Samir Suweis — University of Padova #
Universal scaling laws link gene-abundance distributions to adaptive expression in diatom communities worldwide #
Marine microbes sustain Earth’s major biogeochemical cycles, yet how they maintain stable ecosystem functions across diverse environments remains unclear. We analyzed metagenomic and metatranscriptomic data from diatom communities sampled during the Tara Oceans global expedition. While gene abundance distributions remain statistically similar across samples, gene expression varies systematically across geographical locations. We show that this global pattern reflects predictable scaling laws \new{that link stable gene abundance reservoir} to functional responses. Global distributions, scaling relationships, and variability among sampling stations are captured by a stochastic model linking gene abundance dynamics to gene expression, which depends on the efficiency of transcription relative to degradation. While colder waters promote higher transcriptional activity and warmer regions show more selective gene usage, we find that transcript abundance increases nonlinearly with unigene richness. This general scaling is captured by our model and suggests that diatom communities balance high expression of core genes with specific functional diversity. These scaling relationships hold consistently across ocean basins, requiring only temperature to predict transcriptional patterns from genetic composition. Our findings reveal how \new{the stability of gene abundance structure in diatoms} ecosystems coexists with transcriptional variability, enabling flexible functional responses.