Coexistence phenomena and global bifurcation structure in a chemostat-like model with species-dependent diffusion rates

François Castella (1, 2) , Sten Madec (3)

1 IPSO - Invariant Preserving SOlvers
2 IRMAR - Institut de Recherche Mathématique de Rennes
3 LMPT - Laboratoire de Mathématiques et Physique Théorique

We study the competition of two species for a single resource in a chemostat. In the simplest space-homogeneous situation, it is known that only one species survives, namely the best competitor. In order to exhibit coexistence phenomena, where the two competitors are able to survive, we consider a space dependent situation: we assume that the two species and the resource follow a di usion process in space, on top of the competition process. Besides, and in order to consider the most general case, we assume each population is associated with a distinct di usion constant. This is a key di culty in our analysis: the speci c (and classical) case where all di usion constants are equal, leads to a particular conservation law, which in turn allows to eliminate the resource in the equations, a fact that considerably simpli fies the analysis and the qualitative phenomena. Using the global bifurcation theory, we prove that the underlying 2-species, stationary, di usive, chemostat-like model, does possess coexistence solutions, where both species survive. On top of that, we identify the domain, in the space of the relevant bifurcation parameters, for which the system does have coexistence solutions.

Mots clés: Global bifurcation; Elliptic systems; Heterogeneous environ- ment; Coexistence Chemostat

Domaines: Equations aux dérivées partielles [math.AP]; Bibliothèque électronique [cs.DL]

François Castella, Sten Madec. Coexistence phenomena and global bifurcation structure in a chemostat-like model with species-dependent diffusion rates. Journal of Mathematical Biology, 2014, 68 (1-2), pp.377-415. ⟨10.1007/s00285-012-0633-7⟩. ⟨hal-00777025⟩