Guest Edited by Mansi Srivastava and Deirdre Lyons
Understanding how diverse animal body-plans evolved remains one of the most exciting and challenging goals for evolutionary and developmental biologists alike. Evolution shapes phenotypes (including morphology and behavior) by ultimately tinkering with cellular characteristics. Whereas molecular genetic approaches have revealed gene networks that control morphogenesis, and have enabled comparisons of genetic pathways across deep evolutionary time scales, a full understanding of how specification networks control cell biological functions is lacking. Furthermore, the vast majority of these data were generated in just a handful of “model” organisms that are genetically tractable, such as mouse, fly, round worm, and zebrafish. Recent breakthroughs in applying modern molecular techniques to a broader range of research organisms are enabling a better understanding of cellular regulation and co-ordination during morphogenesis along under-sampled branches of the animal tree of life. In this collection, four review articles highlight advances in understanding morphogenesis at a cellular level in systems ranging from vertebrate limb regeneration, to muscle development in ascidians, to the amniote jaw, and diverse organisms adapted to extreme environments. Future work in these systems and others will reveal a more complete picture of diverse cellular characteristics, not just from a comparative perspective, but from a functional one. With a mechanistic understanding of how cells build and shape body plans, we will be able to assess which cell types and morphogenetic processes are conserved versus convergently-evolved, versus being truly evolutionarily novel.