This lecture will examine the role of developmental gene regulation mechanisms in the evolution of vertebrate structures. While the natural selection of the most appropriate biological forms can be explained by the theory of evolution, the production of the diversity of these forms (variation) has yet to be integrated into this theory. Several mechanisms affecting our genetic heritage are probably involved, such as the appearance of mutations in important genes, chromosomal rearrangements, transposable element skipping or more or less subtle modifications of complex gene regulatory systems.
This lecture will look at some of these aspects, using vertebrate limbs as a model structure. These appendages enabled us to colonize the terrestrial environment during the Devonian period, some 370 million years ago, following a series of extraordinary events that led to their emergence from ancestral fins. Does today's detailed understanding of the regulation of limb-building genes in the embryo allow us to propose a molecular evolutionary blueprint for this major transition that marked the appearance of tetrapods and, consequently, Homo sapiens a few hundred million years later?