Host diversity slows bacteriophage adaptation by selecting generalists over specialists

Area of Science:

• Evolutionary biology
• Virology
• Microbial ecology

Background:

• The selective pressures maintaining multi-host generalist viruses over single-host specialists are not fully understood.
• Understanding viral adaptation in complex host communities is crucial for predicting viral evolution.

Purpose of the Study:

• To investigate the evolutionary mechanisms that promote generalist viruses in multi-host environments.
• To determine how the number of hosts affects the rate of viral adaptation and host range.

Main Methods:

• Propagation of bacteriophage øJB01 in coculture with multiple host genotypes.
• Quantification of trade-offs in individual phage infectivity across different hosts.
• Sequencing of evolved phage to identify genetic basis of adaptation.

Main Results:

• Phage populations can adapt to new hosts, but increasing host diversity slows adaptation rate.
• Phage evolved in multi-host environments show increased generalist traits.
• Genetic analysis revealed strong selection and identified specific adaptations.

Conclusions:

• The addition of more potential hosts can select for low-fitness generalists over high-fitness specialists.
• Multi-host evolution alters the rate of viral adaptation and provides empirical support for generalist promotion.