Sébastien Portalier

McGill University
Ph.D. candidate

Supervisor: Gregor Fussmann
Michel Loreau, CNRS France
Start: 2010-09-01
End: 2016-11-30


The Effects of Physical Factors on the Structure of Food Webs
he topic of my PhD thesis is to model the structure of food webs. It involves developing mathematical and computer models that represent food webs in which species are engaged in biotic interactions (like predator - prey, and competition) and exposed to the effects of important abiotic factors (e.g. gravity, light intensity). In summary, this approach tries to build more realistic food web models that include the effects of environmental factors through some of the fundamental characteristics of species, such as their body size. The models are then applied to investigate exciting and somewhat untracked issues. For example, the models investigate why, in pelagic food webs, predators usually have a larger body size than their preys, and why this pattern is not as obvious in continental food webs (in which predators can be smaller than their preys). Another aspect explored is the structure of food webs along the vertical dimension of space (especially in aquatic ecosystems) and the relative influence of several physical factors (such as light availability, gravity, turbulence) on this structure.


1- Size-related effects of physical factors on phytoplankton communities
Portalier, Sébastien M.J., Mehdi Cherif, Lai Zhang, Gregor F. Fussmann, Michel Loreau
2016 Ecological Modelling