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Open Access Highly Accessed Research article

Lotka–Volterra dynamics kills the Red Queen: population size fluctuations and associated stochasticity dramatically change host-parasite coevolution

Chaitanya S Gokhale1*, Andrei Papkou2, Arne Traulsen1 and Hinrich Schulenburg2

Author Affiliations

1 Evolutionary Theory Group, Max Planck Institute for Evolutionary Biology, August Thienemann Str-2, 24306, Plön, Germany

2 Department of Evolutionary Ecology and Genetics, Christian-Albrechts-University of Kiel, 24098, Kiel, Germany

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BMC Evolutionary Biology 2013, 13:254  doi:10.1186/1471-2148-13-254

Published: 19 November 2013

Abstract

Background

Host-parasite coevolution is generally believed to follow Red Queen dynamics consisting of ongoing oscillations in the frequencies of interacting host and parasite alleles. This belief is founded on previous theoretical work, which assumes infinite or constant population size. To what extent are such sustained oscillations realistic?

Results

Here, we use a related mathematical modeling approach to demonstrate that ongoing Red Queen dynamics is unlikely. In fact, they collapse rapidly when two critical pieces of realism are acknowledged: (i) population size fluctuations, caused by the antagonism of the interaction in concordance with the Lotka-Volterra relationship; and (ii) stochasticity, acting in any finite population. Together, these two factors cause fast allele fixation. Fixation is not restricted to common alleles, as expected from drift, but also seen for originally rare alleles under a wide parameter space, potentially facilitating spread of novel variants.

Conclusion

Our results call for a paradigm shift in our understanding of host-parasite coevolution, strongly suggesting that these are driven by recurrent selective sweeps rather than continuous allele oscillations.

Keywords:
Host-parasite coevolution; Red Queen hypothesis; Lotka-Volterra dynamics; Genetic drift; Population bottleneck