Decoupling function and taxonomy in the global ocean microbiome

TLDR

Microbial metabolism drives biogeochemical cycling, yet the ecological drivers of taxonomic variation across environments remain largely unknown. The study analyzes taxonomic and functional community profiles to identify factors shaping marine bacterial and archaeal communities worldwide. The authors classified over 30,000 marine microorganisms into metabolic functional groups to disentangle functional from taxonomic community variation. Environmental conditions strongly shape functional group distribution by defining metabolic niches, yet only weakly affect taxonomic composition within those groups, showing that functional structure and taxonomic composition are complementary, largely independent axes driven by distinct processes.

Abstract

Microbial metabolism powers biogeochemical cycling in Earth’s ecosystems. The taxonomic composition of microbial communities varies substantially between environments, but the ecological causes of this variation remain largely unknown. We analyzed taxonomic and functional community profiles to determine the factors that shape marine bacterial and archaeal communities across the global ocean. By classifying >30,000 marine microorganisms into metabolic functional groups, we were able to disentangle functional from taxonomic community variation. We find that environmental conditions strongly influence the distribution of functional groups in marine microbial communities by shaping metabolic niches, but only weakly influence taxonomic composition within individual functional groups. Hence, functional structure and composition within functional groups constitute complementary and roughly independent “axes of variation” shaped by markedly different processes.