Figure 6. Anterior structures “calculate” their distances from each other during the normalization process.

A) Landmarks for the left and right jaws, and the left and right nostrils were located in images collected from all three groups at d9, d23, d30, d51-d90, d91-d130 and d131-d167. This image shows the location of jaws (X) and nostrils (O) in unaffected and perturbed tadpoles at the earliest and latest ages examined. B) Tocalculate the relative differences in location of each landmark along the anterior-posterior and left-right axes, the coordinates describing the position of each landmark at day 167 were subtracted from the coordinates describing the location of the same landmark at d9. Shown here are two examples of the relative differences in location of the left jaw and left nostril in unaffected tadpoles. Clearly, between d9 and d167, the left nostril moves further in the anterior and right directions compared to the jaw on the same side. C) Quantification of movements in the anterior-posterior and left-right axes for left and right jaws and nostrils. In unaffected tadpoles (green), the majority of movements between d9 and d131-167 were in the anterior direction with little movement along the left-right axis. Animals with perturbations on the left side (red) had extensive anterior movements of the left jaw that were more than twice the distance moved in unaffected tadpoles, and decreased movements in the anterior direction for structures on the right side (jaw and nostril). Animals with perturbations on the right side (blue) had heightened movements of the right jaw that were largely in the anterior direction. Sample sizes for all analyses: unaffected n=10, perturbed left side n=10, perturbed right side n=9.