Host-parasite coevolution in populations of constant and variable size

Area of Science:

• Evolutionary biology
• Mathematical modeling
• Ecology

Background:

• Host-parasite interactions are often studied using matching-allele and gene-for-gene models.
• A unifying framework previously explored these models numerically in discrete time.

Purpose of the Study:

• To analytically investigate the unifying framework of host-parasite dynamics in continuous time.
• To generalize the model by incorporating changing population sizes due to antagonistic interactions.

Main Methods:

• Analytical investigation of a unifying host-parasite interaction model.
• Extension of the model to include Lotka-Volterra population dynamics.
• Analysis of allele frequency dynamics in continuous time.

Main Results:

• The generalized model reveals complex population dynamics, particularly as it shifts towards gene-for-gene interactions.
• Pure matching-allele models show single oscillation frequencies, while gene-for-gene-like conditions introduce a second frequency.
• These dynamics are general and applicable across various interaction parameters.

Conclusions:

• Inferred dynamical patterns of host-parasite coevolution are likely more complex than simple Red Queen dynamics illustrations.
• Parasite specificity, where one parasite infects multiple hosts, can significantly alter cyclic dynamics.