Y-A+S is the new Y-A-S: Updating microbial life history tradeoffs with comparative genomics

Trait-based theory, coupled with mechanistic trait-based models, can be used to explore how changes in environmental conditions affect microbial community assembly and the impact on soil biogeochemistry. We used 27214 metagenome-assembled genomes (MAGs) and 5301 soil isolate genomes to investigate tradeoffs between life history strategies encoded in the genome. We used microTrait, a genome-based characterization toolset, to derive trait composition according to the YAS framework, which classifies microorganisms into high-yield (Y), resource-acquisition (A), and stress-tolerance (S) strategists. In contrast to the hypothesized three-way tradeoff, we observed a positive correlation between genome size and functional S and A traits and a negative correlation between genome size and the Y strategy measured as carbon use efficiency (CUE). Microbes with larger genomes favor investment in A and S at the cost of Y. Therefore, genome size, as a master trait, can enhance trait-based models by improving predictions of environmental impacts on soil microorganisms.