Meeting Abstract
The repeated evolution of key features is a theme in evolution, but whether centralized nervous systems (CNSs) fit this pattern is still under debate. Within Bilateria, the three main clades (Deuterostomia, Ecdysozoa, Spiralia) all show a great diversity in CNS development. In vertebrates and insects, specification of neural ectoderm is largely a result of inhibition of BMP signaling during dorsal-ventral axis specification. This in conjunction with the discovery that BMP signaling has been involved in specification of the directive axis in at least some cnidarians—albeit not for neural specification—and thus possibly prior to the evolution of bilaterians, has led to a hypothesis that BMP signaling in axis formation, and possibly CNS formation is homologous across Bilateria. Under this hypothesis, the full diversity of CNS morphologies, such as a dorsal vs ventral nerve cord or degree of cephalization, may result from later diversification from a single primordial CNS. Sorely lacking to complete our understanding of evolution of CNSs is data from the third major group of bilaterians, Spiralia. Initial attempts to understand the role of BMP signaling in spiralians contradicts the idea of homologous CNS development, but further work is needed to thoroughly evaluate potential evolutionary scenarios surrounding the origin of bilaterian nervous systems. Here we investigated the role of BMP type 1 and 2 receptors during development of the spiralian annelid Capitella teleta to deepen our understanding of CNS formation in the third major clade of Bilateria.
