Persistent trade-offs balance competition and colonization across centuries.

Area of Science:

• Microbial Ecology
• Evolutionary Biology
• Bacteriology

Background:

• Microbial competition drives rapid adaptation and niche specialization.
• Adaptations enhancing competitive ability can create trade-offs, reducing performance in other environments.
• The persistence of such trade-offs in natural populations is largely unknown.

Purpose of the Study:

• To investigate the long-term stability of a trade-off between competitive ability and host colonization in natural Pseudomonas populations.
• To determine if evolutionary compensatory changes erode this trade-off over time.

Main Methods:

• Genomic surveys of natural Pseudomonas populations.
• Functional assays to assess competitive ability and plant colonization.
• Analysis of historical genomes spanning two centuries.

Main Results:

• A stable trade-off between competitive ability and plant pathogenicity (host colonization) was identified in natural Pseudomonas.
• Broadly lethal tailocins, while increasing competitive killing, compromise plant colonization.
• Genomic data indicate this trade-off has been maintained for at least 10^5-10^6 generations.

Conclusions:

• The trade-off between microbial competition and pathogenicity is fundamental and stably maintained in natural Pseudomonas populations.
• This trade-off is not transient and is resistant to erosion by compensatory evolutionary changes over long timescales.