Date : 23/4/2010

Laboratory

Evology & Evolution CNRS-UPMC-ENS UMR 7625
Ecole Normale Superieure, 24 rue Lhomond 75005 Paris
Director : Minus VAN BAALEN

PhD Supervisor

David CLAESSEN
email : This e-mail address is being protected from spam bots, you need JavaScript enabled to view it
phone : +33 144322721

Subjects / Tools-Methodologies

1 : Evolutionary dynamics/Adaptive dynamics
2 : Ecological & biogeo dynamics/Population dynamics & MIT global circulation model
3 : Phytoplankton experimental evolution/Functional genomics

Summary of lab's interests

The laboratory’s research interests are in evolutionary ecology, with a strong focus on feedbacks between ecological and evolutionary processes. Main research axes are eco-evolutionary modeling, epidemiology, evolutionary microbiology and immunology, evolution of sociality, integrative ecology (including behavioural ecology and eco-physiology). The laboratory has interdisciplinary collaborations in the fields of conservation biology, biodiversity management and human health. The lab is strongly involved in the management and research activities of the ENS-CNRS Research centre in experimental and predictive ecology (CEREEP; Ecotron Ile de France). The PhD project will be done in collaboration with the ENS Molecular Plant Biology Laboratory (UMR 8197), where the experimental leg of the project will be done, under supervision of Chris Bowler (co-directeur de these). A second collaboration is with Mick Follows of MIT, Boston, a specialist in phytoplankton ecology modeling and global circulation models.

Summary of project

Some of the strongest interactions between ecological and climatic processes concern phytoplankton. While the importance of phytoplankton ecology for the global carbon cycle is well established, the role of their evolution is much less so. Adaptation is of particular importance in predicting the system\'s response to climate change, since it will modulate the ecological response to environmental change. Recent global ocean circulation models account for phytoplankton ecology. Here we propose to refine the definition of ecological processes and to allow for adaptation of phytoplankton cell size and shape in such models, as well as in more strategic models for freshwater systems. Phytoplankton communities are size-structured, and ecological functioning depends strongly on cell size and shape. Furthermore, phytoplankton size will influence the effectiveness of the biological carbon pump, through which carbon is sequestered from the atmosphere into the ocean interior by cell sinking. In addition, phytoplankton dynamics and evolution depend on interactions with higher trophic levels in the pelagic food web and these ecological interactions are generally also size structured. Phytoplankton ecology will be modeled by accounting for physiological structure (cell size, shape, nutrient quota) of phytoplankton communities and the size structure of the entire food web. The PhD student will study a range of models covering spatial scales from the global ocean to well-mixed lab cultures. Different theoretical issues will be tackled using models at different spatial and temporal scales. The experimental leg of the project will provide information to refine the modeling of (epi-) genetic adaptation of phytoplankton under environmental stress. The models will be used to formulate quantitative, testable predictions, which will be put to the test by using ecological and genomic data from the Tara Oceans expedition. The overall theoretical issue to be addressed is: does adaptation accelerate or mitigate the impact of climate change on the global carbon cycle?

Planned research activity:
The idea is to study the consequences of adaptation of cell size and shape for the phytoplankton’s ecological dynamics. The role of abiotic (climatic) forcing in these two aspects will be evaluated; as well as the feedbacks of the ecological and evolutionary dynamics for climate regulation through biogeochemical cycling. The project is interdisciplinary, combining ecology, evolution, (epi-) genetics, earth system science; as well as modeling, data analysis and experimental approaches. Adaptive dynamics theory and methods will be applied directly to the MITgcm model (Follows et al 2007). This is expected to give explicit answers to the question of the importance of adaptation for ecology-climate interactions through the carbon pump. The modified MITgcm model will allow us to simulate evolving phytoplankton in the context of climate change. The experimental leg of the project will provide invaluable information on the adaptive response of phytoplankton to changing conditions, both in functional terms (which traits change) as well as underlying molecular biology (observed genetic and epigenetic changes). These experimental results will feed the modeling work. Model predictions will be confronted to in situ and satellite data on ocean phytoplankton.

Innovative aspects and relevance:
The research questions posed here touch upon fundamental issues in several disciplines (ecology, evolutionary ecology, epigenetics, earth system science). We believe that this interdisciplinary collaboration between the complementary laboratories (Ecology and Evolution UMR 7625, Molecular Plant Biology UMR 8197, MIT) will be highly productive, exciting and dynamic, and will yield precious new clues about the likely interactions between phytoplankton and future climate change. The main expected scientific progress from this project is an improved understanding of the role of phytoplankton evolution in the response of ecosystems to climate change, and the consequences of this evolutionary response for feedbacks from the ecosystems to the climate.