Most heterotrophs feed on substrates that are poor in nutrients (especially nitrogen and phosphorus) compared to their demand, which leads to elemental imbalances that may constrain their growth and reproduction. Optimal carbon-to-nutrient ratio in acquired food can be achieved, e.g., by excretion of surplus C during assimilation. The ratio of C used for growth and reproduction over C consumed (CUE, carbon-use efficiency) however varies with substrate and organism stoichiometry. International research team including soil biologists Petr Čapek and Hana Šantrůčková from our department compiled a database of more than 2000 CUE estimates on a wide scale from microorganisms to invertebrates to vertebrates in aquatic and terrestrial ecosystems. Analysis of this unique dataset shows that the observed variable CUE values ensure optimal nutrient composition of the acquired resources in various environmental contexts and thus contribute to fitness maximization in heterotrophic organisms.

Stefano Manzoni, Petr Čapek, Maria Mooshammer, Björn D. Lindahl, Andreas Richter and Hana Šantrůčková: Optimal metabolic regulation along resource stoichiometry gradients. Ecology Letters 20, 1182–1191, DOI: 10.1111/ele.12815