Giulia Ghedini Lab

Functional Ecology

Every organism consumes energy and resources to live, grow and reproduce. These transformations of energy fuel biological production and support ecosystem processes that are key to our life, such as the production of food and oxygen. The Functional Ecology group aims to understand how the environment (ecological context) regulates the rate at which organisms use energy and to identify general rules for how organismal processes scale up to determine the functioning of ecosystems.

The group works on phytoplankton as a model system because these tiny algae are key players in marine productivity and carbon uptake. By combining experimental manipulations of multi-species communities with metabolic phenotyping and methods from evolutionary biology, the group addresses three main questions:

1. How can we explain the recurrence of scaling patterns across biological scales?

The metabolism of organisms scales predictably with size for many species. Similar scaling patterns also occur in whole communities but their origin remains obscure. We study metabolic plasticity within individual organisms and its density regulation to explain patterns of metabolic scaling and growth in whole communities.

2. Can we predict how metabolic traits evolve in communities?

Species interactions affect how organisms uptake and expend resources but the evolutionary outcomes of metabolic changes in multi-species communities remain unclear. We study whether coevolution with multiple species predictably affects the energy use of organisms and its consequences for species coexistence (niche partitioning) and community productivity.

3. What are the mechanisms that underpin metabolic changes?

Phytoplankton interact tightly with other phytoplankton cells and with the bacteria with which they are associated. Cell-to-cell contact and phytoplankton-bacteria associations are some of the mechanisms that might affect the competitive ability and rates of energy use of other phytoplankton cells. We study the ecological and evolutionary consequences of these mechanisms on phytoplankton metabolism and how they are influenced by species diversity and environmental variability.

Through these questions that tackle change at three levels of biological organization – communities, populations and individuals – the group studies the relationship between the functioning of ecosystems, the traits of species and the mechanisms that affect energy fluxes at these different scales.