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.
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