On a system of reaction–diffusion equations describing a population with two age groups

A system of reaction–diffusion equations modelling a population divided into juvenile and adult age groups is studied. The system is not co-operative but its linear part is and this makes it possible to establish existence, non-existence and stability results for non-negative solutions of the system in terms of the principal eigenvalue of the corresponding linearized system.  2003 Elsevier Inc. All rights reserved.