


Informal enquiries are encouraged and can be made to Dr Trevor Willis at (02392 845806) or Prof Simon Cragg at (02392 845808).

For administrative and admissions enquiries please contact

How to Apply

You can apply online at You are required to create an account which gives you the flexibility to save the form, log out and return to it at any time convenient to you.

A link to the online application form and comprehensive guidance notes can be found at

When applying, please quote project code: BIOL3980218.

Interview date: TBC

Start date: October 2018.

Funding notes

The fully-funded, full-time three-year studentship provides a stipend that is in line with that offered by Research Councils UK of £14,553 per annum.

The above applies for Home/EU students only.

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