Drosophila melanogaster Zelda and Single-minded collaborate to regulate an evolutionarily dynamic CNS midline cell enhancer

► Drosophila Zelda controls link (CG13333) CNS midline and tracheal expression. ► Zelda collaborates with Single-minded and Trachealess. ► link midline expression recently evolved. ► Changes in enhancer sequence underlie evolutionary differences in link expression. ► Alternative splicing generates a Zelda protein with potentially altered DNA-binding properties.