Trading-off and trading-up in the world of bacteria–phage evolution

• Published in: Current biology 2020-10, Vol.30 (19), p.R1120-R1124
• Main Authors: Burmeister, Alita R., Turner, Paul E.
• Format: Article
• Language: English
• Subjects: Adaptation, Physiological; Bacteria - metabolism; Bacteria - virology; Bacteriophages - physiology; Biodiversity; Biological Evolution; Ecosystem; Genetic Fitness; Humans; Models, Biological; Phenotype
• ISSN: 0960-9822; 1879-0445
• DOI: 10.1016/j.cub.2020.07.036

In 1979, Richard Law introduced the conceptual idea of the ‘Darwinian Demon’: an organism that simultaneously maximizes all fitness traits [1]. Such an organism would dominate an ecosystem, displacing any competitors and collapsing biodiversity to only a singular species. Surveying the tremendous species diversity of bacteria in the microbial world reveals that Darwinian Demons do not exist on Earth, and the popular notion is that fitness trade-offs generally constrain such possible evolution. However, the trade-offs faced by evolving bacterial populations presumably hinder their adaptation in ways that are not fully understood. In some cases, bacteria show evolved trade-ups, whereby selection causes multiple fitness components to improve simultaneously. Understanding these trade-offs and trade-ups, as well as their prevalence and roles in shaping microbial fitness, is key to elucidating how the incredible diversity of the Bacteria domain came to be, what maintains that diversity, and whether such diversity can be leveraged for technologies that improve human health and protect environments. Bacteria are under constant selective pressure and adaptation to one pressure can have pleiotrophic effects on other traits. In this essay, Burmeister and Turner discuss how lytic phages can select for evolution of phage resistance, thereby creating trade-offs that influence evolution of greater or lesser bacterial resistance to antibiotics.