Persistence analysis of the age-structured population model on several   patches
  We consider a system of nonlinear partial differential equations that describes an age-structured population living in changing environment on $N$ patches. We prove existence and uniqueness of solution and analyze large time behavior of the system in time-independent case, for periodically changing and for irregularly varying environment. Under the assumption that every patch can be reached from every other patch, directly or through several intermediary patches, and that net reproductive operator has spectral radius larger than one, we prove that population is persistent on all patches. If the spectral radius is less or equal one, extinction on all patches is imminent. 
Vladimir Kozlov, Sonja Radosavljevic, Vladimir G. Tkachev, Uno   Wennergren
math.DS nlin.AO q-bio.PE