  We use the spherical evolution approximation to investigate nonlinear
evolution from the non-Gaussian initial conditions characteristic of the local
f_nl model. We provide an analytic formula for the nonlinearly evolved
probability distribution function of the dark matter which shows that the
under-dense tail of the nonlinear PDF in the f_nl model should differ
significantly from that for Gaussian initial conditions. Measurements of the
under-dense tail in numerical simulations may be affected by discreteness
effects, and we use a Poisson counting model to describe this effect. Once this
has been accounted for, our model is in good quantitative agreement with the
simulations.
