Diversity of molecules and mechanisms in establishing insect anterior–posterior polarity

• AP axis determination is surprisingly variable in evolution.
• Significant divergence in early embryo patterning can occur even within a single species.
• Unbiased screens at different taxonomic levels required to move field forward.

Anterior–posterior (AP) patterning is an essential process that requires the generation of large amounts of positional information to properly specify many distinct cell fates along the long axis of the insect embryo. While the general molecular basis of this process has long been known in the fly Drosophila, detailed understanding of this process is still emerging in other insect species. What is now clear is that this process in extremely labile, and distinct AP patterning programs can exist even within a single species. This review presents recent progress on this topic in an attempt to synthesize the disparate data and provide an outlook on the future of the field.