Understanding how species evolve in their communities is a key challenge in biology and has wide-ranging implications, from managing bacterial resistance to antibiotics to predicting changes in productivity under climate change. Except for bacteria, evolution in communities remains unexplored for most species. Living in a community can be both good and bad: co-occurring species can increase competition for resources but can also offer new opportunities not available for species in isolation. Can we predict how species traits related to energy use change over time in communities? How do these changes affect the productivity and efficiency of communities? This project explores these questions using phytoplankton as a model system. Phytoplankton plays a vital role in our oceans – not only it forms the base of marine food webs but also provides half of the world’s oxygen and carbon uptake. We will combine eco-physiological measurements of energy consumption and production with experimental evolution, leveraging new advances in phytoplankton genomics, to quantify change across three scales: genes, phenotypes and communities. With this multi-disciplinary approach, we will disentangle some of the mechanisms through which species interactions shape energy fluxes across biological scales. Furthermore, by tracking phytoplankton productivity and efficiency, we will provide new theory and data to test for changes in critical ocean functions, such as the production of oxygen and the uptake of carbon.

This project has received funding from “la Caixa” Foundation (ID 100010434) and from the European Union’s Horizon 2020 research and innovation programme under the Marie Skłodowska-Curie grant agreement No 847648. The fellowship code is LCF/BQ/PI21/11830001.

Although research has already revealed that the metabolism of organisms affects the productivity of populations and communities, the relationship between organismal metabolism and species interactions has yet to be explored. Hence, predicting the rates at which entire communities flux energy and resources remains difficult. Giulia´s previous work shows that the metabolism of organisms measured in isolation does not reflect their performance in communities because species interactions alter how organisms uptake and expend resources.

Understanding how such interactions affect metabolism is essential to estimating productivity and how it will change with biodiversity loss and global warming. Giulia’s ERC Starting Grant-funded project proposes to use marine phytoplankton as a model laboratory system to determine how metabolic responses to competitors affect coexistence and community functioning. The goal is to connect metabolic theory, which studies physical constraints on the metabolism of organisms in isolation, with community ecology, which centres on species interactions and emergent community properties. Based on Giulia´s preliminary data, the researcher will map metabolic responses between species that compete for similar resources and test whether these responses stabilise coexistence.

The project will allow Giulia and her team to leverage developments in transcriptomics of non-model organisms to identify the metabolic pathways that underpin metabolic responses. From this basis, the project will extend the analysis on larger temporal and biological scales, determine how warming modifies metabolic responses and community productivity, and how metabolism evolves in communities. Altogether, this project will demonstrate how metabolic adjustments influence the diversity and functioning of communities. The results will have broad implications for understanding biological systems because the metabolic impact of species interactions shapes the physiology and evolution of all organisms.

Funding