Self-generated diversity produces “insurance effects” in biofilm communities

TLDR

Diversity is believed to shield communities from environmental instability, a concept known as the insurance hypothesis that has been tested across many ecosystems. RecA-dependent genetic changes generate diversification in *Pseudomonas aeruginosa*, altering traits such as biofilm behavior. During short‑term biofilm growth, *Pseudomonas aeruginosa* diversifies genetically, producing variants that either disseminate more rapidly or form biofilms faster, and this functional diversity increases biofilm resistance to stress, illustrating a biological insurance effect.

Abstract

Diversity generally protects communities from unstable environmental conditions. This principle, known as the "insurance hypothesis," has been tested in many different ecosystems. Here we show that the opportunistic pathogen Pseudomonas aeruginosa undergoes extensive genetic diversification during short-term growth in biofilm communities. The induced genetic changes are produced by a recA-dependent mechanism and affect multiple traits, including the behavior of the bacteria in biofilms. Some biofilm-derived variants exhibit an increased ability to disseminate, whereas others manifest accelerated biofilm formation. Furthermore, the presence of these functionally diverse bacteria increases the ability of biofilms to resist an environmental stress. These findings suggest that self-generated diversity in biofilms provides a form of biological insurance that can safeguard the community in the face of adverse conditions.