Modulation of Wnt signaling: A route to speciation?

The Phylum Cnidaria diverged from the line leading to the Bilateria approximately 630 million years ago, making them well positioned to provide insights into the diversification of eumetazoan body plans and the molecular mechanisms by which body patterning is controlled.1,2 Our recent paper3 focused on Wnt-mediated axis formation during both metamorphosis and regeneration in the cnidarian Hydractinia echinata. We showed functionally that Wnt promotes oral and inhibits aboral development, as well as repressing the formation of additional Wnt-mediated oral organisers. It is possible to relate the role of Wnt in axial patterning to the broader question of how such a wide variety of body plans evolved from the eumetazoan ancestor, given the remarkably conserved genetic toolkit among metazoans. Our results demonstrate how even a slight initial change in a single gene's expression (temporal or spatial) could provide a radical body plan alteration on which natural selection may act and could eventually lead to the establishment of a new species.