Navigating the Fitness Landscape: Host Density, Epistasis, and Clonal Interference Drive Divergent Evolutionary Pathways in Phage Qβ.

ABSTRACT: Understanding how ecological factors shape viral evolution is essential for predicting adaptation in RNA viruses. In this study, we investigated the evolutionary dynamics of bacteriophage Qβ under varying host densities, focusing on two nonsynonymous mutations-A1930G and C2011A-located in the A1 protein. Using experimental evolution, phenotypic assays, and competition experiments, we found that C2011A is consistently selected at low bacterial densities, enhancing viral entry but reducing burst size. In contrast, A1930G is fixed at high densities, despite similar phenotypic effects, suggesting its advantage arises from interactions with additional mutations. Clonal analysis revealed that compensatory or beneficial mutations modulate the fitness of A1930G, enabling its fixation. The absence

SUBMITTER: Laguna-Castro M 

PROVIDER: S-EPMC12469967 | biostudies-literature | 2025 Sep

REPOSITORIES: biostudies-literature