zen and the art of phenotypic maintenance: Canalization of embryonic dorsal-ventral patterning in Drosophila

We recently uncovered a novelgenetic mechanism that generates the phenotypic uniformity, or canaliza-tion, of BMP signaling and cell fate spec-ification during patterning of the dorsal-ventral (D/V) axis in D. melanogaster embryos. We went on to show that other wild-type Drosophila species lack this canalizing genetic circuitry and, conse-quently, have non-robust D/V pattern-ing. In this review, we propose molecular mechanisms that may give rise to stereo-typed BMP signaling, and we identify an additional species that could have decan-alized D/V patterning. Extension of these analyses could in turn help explain wh