Hunting for 'factor X': the genetic basis of segmental mismatch.

Defending an evo-devo approach to the study of evolution in the pages of this journal may appear to be an unnecessary exercise. However, there are some case studies which, better than others, illustrate the necessity and the potential of considering developmental causes for explaining the evolution of organisms\u2019 body architecture. An example involving the evolution of segmentation in arthropods is the recent study by Janssen et al. (2008)