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Clara Torres-Barceló (University of Montpellier) and colleagues introduce the Phylogenetic Host-Range Index (PHRI) — a new metric to classify phages as specialists or generalists based on bacterial genetic diversity.

Using phages infecting Ralstonia spp. from Mauritius and Reunion, they reveal context-dependent virulence–host range trade-offs and show generalist phages are more frequently targeted by CRISPR-Cas systems. Their work bridges ecological theory and application in biocontrol.