Metabolic efficiency reshapes the seminal relationship between pathogen growth rate and virulence

Abstract

A cornerstone of classical virulence evolution theories is the assumption that pathogen growth rate is positively correlated with virulence, the amount of damage pathogens inflict on their hosts. Such theories are key for incorporating evolutionary principles into sustainable disease management strategies. Yet, empirical evidence raises doubts over this central assumption underpinning classical theories, thus undermining their generality and predictive power. In this paper, we identify a key component missing from current theories which redefines the growth–virulence relationship in a way that is consistent with data. By modifying the activity of a single metabolic gene, we engineered strains of Magnaporthe oryzae with different nutrient acquisition and growth rates. We conducted in planta infection studies and uncovered an unexpected non‐monotonic relationship between growth rate and virulence that is jointly shaped by how growth rate and metabolic efficiency interact. This novel mechanistic framework paves the way for a much‐needed new suite of virulence evolution theories.

Microsporidian coinfection reduces fitness of a fungal pathogen due to rapid host mortality

“…However, an experimental evolution study that attempted similar selection failed to produce a response in M. bicuspidata (37). Alternatively, if slower parasite growth reduces parasite virulence and hence host mortality (consistent with the idea that higher virulence is associated with less prudent resource use (38)), there could be selection for slower growth of M. bicuspidata in response to O. pajunii. Unfortunately, experimental tests of this in this system seem unlikely to be successful, as multiple attempts to select M. bicuspidata for a variety of conditions have failed (37,39,40).…”

Feeding the fever: Complex host‐pathogen dynamics along continuous resource gradients

“…A large body of theoretical literature examines the proposition that the evolution of virulence is driven by trade‐offs between transmission and mortality impacts on hosts, and by the likelihood of co‐occurrence within individual hosts of competing parasite strains (Cressler et al, 2016 ). Recent work has demonstrated that resource availability can modulate how this evolutionary process plays out (Lindsay et al, 2023 ). It goes beyond the scope of this paper to explore the many ways that might happen, but we do note that if reduced resources reduce host population size, one might expect an evolutionary reduction in virulence.…”

With or without you: gut microbiota does not predict aggregation behavior in European earwig females

“…For instance, harsh environmental conditions are expected to favor group living if it increases protection from extreme temperatures, improves foraging efficiency and enhances defense against predators (Krause and Ruxton 2002). Conversely, several parameters are expected to inhibit the evolution of group living, such as its inherently higher risk of visibility to predators (Lindström 1989), reduced per capita access to resources (e.g., food, nesting material, mating partners), higher levels of inter-individual competition, expression of aggressive behavior and sexual harassment (Mosser and Packer 2009;Elwood and Stolzenberg 2020), and increased risk of encountering and transmitting parasites and pathogens (Deere et al 2021;Lucatelli et al 2021;Ritchie et al 2021;Lindsay et al 2023).…”