Frizzled1 and Frizzled2 are not redundant for competitive survival under low-Wingless levels in the developing <em>Drosophila</em> wing epithelium

In the Drosophila wing epithelium, canonical Wnt signalling is activated by the gradient of secreted Wingless protein (Wnt1 homolog), which interacts redundantly with the Frizzled1 and Frizzled2 receptors. While sharing overlapping functions, these receptors also have distinct non-canonical roles and exhibit differential expression patterns along the Wingless gradient. Moreover, Frizzled2, unlike Frizzled1, is thought to be essential for sustaining low-level Wingless signalling and promoting...