The role of space is more and more accepted as a way to dramatically improve the success of coevolutionary function approximation. The process behind this success however is not yet fully understood. It is suggested that spatiality causes a persistence in the population diversity over generations and a better targeting of weak points in the host-population by means of the parasite. In this paper we will discuss the role of spatial pattern formation and speciation in coevolutonary function approximation and the influence on the success rate of coevolution. We observe specific patterns of speciation in the problems as well in the problem solving-population(LISP functions). These patterns depend on a combination of the functions and the fitness criteria. The success of the spatial coevolutionary process can be understood from the speciation patterns: only if the problems speciate such that 'easy ones' are first evaluated, the coevolutionary process is successful. Categories and...