During vertebrate development cells acquire different fates depending largely ontheir location in the embryo. The definition of a cell's developmentalfate relies on extensive intercellular communication that produces positionalinformation and ultimately generates an appropriately proportioned anatomy. Herewe place reaction-diffusion mechanisms in the context of general conceptsregarding the generation of positional information during development and thenfocus on these mechanisms as parsimonious systems for positioning anatomicalstructures relative to one another. In particular, we discuss the evidence forreaction-diffusion systems operating in the developing skin to yield theperiodic arrangements of hairs and feathers and discuss how best tobring together experimental molecular biology and numerical simulations to yielda more complete understanding of the mechanisms of development and naturalvariation.
