Model organisms in evo-devo: promises and pitfalls of the comparative approach.

Evolutionary developmental biology (evo-devo) is a rapidly growing discipline whose ambition is to address questions that are of relevance to both evolutionary biology and developmental biology. This field has been increasingly progressing as a new and independent comparative science. However, we argue that evo-devo's comparative approach is challenged by several metaphysical, methodological and socio-disciplinary issues related to the foundation of heuristic functions of model organisms and the possible criteria to be adopted for their selection. In addition, new tools have to be developed to deal with newly chosen model organisms. Therefore, we present a modelling framework suitable to integrate data on individual variation into evo-devo studies on new model organisms and thus to compensate for current idealization practices deliberately suppressing variation.