In this communication we propose a most general equation to study pattern formation for onespecies population and their limit domains in systems of length L. To accomplish this we include non-locality in the growth and competition terms where the integral kernels are now depend on characteristic length parameters α and β. Therefore, we derived a parameter space (α, β) where it is possible to analyze a coexistence curve α * = α * (β) which delimits domains for the existence (or not) of pattern formation in population dynamics systems. We show that this curve has an analogy with coexistence curve in classical thermodynamics and critical phenomena physics. We have successfully compared this model with experimental data for diffusion of Escherichia coli populations.