Project Description

A full project description can be found on Find a PhD.

Ecological communities are under extreme pressure worldwide. To guide conservation efforts and ensure that any interventions will be both appropriate and effective, we need to understand how communities work and respond to change. This requires understanding across all ecological functions and roles performed (not simply describing foodwebs). This project focusses on the regulatory effects of parasites in natural communities, a relatively neglected target for research, but probably a crucial part of ecosystem dynamics. Improving our knowledge of how parasite-host interactions provide regulatory function will substantially improve our understanding of their role in maintaining stability and resilience under perturbations (currently unexplained by the popular use of foodweb models).

The essential question is – to what extent do parasites contribute to the stabilisation of ecological communities? Arising from it, are the questions of how the putative regulatory function of parasites can be quantified, how it varies with parasite diversity and to what extent it remains effective as communities are progressively disrupted by species removal or introduction.
These questions will be addressed through combining mathematical (differential equation based) models of community dynamics, metabolic control theory (MCT) and in vivo meso/microcosm experiments comprising three trophic levels of invertebrates and a set of parasites. MCT has previously been used to quantitatively analyse cellular biochemical networks, incorporating multiple catalysts that collectively regulate the dynamic rates of the system. An advancement of the approach is ‘supply – demand theory’ (Hofmeyr & Cornish-Bowden 2000), and we will apply this in a novel way to investigate ecological networks by replacing reaction rates with predator-prey interactions (using functional response curves) and replacing catalytic enzymes with parasites as regulators.

In vivo experiments will be conducted in laboratory conditions using small systems of quick turnover invertebrate populations such as fresh water amphipods and isopods along with their natural parasites. Manipulations will involve replication of communities with differing parasite species and abundances, and the perturbation of these with challenges such as the introduction of an invasive competitor (Buck, 2019).

This approach will provide a comprehensive analysis of the contribution of parasites to system stability. The project will develop reasoning skills in quantitative ecology and mathematical modelling, and transferable skills including experimental design, good scientific practice, communication and independent research.

The applications and outcomes of the work will be of great importance to policy formation for whole ecosystem conservation. Through theoretical and empirical demonstrations of the critical role of parasites, this project will significantly advance our understanding of how each member population contributes to the stability of the system.

Essential skills

  • Mathematics: competence with ordinary differential equations and the basic models used in community ecology,
  • Written and verbal scientific English language to a high level of competence,
  • Quantitative and creative reasoning.

Desirable skills

  • Programming mathematical software (Matlab, Mathematica or similar),
  • Ecological lab work involving dissection of invertebrates to identify and count parasites and similar.


Photo by Erik Karits on Unsplash.


Keith Farnsworth

Primary Supervisor:

Profile: Keith Farnsworth
Institution: Queen's University, Belfast
Department/School: School of Biological Sciences

Thomas Bodey

Secondary Supervisor:

Profile: Thomas Bodey
Institution: University of Aberdeen
Department/School: School of Biological Sciences

Jaimie TA Dick

Additional Supervisor:

Profile: Jaimie TA Dick
Institution: Queen's University, Belfast
Department/School: School of Biological Sciences

Additional Supervisor:

Dr Alesandro Gimona
James Hutton Institute
Aberdeen site. Lead scientist in spatial ecology.


Hofmeyr, J-H. S. and Cornish-Bowden. 2000. Regulating the cellular economy of supply and demand. FEBS Letters 472:47-51.

Buck, J. C. 2019. Indirect Effects Explain the Role of Parasites in Ecosystems. Trends in Parasitology. 35(10):


It develops our understanding of the structure and resilience of natural ecological communities. This should enable us to better manage them and understand the effects of environmental change and threats. The impact will be better advice for ecological management delivered to governments at all levels and their agencies.

We do not yet really understand the way ecological communities work, having over concentrated on their partial representation as foodwebs. Research like this is the only way we can gain a more realistic – and thereby useful – model of their internal operation. To be clear, the research is general (applying widely and deeply), creative (genuine innovation), so its main impact is the improvement of human understanding, which is to say it will be a genuine advance in science and the authors hope that still counts for something.

The introduction of metabolic control theory to community ecology may have substantial applications because it applies generally. Wherever theoretical understanding informs conservation and ecological management, this approach can extend that understanding and improve our confidence in the scientific reasoning behind practical interventions. Through wide dissemination it would also contribute to broader appreciation of parasites as much more than enemies of their hosts. The explicit incorporation into this studentship of education and information dissemination of the insights gained will, if effective, improve the wisdom of those in frontline areas, such as agriculture and environmental policy making and implementation. Communicating more broadly through public discourse (e.g. “The Conversation”), enables this research to have a significant impact on society via improved appreciation of ecological communities as a whole. Improving understanding, broadly shared, is an improvement of humanity in general (and that is the founding aim of most universities in the world).


Proposed Timetable

Year 1.
Review literature on the regulatory role of parasitism in community ecology.
Establish a mesocosm / microcosm short-turnover experimental system including three trophic levels and a set of compatible parasites. Part of this work is intended to take place at the James Hutton Institute in Aberdeen.

Year 2.
Develop a mathematical model of a foodweb with parasites.
Develop a metabolic control theory (MCT) based method for analysing the system, along with standard stability and network analysis methods.
Conduct manipulation experiments on the in vivo experiment (different parasite sets and different environmental perturbations.

Year 3.
Analyse results of in vivo experiments (GLM based statistics).
Use the model to represent in vivo experiment and MCT analysis to examine state-space of the system and draw conclusions concerning the range of stability characteristics (resilience etc.).
Write up.

With a strong emphasis on publication and dissemination, throughout the project, the student will be mentored on manuscript preparation, conference delivery, networking and public dissemination.

The student will spend in the region of three months working at the James Hutton Institute in Aberdeen, mainly for performing laboratory based studies.


  • biodiversity
  • environmental-management


The James Hutton Institute

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