Diffusion models for age-structured populations

This paper discusses some models for age-dependent populations with diffusion in one-dimensional environments. Three simple birth-death mechanisms are used. There are two diffusion processes: one represents random movement and the other movement to avoid crowding. The resulting models are reduced to systems of partial differential equations. These are sufficiently simple that an analysis of the interaction of diffusion and the birth-death processes is possible. An analysis is presented of the large-time behavior of populations in limited environments.