The bacterial march toward symbiosis: on-ramps and off-ramps
Year: 2026
Type: review
Abstract: Host-associated bacteria are found across the tree of life. In this opinion article, we propose that population genetics theory can be used to probe the conditions that form the path toward such symbioses. We illustrate how mutation-selection models generate insights into the maintenance of a symbiont under transmission between generations and from the environment. We outline how basic features of host population size and life history shape the fixation of a heritable symbiont in a host population, suggesting elevated fixation probabilities in long-lived hosts. Finally, whenever the fitness effects of the symbiont vary over time, reduced efficiency of selection increases the fixation of a deleterious symbiont. Our predictions of the properties of hosts, symbionts, and their ecological contexts that impact symbiont establishment frame expectations across systems.
Source: Trends in Microbiology
Language: English
Subfield: Genetics
Domain: Life Sciences
Open Access status: hybrid
Estimated APC paid: $7,030
Funders: National Science Foundation, Gordon and Betty Moore Foundation, Nederlandse Organisatie voor Wetenschappelijk Onderzoek, Aard- en Levenswetenschappen, Nederlandse Organisatie voor Wetenschappelijk Onderzoek, National Institutes of Health, National Institute of General Medical Sciences, National Science Foundation Graduate Research Fellowship Program
Awards: Mohamed Donia Symbiosis in Aquatic Systems Initiative Investigator Award, Uncovering the modes and genetics of gut bacterial transmission, G3362510713, Grand Theft Aquatic: How a Sea Slug Steals Nutrition and Protection in a Three-Part Symbiosis, The genomics and consequences of gut bacterial adaptation to high-fat diets, G981345592
OpenAlex ID: W7163667376