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Chevalier Mathieu



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Research interests :

Studies considering the impact of global changes on biodiversity mainly focused on statistical modelling of species distribution with the aim of projecting these distributions into the future under different climate change scenarios. However, these correlative studies are based on presence-absence data and generally disregard information on population abundances although abundances usually present strong spatio-temporal variations at a local scale that can have broad impact on ecosystem functioning and biodiversity. Beyond the better resolution provided by abundance data relative to presence-absence data, population size and population trends are the most frequently used measures to assess the conservation status of species and determine priority actions. Studying population dynamics should therefore help identify the determinants of population abundances and notably the impact of global changes on organisms, species, and biodiversity which should ultimately help refine conservation strategies.As fish are ectothermic organisms, they are expected to be strongly affected by climate warming. Using the fish database of the French Office of Water and Aquatic Ecosystems (Onema), I use different statistical approaches (both under the frequentist and the Bayesian framework) to identify the determinants of spatio-temporal variations in population abundances. My particular aim is to determine whether temperature is influencing freshwater fish population dynamics while accounting for density dependent processes in order to identify population or species extinction risk.

Across the past few decades, large interspecific differences in species responses to climate change have been revealed. Such differences could be the result of different exposure to climate change or of differential sensitivities to climatic variations due for instance to physiological limits, habitat or trophic specialization, life-history characteristics or obligate trophic interactions. By working on several species, I also try to relate interspecific differences in population dynamics (more specifically on intrinsic and extrinsic parameters driving population dynamics) to several species characteristics related to their life-history strategies, ecology and physiology to identify the intrinsic determinants of species-specific responses to climate change.

I am also interested in fish community rearrangements in the global warming context and its impact on ecosystem functioning.

Publications :

Chevalier M., Laffaille P., Ferdy J.B. & Grenouillet G. (2015). Measurements of spatial population synchrony : influence of time series transformationsOecologia. doi : 10.1007/s00442-015-3331-5.

Rajon, E., Desouhant, E., Chevalier, M., Débias, F. & Menu, F. The Evolution of Bet Hedging in Response to Local Ecological Conditions (2014). The American Naturalist 184(1) : E1-E15.

Lin, M.*, Chevalier, M.*, Lek, S., Zhang, L., Gozlan, R.E., Liu, J., Zhang, T., Ye, S., Li, W. & Li, Z. Eutrophication as a driver of r-selection traits in a freshwater fish (2014). Journal of fish biology. (* These authors contributed equally to the work).

Chevalier, M., Laffaille, P. & Grenouillet, G. Spatial synchrony in stream fish populations : influence of species traits (2014). Ecography 37 : 001-009.

Paz-Vinas, I., Comte,L.Chevalier, M., Dubut, V., Veyssière, C., Grenouillet, G., Loot, G. & Blanchet, S. (2013). Combining genetic and demographic data for prioritizing conservation actions : insights from a threatened fish species. Ecology and Evolution 3 : 2696-2710.