Fig. 2. The QA motif has a limited role in haltere development. Haltere genotypic series for both haltere size and number of ectopic bristles (small blue arrows, single; large blue arrow, large quantity): (A) Ubx⁺/Ubx⁺ > (B) Ubx^QA/Ubx^QA > (C) Ubx^–/Ubx⁺ > (D) Ubx^QA/Ubx^–. Ubx⁺/Ubx⁺ halteres never had bristles, whereas Ubx^QA/Ubx^– always had several bristles. In the WI129 background (shown above), Ubx^QA/Ubx^QA flies had 0.86±0.73 bristles per haltere, whereas Ubx^–/Ubx⁺ flies had 2.59±1.04 bristles per haltere (P<10^–17; n=90 and 60, respectively). In the Oregon-R background (not shown), Ubx^QA/Ubx^QA flies had 0.14±0.25 bristles per haltere, whereas Ubx^–/Ubx⁺ flies had 0.78±0.50 bristles per haltere (P<10^–17; n=90 and 60, respectively). Anterior is leftwards, dorsal is upwards.