Research
Every organism consumes energy and resources to live, grow and reproduce. These transformations of energy move through populations and communities, fueling biological production and ecosystem processes such as the production of oxygen and the cycling of carbon.
The aim of the Functional Ecology group is 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.
We combine experimental manipulations of multi-species communities with high-throughput phenotyping to study the ecological and evolutionary mechanisms that influence energy fluxes at different scales of biological organization, from organisms to communities. Our model organisms include marine phytoplankton — tiny algae that are key players in ocean productivity and carbon uptake — and their invertebrate consumers.
The aim of the Functional Ecology group is 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.
We combine experimental manipulations of multi-species communities with high-throughput phenotyping to study the ecological and evolutionary mechanisms that influence energy fluxes at different scales of biological organization, from organisms to communities. Our model organisms include marine phytoplankton — tiny algae that are key players in ocean productivity and carbon uptake — and their invertebrate consumers.
|
|
How does competition affect organismal metabolism?
Energy use often varies widely among individuals of the same species and size. Some of this variation can be explained by differences in population densities. Organisms typically reduce metabolism in crowded conditions but few have shown why this plastic response occurs and how it changes over time. We have discovered that energy intake and metabolic expenditure decrease at different rates across population densities and that conspecific chemical cues reduce metabolism independently of food availability. Currently, we are studying how cell-to-cell interactions and bacteria affect metabolic phenotypes in phytoplankton. Understanding these mechanisms helps us predict how populations grow because metabolism affects the ability of an organism to compete and reproduce. Example papers: Lovass et al. 2020, Ghedini et al. 2017, Nørgaard et al. 2020 |
|
|
What are the temporal patterns of energy use in communities?
Energy use is often measured on individual organisms rather than on whole ecological communities directly. So the temporal patterns of energy fluxes in communities, and how they vary with respect to the strength of competition, biodiversity or disturbance remain unknown for many systems. To investigate these questions, we leverage high-throughput technologies that allow us to measure changes in resource use, metabolic costs and efficiency of whole communities over time. We found that competition among species increases community efficiency, a potential mechanism that increases stability and reduces invasion risk. Interestingly we discovered that, while biodiversity increases productivity, these effects are stronger in younger communities because competition suppresses metabolism as biomass accumulates. We are now testing how coevolution with competitors may affect the energy use of species, their coexistence (niche partitioning) and community productivity in phytoplankton. Example papers: Ghedini et al. 2021, Ghedini et al. 2020, Ghedini et al. 2018 |
|
|
How can we scale up species to community metabolism?
The metabolism of organisms scales predictably with size for many species. Similar scaling patterns also occur in whole communities but their origin remains unclear. For instance, some of our work has shown that, while the size of organisms is strongly related to their metabolism, size structure does not explain community metabolism as well. We are now studying metabolic plasticity within individual organisms and its density regulation to explain patterns of metabolic scaling and growth in whole communities. Ultimately, we aim to understand how the metabolic traits of organisms can be used to infer the functioning of ecosystems, and how much system-specific information we need to correctly predict functioning at larger scales. By doing so, we aim to reveal general principles for how metabolic phenotypes may affect the productivity and stability of ecosystems. Example papers: Ghedini et al. 2020, Ghedini et al. 2018, Ghedini et al. 2016 |
