  This paper studies how patterns derived from a system of reaction-diffusion
equations may vary significantly depending upon boundary and initial
conditions, as well as in the spatial dependence of the coefficients involved.
From an extensive numerical study of the BVAM model, we demonstrate that the
geometric pattern of a reaction-diffusion system is not uniquely determined by
the value of the parameters in the equation. From this result, we suggest that
the variability of patterns among individuals of the same species may have its
roots in this sensitivity. Furthermore, this study analyzes briefly how the
inclusion of the advection and the space dependency in the parameters of the
model influences the forms of a specific pattern. The results of this study are
compared to the skin patterns that appear in Pseudoplatystom} fishes.
