  Interactions between organisms are mediated by an intricate network of
physico-chemical substances and other organisms. Understanding the dynamics of
mediators and how they shape the population spatial distribution is key to
predict ecological outcomes and how they would be transformed by changes in
environmental constraints. However, due to the inherent complexity involved,
this task is often unfeasible, from the empirical and theoretical perspectives.
In this paper, we make progress in addressing this central issue, creating a
bridge that provides a two-way connection between the features of the ensemble
of underlying mediators and the wrinkles in the population density induced by a
landscape defect (or spatial perturbation). The bridge is constructed by
applying the Feynman-Vernon decomposition, which disentangles the influences
among the focal population and the mediators in a compact way. This is achieved
though an interaction kernel, which effectively incorporates the mediators'
degrees of freedom, explaining the emergence of nonlocal influence between
individuals, an ad hoc assumption in modeling population dynamics. Concrete
examples are worked out and reveal the complexity behind a possible top-down
inference procedure.
