A large part of the answer to the problem of the diversity of animal form lies in the gene control circuitry, its structure, its functional organisation and its evolution . During evolution, gene duplications - thought to be massive events, even whole genome duplications in vertebrate species lineage for instance - have allowed changes in expression patterns to occur. As changes in pattern formation is of prime importance in the evolution of body plans, there is no doubt that the understanding of the massive gene duplication events, and of the molecular evolution of developmental regulatory systems will have a great impact on our understanding of morphological changes.

We are mainly interested in (1) how genes evolved and (2) what are the links between gene evolution and phenotype. We, as others, adress this questions by means of genetics and molecular biology performed in model organisms such as Zebrafish, Medaka, Xenopus, and Drosphila. However, we are also developing studies on non-model species such as Dogfish (chondrychtyans), in order to benefit from a huge set of ready-made successful genetic experiments: biodiversity.

We focused our attention on two gene-families : the homeotic genes (Hox genes) and distal-less-related (dlx) genes. Both encode multifunctional transcription factors that are involved in a wide array of developmental processes, such as the regionalisation of the body axis, the formation of central nervous system, the development of appendages, the development of teeth and scales... Not only the develoment and physiology of these organs have been well studied by biologists for decades, but also these organs retained the attention of evolutionary biologists and paleontologists because they represent informative steps during the evolution of vertebrates.