Trait-Based Life History Strategies Shape Bacterial Niche Breadth.

The ecological niche represents a fundamental property of organisms, reflecting their diversity of utilized resources or environmental tolerances across space and time. Despite a wealth of studies revealing that not all bacteria being everywhere, the key traits that determine niche breadth have remained unclear. Here, bacterial niche breadth based on a large-scale soil survey across a wide range of environmental gradients at a national-scale is characterized, and evaluated their life-history traits utilizing over 2000 bacterial genomic datasets from the Genome Taxonomy Database (GTDB). A positive relationship between gene functional diversity and niche breadth is found, and identified a key set of bacterial traits associated with niche breadth, which are assigned to five life-history categories, encompassing growth, competition, stress tolerance, resource acquisition, and dispersal ability. The traits of these categories are captured by distinct clusters in the full dimensionality of trait space, suggesting that a broad-niche taxon may indeed possess multiple facets of life history strategies essential for survival in diverse environments. Bacterial taxa with wider niche breadth maximized a diversity of traits associated with different life history strategies, whereas specialists tended to harbor a smaller number of traits associated with fewer life history strategies. Together, this study offers new insights into developing a trait-based understanding of bacterial niche breadth from the perspective of life history theory.