biostudies-literaturevon Meijenfeldt FABEuropean Research Council768-781https://www.ebi.ac.uk/biostudies/studies/S-EPMC10172124biostudies-literatureUnknown7(5)Generalists can survive in many environments, whereas specialists are restricted to a single environment. Although a classical concept in ecology, niche breadth has remained challenging to quantify for microorganisms because it depends on an objective definition of the environment. Here, by defining the environment of a microorganism as the community it resides in, we integrated information from over 22,000 environmental sequencing samples to derive a quantitative measure of the niche, which we call social niche breadth. At the level of genera, we explored niche range strategies throughout the prokaryotic tree of life. We found that social generalists include opportunists that stochastically dominate local communities, whereas social specialists are stable but low in abundance. Social geneNature ecology & evolutionA social niche breadth score reveals niche range strategies of generalists and specialists.PMC10172124865694Dutilh BEvon Meijenfeldt FABHogeweg PfalseA social niche breadth score reveals niche range strategies of generalists and specialists.Generalists can survive in many environments, whereas specialists are restricted to a single environment. Although a classical concept in ecology, niche breadth has remained challenging to quantify for microorganisms because it depends on an objective definition of the environment. Here, by defining the environment of a microorganism as the community it resides in, we integrated information from over 22,000 environmental sequencing samples to derive a quantitative measure of the niche, which we call social niche breadth. At the level of genera, we explored niche range strategies throughout the prokaryotic tree of life. We found that social generalists include opportunists that stochastically dominate local communities, whereas social specialists are stable but low in abundance. Social gene2023-01-01T00:00:00Z2023 May2025-04-22T13:10:33.164Z2025-04-06T00:31:23.115ZS-EPMC101721243701237510.1038/s41559-023-02027-7