CERES
Centre de formation sur l’environnement et la société

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David CLAESSEN

Maître de conférences (MCF-HC) - Associate professor
Director of the CERES (Centre de formation sur l’environnement et la société - Center for Environment and Society)

Address

David Claessen
Ecole Normale Supérieure
CERES and IBENS
24 rue Lhomond (CERES) / 46 rue d’Ulm (IBENS)
75230 Paris cedex 05

tel : 01 44 32 27 20 (CERES)
email : david (dot) claessen (at) ens (dot) fr
Office : room E050c (24 rue Lhomond)

CNRS affiliation :

Institut de biologie de l’ Ecole Normale Supérieure, CNRS-ENS-INSERM UMR8197,
Research team Eco-evolutionary mathematics (EEM)

Research interests

I am a researcher in the Eco-Evolutionary Mathematics (EEM) team of IBENS and the ENS, and also director of the interdisciplinary ENS Centre de formation sur l’environnement et la société (CERES). As such, my teaching and research are spread over two main axes : (i) theoretical evolutionary ecology and (ii) interdisciplinary environment-society studies. Yet there are strong links between these two axes. In both axes, my main interest is how feedbacks between different sub-systems govern their non-linear dynamics, and foster their emergent, intrinsic dynamics and resilience to perturbations. Examples of such coupled systems in my work are :
- genes-populations-dynamic landscapes ;
- populations-pathogens-climate ;
- biodiversity-crops-pathogens-farmers ;
- abiotic resources-biodiversity-exploitation (tragedy of the commons).
- socio-ecological systems including genetic evolution

This taste for interdisciplinary research is well illustrated by the Summer School, organised at CERES together with, among others, Corinne Robert (INRA). An important part of the summer school was the participation in one of the working groups, where participants worked together with one or more lecturers. The four main themes of the working groups were : Climate-economics, Ecology, Agro- ecology, Global carbon and nutrient cycles. Teachers included Mick Follows (ocean), André de Roos (ecology), Michael Ghil (climate-economics) and David Claessen (agroecology). One of the outcomes of this summer school is the current research collaboration with Corinne Robert and Francesco Accatino (INRA).

My research covers different aspects of theoretical ecology and evolutionary biology, including mathematical developments, computational approaches and the interface with controlled experiments. Topics include
- Ecology and evolution of physiologically structured populations
- Adaptive dynamics of complex ecological systems
- Evolutionary ecology of marine phytoplankton in simple and complex models

Mathematical models for understanding and predicting ecological and evolutionary processes – e.g. eco-evolutionary feedbacks, epidemics, evolution is spatio-temporally forced systems – pose challenges that involve fundamental as well as applied societal, aspects such as agricultural problems. In particular, temporally variable selective pressure (such as acting on crop pathogens), and trended variations (e.g. climate change) or regime-shifts (e.g. tipping points), are not well accounted for by classical models of adaptation, which are often linear in nature. I addresses the question of how such spatio-temporal variability affects the definition of fitness in general models for the evolution of quantitative traits. A good example of the latter is his work with Corinne Robert and Pierre-Antoine Précigout on evolution of crop pathogens in the typically spatio-temporally forced environment created by agricultural practices. We aim to enrich this kind of questions in the direction of socio- ecological systems.

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