Henson et al. (1) illustrated that populations consisting of integer numbers of individuals cannot be modeled as a continuum without paying attention to the discrepancy between the dynamics of discrete and continuous systems. The inverse of this problem (i.e., discrete models for continuous dynamical systems) has been well investigated since the work of Ulam (2), and several fundamental results in that area (3-5) can be applied to the questions raised by Henson et al.

The stochastic lattice Ricker model we introduced for illustrative purposes is given by the map xt 1 int bxt exp c V xt zt , where zt is distributed normally with mean zero and variance one