Testing the "Red King": The maintenance of functional diversity of hosts and parasites

Lead Research Organisation: University of Exeter
Department Name: Biosciences

Abstract

All organisms are challenged by a wide range of infectious organisms including bacteria, viruses, fungi and various worms. In response they have developed a wide range of resistance mechanisms ranging from thicker gut walls through to complex immune systems. When we look at populations of hosts we are struck by the differences between individuals in their relative resistance to their various diseases. This diversity is found in natural populations but also characteristic of human and farm populations. Furthermore there is considerable variation in the infectivity of different strains of the hosts various parasites. All of this variation is important because it allows rapid evolution in response to treatment and environmental change. It also allows populations to be resilient and affects the rate of transmission of a disease through a host population. However we do not know what processes generate and maintain the diversity in the first place. This proposal combines theory with experiments in the laboratory using microbes and their diseases and looks at a natural bacteria and its phage in order to try to understand what processes underlie the diversity. If we can understand these processes we will be able to manage disease in populations and potentially better protect species that are under threat of disease.

Planned Impact

The proposed work aims to give us a better understanding of the processes that underpin the evolution and maintenance of variation in hosts and their infectious disease. We are proposing a Blue skies research program, with its key benefits to the academic community, but the question is fundamental to infectious disease management. In particular, the most immediate beneficiaries are likely to be in agriculture where there is an increasing awareness of the role of diversity in both the host and the parasite. In particular, standing trait variation in parasites has the potential to lead to rapid evolution in response to different interventions including the use of GMOs. There is also the possibility of managing resistance to interventions in the parasite with the use of diverse hosts. At the moment there is relatively little communication between disease managers in the broadest sense and blue-skies evolution of disease work such as this. Much of the current modelling in the plant pathology world is based on gene-for-gene models dating from the 1940s, but our modelling program has the potential to lead to better modelling frameworks. We feel that it is important to engage with the more applied community directly by presenting and discussing our theoretical work and seeking application of our insights to particular important systems.

To help this process we will take advantage of two existing strategic alliances at the University of Exeter with Rothamsted and CEFAS. Our approach is to identify specific disease interactions where we feel that our models will be informative. We will then propose to visit the research groups involved and invite them to Exeter with the aim of creating an on going collaboration in applying evolutionary theory to disease management.

The microevolution of infectious disease has the potential to be of wide interest to the public and is therefore a good way of engaging people with evolutionary biology. In order to maximise the impact, we will work with a dedicated Research Development Manager (RDM) based in the Research and Knowledge Transfer Office. The dedicated RDM will draw on University wide resources including those available within RKT Office (50 + staff) but also the Press Office, the International Office and the Development and Alumni Relations Office to ensure that results of this project are disseminated in a timely and efficient manner. The project team will also organise a series of public lectures in schools and colleges in Cornwall, as they have successfully done for other members of the Centre for Ecology and Conservation. The PDRA will take an active role in public outreach, and to this end they will attend the NERC media training course.

We also see an exciting opportunity of engaging with the public through online resources. The aim is for the general public to interact with the theoretical models online in a game format that informs the processes leading the Red Queen and the Red King. Engaging participation in blue-skies research such as the Red King represents an opportunity for dissemination of the scientific process involved with exciting experimental work in novel ways, highlighting connections between theoretical work and issues of heightened public interest such as the management of infectious disease. Our main impact plan is to develop an online citizen science project where the public will be able to alter the parameters in the models to produce different patterns of diversity. Sonification of the results and gamification will engage with social media in order to raise interest in the modelling approaches and the evolutionary principles that underpin them.

Publications

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Antonovics J (2013) The origin of specificity by means of natural selection: evolved and nonhost resistance in host-pathogen interactions. in Evolution; international journal of organic evolution

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Ashby B (2015) Coevolution of parasite virulence and host mating strategies. in Proceedings of the National Academy of Sciences of the United States of America

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Bartlett LJ (2018) A genotypic trade-off between constitutive resistance to viral infection and host growth rate. in Evolution; international journal of organic evolution

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Best A (2013) The evolution of costly acquired immune memory. in Ecology and evolution

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Best A (2013) The evolutionary dynamics of within-generation immune priming in invertebrate hosts. in Journal of the Royal Society, Interface

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Best A (2017) Host-parasite fluctuating selection in the absence of specificity in Proceedings of the Royal Society B: Biological Sciences

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Best A (2014) The coevolutionary implications of host tolerance. in Evolution; international journal of organic evolution

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Boots M (2018) The evolution of constitutive and induced defences to infectious disease. in Proceedings. Biological sciences

 
Title The target of selection matters: an established resistance - development-time negative genetic trade-off is not found when selecting on development time. 
Description Trade-offs are fundamental to evolutionary outcomes and play a central role in eco-evolutionary theory. They are often examined by experimentally selecting on one life-history trait and looking for negative correlations in other traits. For example, populations of the moth Plodia interpunctella selected to resist viral infection show a life-history cost with longer development times. However, we rarely examine whether the detection of such negative genetic correlations depends on the trait on which we select. Here we examine a well-characterised negative genotypic trade-off between development time and resistance to viral infection in the moth Plodia interpunctella and test whether selection on a phenotype known to be a cost of resistance (longer development time) leads to the predicted correlated increase in resistance. If there is tight pleiotropic relationship between genes that determine development time and resistance underpinning this trade-off, we might expect increased resistance when we select on longer development time. However, we show that selecting for longer development time in this system selects for reduced resistance when compared to selection for shorter development time. This shows how phenotypes typically characterised by a trade-off can deviate from that trade-off relationship, and suggests little genetic linkage between the genes governing viral resistance and those that determine response to selection on the key life-history trait. Our results are important for both selection strategies in applied biological systems and for evolutionary modelling of host-parasite interactions. 
Type Of Material Database/Collection of data 
Year Produced 2020 
Provided To Others? Yes  
URL http://datadryad.org/stash/dataset/doi:10.5061/dryad.7sqv9s4q3