Coinfecting parasites can modify fluctuating selection dynamics in host-parasite coevolution.

Area of Science:

• Evolutionary Biology
• Ecology
• Parasitology

Background:

• Host-parasite interactions can lead to coevolutionary fluctuations in genotype frequencies.
• These dynamics are often influenced by environmental factors and the presence of multiple parasite species.
• Coinfections can alter host and parasite performance, complicating coevolutionary outcomes.

Purpose of the Study:

• To investigate the effects of coinfections by genetically specific and nonspecific parasites on fluctuating selection dynamics.
• To model coevolutionary scenarios involving single infections, generalist coinfections with increased host costs, and coinfections with resource competition.

Main Methods:

• Utilized numerical simulations to model host-parasite coevolutionary dynamics.
• Compared scenarios with single, genetically specific parasite infections against those with additional generalist parasite coinfections.
• Incorporated parasite-induced host fitness costs and inter-parasite resource competition into the models.

Main Results:

• Coinfections can enhance fluctuating selection dynamics, particularly when they increase host fitness costs.
• Under resource competition, coinfections may either enhance or suppress fluctuating selection, contingent on parasite traits.
• Parasite fecundity and induced fitness costs significantly influence the outcome of competitive coinfections.

Conclusions:

• Coinfection dynamics are complex and can either stabilize or destabilize host-parasite coevolutionary fluctuations.
• The impact of coinfections is highly dependent on the specific ecological context and the characteristics of the interacting parasites.
• Understanding coinfection effects is crucial for predicting the long-term evolutionary trajectories of host-parasite systems.