The lamprey in evolutionary studies.

Lampreys are a key species to study the evolution of morphological characters at the dawn of Craniates and throughout the evolution of the craniate's phylum. Here, we review a number of research fields where studies on lampreys have recently brought significant and fundamental insights on the timing and mechanisms of evolution, on the amazing diversification of morphology and on the emergence of novelties among Craniates. We report recent example studies on neural crest, muscle and the acquisition of jaws, where important technical advancements in lamprey developmental biology have been made (morpholino injections, protein-soaked bead applications or even the first transgenesis trials). We describe progress in the understanding and knowledge about lamprey anatomy and physiology (skeleton, immune system and buccal secretion), ecology (life cycle, embryology), phylogeny (genome duplications, monophyly of cyclostomes), paleontology, embryonic development and the beginnings of lamprey genomics. Finally, in a special focus on the nervous system, we describe how changes in signaling, neurogenesis or neuronal migration patterns during brain development may be at the origin of some important differences observed between lamprey and gnathostome brains.