The Evolution of Virulence under Conditions of Frequent Multiple Infections
Ecology and Biodiversity of Animals and Ecosystems, Organismic Interactions
Final Report Abstract
Multiple infections are an emerging issue. Climate change causing shifts in parasite distribution and increased global travel and transport bring into contact parasites that have never before competed against each other, which can result in frequent coinfection scenarios. The goal of this research project was to investigate the long-term implications of coinfections by different parasite species on the evolution of virulence, using the water flea Daphnia and its microparasites as a model system. The project was a collaboration between a research team from Israel (Ben-Ami: TAU) and from Germany (Wolinska: IGB/FU). We combined a field study of temporary ponds in Israel with experimental studies exploring different conditions and implications of coinfections, both long- and short-term. Specifically, parasites that exploit different host tissues and/or different transmission modes were put together in competition. In addition, we explored different coinfections scenarios, such as varying the sequence of parasite encounters (i.e., whether the parasite is encountered by the host before or after the host had encountered another parasite species), and we investigated how host exposure to an environmental stressor (i.e., global pollutant - nanoplastics) affects the outcome of coinfection. In the field study, we found that the prevalence of hosts infected by more than one parasite species was almost perfectly fit to what is expected by chance, and that the relation among parasite community members appeared to be random. Highly prevalent parasite species were present in coinfections in high numbers, but even parasites with low prevalence could be found in coinfections with almost any other community member. In early season, when infection prevalence was under 40%, no coinfections were found in any of the populations. Later, the prevalence of coinfections became as common as single infections, occasionally exceeding it. Experimental results proved that environmental stressors can affect the performance of different parasites in diverging ways, with the potential to favor parasite coexistence. Moreover, our results showcase an example of sequential infections generating unilateral priority effects, in which antagonistic interactions between parasites can alleviate the intensity of infection and coincide with maladaptive levels of damage inflicted on the host. Finally, the samples from a large-scale long-term evolutionary experiment are currently being analyzed and the data processing and drafting of a manuscript will soon follow. This project, which resulted from a close collaboration between Israeli and German research teams, will further our understanding of the dynamics and impact of coinfections by different species on the evolution of virulence, and on host fitness.
Publications
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Genetic resistance and specificity in sister taxa of Daphnia: insights from the range of host susceptibilities. Parasites & Vectors, 12(1).
Orlansky, Sigal & Ben-Ami, Frida
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Temperature and host diet jointly influence the outcome of infection in a Daphnia‐fungal parasite system. Freshwater Biology, 65(4), 757-767.
Manzi, Florent; Agha, Ramsy; Lu, Yameng; Ben‐Ami, Frida & Wolinska, Justyna
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Sequential infection ofDaphnia magnaby a gut microsporidium followed by a haemolymph yeast decreases transmission of both parasites. Parasitology, 148(13), 1566-1577.
Manzi, Florent; Halle, Snir; Seemann, Louise; Ben-Ami, Frida & Wolinska, Justyna
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Temporal dynamics of freshwater planktonic parasites inferred using a DNA metabarcoding time-series. Parasitology, 148(13), 1602-1611.
Beng, Kingsly C.; Wolinska, Justyna; Funke, Elisabeth; Van den Wyngaert, Silke; Gsell, Alena S. & Monaghan, Michael T.
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Prior exposure of a fungal parasite to cyanobacterial extracts does not impair infection of its Daphnia host. Hydrobiologia, 849(12), 2731-2744.
Manzi, Florent; Agha, Ramsy; Mühlenhaupt, Max & Wolinska, Justyna
